Research ArticleStudies on Characterization of Corn Cob for Application ina Gasification Process for Energy Production

Anthony I Anukam12 Boniswa P Goso1

Omobola O Okoh1 and Sampson N Mamphweli2

1Department of Chemistry University of Fort Hare Private Bag X1314 Alice 5700 South Africa2Fort Hare Institute of Technology University of Fort Hare Private Bag X1314 Alice 5700 South Africa

Correspondence should be addressed to Anthony I Anukam aanukamufhacza

Received 7 February 2017 Revised 29 April 2017 Accepted 8 May 2017 Published 11 June 2017

Academic Editor Kaustubha Mohanty

Copyright copy 2017 Anthony I Anukam et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Quintessential characteristics of corn cobwere investigated in this study in order to determine its gasification potential Results wereinterpreted in relation to gasification with reference to existing data from the literature The results showed that the gasification ofcorn cobmay experience some challenges related to ash fouling slagging and sintering effects that may be orchestrated by high ashcontent recorded for corn cob which may contribute to increasing concentration of inorganic elements under high temperaturegasification conditions even though EDX analysis showed reduced concentration of these elements The study also found thatthe weight percentages of other properties such as moisture volatile matter and fixed carbon contents of corn cob as well as itsthree major elemental components (C H and O) including its clearly exhibited fiber cells make corn cob a suitable feedstockfor gasification FTIR analysis revealed the existence of ndashOH CndashO CndashH and C=C as the major functional group of atoms inthe structure of corn cob that may facilitate formation of condensable and noncondensable liquid and gaseous products duringgasification TGA results indicated that complete thermal decomposition of corn cob occurs at temperatures close to 1000∘C at aheating rate of 20∘Cmin

1 Introduction

The quest for energy is expanding rapidly all around theworld resulting in increasing pressure on power generatingsystems in most countries especially in developing countriessuch as South AfricaThese have necessitated the use of alter-native means of power generation that will not only ease thepressure on power generating systems but also have reducedconsequential impact on the environment Renewable sourceof energy is the most convenient alternative energy sourceto dwindling power generating capabilities imposed by risingenergy demand

South Africa is one of many developing countries inthe world with quite a number of rural settlements that areassociated with energy challenges because of the difficultiesin extending the national electricity grid to these settlementsTherefore the energy needs of these remote areas have to bemet by off-grid technologies that are economically viable and

sustainableThere are basically four different types of off-gridpower generation methods namely solar wind and hydro-as well as dendro (biomass)-power generation Because of thehigh cost associated with the first three power generationfrom biomass happens to be the most convenient and yetefficient method of providing energy to remote settlementshowever the importance of the type and availability of thebiomass to be used as feedstock in the energy conversionprocesses cannot be overemphasized [1]

Corn cob (CC) is a biomass feedstock with direct poten-tial as an energy resource that can be used in gasificationsystems for energy production It has a number of advantagesover other biomass feedstocks including its dense and uni-form nature as well as its increased energy content and its lowsulfur and nitrogen concentrations [2] It is an agriculturalresidue that is generated from maize and remains part of theear on which the kernels grow In most established countriesCC is usually disposed and destroyed by fire on the farms

HindawiJournal of ChemistryVolume 2017 Article ID 6478389 9 pageshttpsdoiorg10115520176478389

2 Journal of Chemistry

to prepare for the next coming season The dumping andburning of CC on the farms constitute gross air pollution InSouth Africa corn is a very important food for many peopleand it remains themost critical horticultural harvest formorethan 70 million homestead families around the world [3 4]

CC residues are sufficiently available in South Africa andare produced in large quantities by the maize industry whichhappens to be one of the largest producers of agriculturalresidues in the country as approximately 11 million tons ofCC is produced per year [5] The conversion of CC into anenergy carrier gas known as syngas through gasification is aviable alternative to electricity generation needed to meet theever escalating energy demands of remote settlements [6 7]Before this can be achieved there is a need to investigate thecharacteristics of CC that are relevant to gasification in orderto accurately predict its performance during gasification sincethe operation of energy conversion systems has been quitecompromised because of the wide variety of biomass originthat affects its composition and characteristics

Ethanol production from lignocellulosic biomass is facingquite a number of challenges Among these issues are gettingrid of the lignin content of the biomass (delignification) aswell as conversion of its cellulose and hemicellulose con-tents into fermentable sugars through fermentation [8] Theprocess of finding a way around these challenges is stillunder investigation However with gasification any biomassmaterial can be successfully converted into useable energywithout the need for delignification The syngas producedfrom gasification can be further processed into other chemi-cals via different reforming processes It can also be convertedinto fuels through the Fischer Tropsch process Anotheradvantage of gasification as compared to other bioenergygeneration technologies is its ability to utilize a wide varietyof biomass feedstocks ranging from any agricultural or plantresidue industry organic by-products or even municipalwastes and hence gasification is considered a viable tech-nique for producing energy from biomass feedstocks whichcannot be technically or economically fermented to ethanol

Gasification occurs under a sequence of successive reac-tions that are mostly endothermic in nature The followingreactions take place during biomass gasification [9 10]

Oxidation reaction is

C +O2997888rarr CO

2(+393MJkgmole) (1)

Reduction reaction is

C +H2O 997888rarr H

2+ CO (+1226MJkgmole) (2)

Water-gas shift reaction is

CO +H2Olarrrarr CO

2+H2(minus412MJkgmole) (3)

Methanation reaction is

C + 2H2larrrarr CH

4(+75MJkgmole) (4)

Reaction (1) typically occurs in the combustion zone ofthe gasifier with a theoretical temperature of over 1200∘C

hence oxidation reactions of a gasification process are alsoreferred to as combustion zone reactionsThe second reaction(reaction (2)) represents the medium where the product ofpartial oxidation (ie products that were not fully combustedin reaction (1)) passes through which is the reaction repre-senting the red-hot bed of charcoal that is capable of reducinggas temperature because of the reactionrsquos endothermic naturewhile reaction (3) depicts the prominent water-gas shiftreaction that is themajor determinant of the yield and qualityof the syngas produced froma gasification processThe fourthreaction (reaction (4)) is the hydrogasification reaction thatis also known as the methanation reaction which forms veryminute levels of methane during gasification [9]

Gasifiers operate satisfactorily only within certain rangesof feedstock characteristics as such knowledge of the char-acteristics of the feedstock to be used during gasification isrequired in order to predict its performance prior to gasifi-cation [11] Analytical instruments such as CHNS analyzeratomic absorption spectrometer (AAS) thermogravimetricanalyzer (TGA) and scanning electron microscopic (SEM)analyzer are very useful instruments to determine the charac-teristics of biomass materials for the purpose of gasificationPrevious studies from other researchers have used theseinstruments to determine the sintering characteristics andmineral transformation behaviour of corn cob ash (CCA)[7] Kumar et al 2008 [12] used TGA to study the thermalcharacteristics of corn stover (CS) as a gasification andpyrolysis feedstock while Arun and Ramanan 2016 [13]conducted experimental studies on the gasification of CC ina fixed-bed system after determining the characteristics ofCC using a muffle furnace an ultimate analyzer and a bombcalorimeter to provide information on physical and chemicalproperties of the material as well as its energy contentrespectively In another study Aboyade et al 2013 [14]determined the nonisothermal thermokinetics of copyrolysisof a blend of two different biomass materials that includedcorn residue with coal In addition to the physical chemicaland thermal properties of CC there is a lack of specificinformation on its characterization intended to reveal itssurface and internal structural properties for the purposeof gasification The objective of this study therefore is toestablish the characteristics of CC relevant to gasification in adowndraft system and to interpret the information obtainedfrom these characteristics in relation to gasification based onexisting data from the literature

The characteristics of CC in terms of proximate andultimate analysis as well as in terms of energy value (heatingvalue) reported by previous researchers for various applica-tions different from gasification are presented in Tables 1 and2 respectively

The difference in the reported values in both Tables 1and 2 may be essentially due to a combination of factorsthat includes the source of the CC its handling storage andclimatic conditions as well as soil type and texture where thecorn was grown including the tendency of the corn plantto uptake nutrients from the soil The ash content variedprobably because of different methods of harvesting and theamount of nutrients (fertilizers) applied to the corn plantduring growth It is valuable from another overview that

Journal of Chemistry 3

Table 1 Proximate analysis of corn cob from previous studies(wt)

Author MC VM AC FC[15] 46 799 18 137[16] 1174 7233 1067 497[17] mdash 787 09 162

Table 2 Ultimate analysis of corn cob from previous studies (wt)

Author C H N S O HHV (MJkg)[15] 502 59 042 003 435 1914[16] 462 542 092 024 4722 1836[17] 455 62 13 mdash 470 mdash

the inorganic compounds contained in CC with higher ashcontent have potential to be used as catalyst in thermalconversion systems [16]

2 Experimental

21 Sample Preparation The corn cob (CC) used for thisstudy was obtained from a local farm in Alice in the EasternCape Province of South Africa It was dried outdoors atan average temperature of about 30∘C to lower its moisturecontentThis was followed bymilling to a size required by theinstruments that were used for analysesThe dried andmilledCC was preserved in a desiccator prior to analyses

22 Proximate Analysis Information required for moisturevolatile matter and ash as well as fixed carbon contents of CCwas given by proximate analysisThese properties are relevantto the thermal conversion of any biomassmaterial into energy[19]Theproximate analysis data of CCwas obtained from theTGA plot presented in Figure 2 following a modified ASTMD 5142-04 standard test method [18 20] They were obtainedaccording to the equations in Table 3

Moisture content was determined by weight loss attemperatures close to 100∘C while volatile matter contentrepresented the mass evolved between the temperatures of100 and 550∘C After heating of the sample to about 1000∘Cduring TGA the remaining mass was considered as beingash and the fixed carbon content of CC was obtained bydifference

23 Ultimate Analysis This analysis provided information onthe elemental components of CC both in qualitative and inquantitative terms A Thermo Quest CHNS elemental ana-lyzer was used for this purposeThe proportion of carbon (C)hydrogen (H) sulfur (S) and nitrogen (N) were determinedwhile oxygen (O) was obtained by difference

About 5mg of milled CC was placed in a tin capsulethat contained an oxidizer prior to combustion in a reactionat 1000∘C This led to a violent reaction as the sample andtin capsule decomposed creating a condition where all heatresistant substances became fully oxidized The productsobtained were made to pass through a high purity copper at

Table 3 Equation parameters used for proximate analysis determi-nation from TGA curve [18]

Equationname Parameters

Moisturecontent (([Initial Mass] minus [Moisture Mass])

[Initial Mass] ) times 100

Volatilemattercontent

(([Moisture Mass] minus [Volatile Mass])[Initial Mass] ) times 100

Ash ( [Ash Mass][Initial Mass]) times 100

Fixedcarbon 100 minus ([Moisture] + [Volatile] + [Ash])

500∘C in order to rid the process of any oxygen that was notcompletely consumed during the combustion process Thereis always a need to employ high purity substances duringCHNS analyses for the purpose of oxidation and to removeunwanted materials that may interfere with analyses results[21] Complete oxidation was ensured by using tungstentrioxide and copper downstream of the combustion chamberof the instrument Combustion products such as carbondioxide (CO

2) sulfur dioxide (SO

2) and nitrogen dioxide

(NO2) were obtained after the analysis which were all

separated by gas chromatography and the elementsmeasuredwith a thermal conductivity detector

The energy value also known as heating value andreported in terms of higher heating value (HHV) of CCwas calculated from the mass fractions of the elementalcomponents obtained from CHNS analysis which was doneaccording to [22]

HV (MJkg) = minus13675 + 03137 times C + 07009 timesH+ 00318 timesO (5)

where HV is the heating value measured in MJKg while CH and O are the carbon hydrogen and oxygen contents ofCC

24 FTIR Analysis The Fourier Transform Infrared (FTIR)spectroscopy also deals with quantitative and qualitativeanalysis of organic samples and recognizes chemical bondsin a molecule by generating an infrared retention rangethe spectra generate a profile of the sample a particularmolecular fingerprint that can be utilized to screen andscan samples for a wide range of segments [23] FTIR is anoperative analytical instrument for distinguishing functionalgroups and characterizing covalent bonding data In thisstudy it was used to determine themost reactive componentsof CC in terms of functional groups since the rate ofgasification reactions depend on the chemically active groupof components of the biomass used as feedstock [24]

About 05mg of the sample was mixed with 025ndash050of KBr and placed in the FTIR test holder The sample

4 Journal of Chemistry

was examined by a fully computerized Perkin Elmer FTIRsystem which produces the absorbance spectra that demon-strate the unique chemical bonds and the atomic structureof the sample material This profile was in the form ofan absorption spectrum that indicated peaks representingcomponents in higher concentration Absorbance peaks onthe spectrum also indicated the functional groups Differenttypes of bonds and thus different functional groups absorbedinfrared radiation of various wavelengths Despite the factthat the analysis was performed in absorbance mode it canbe converted into a transmittance mode since they are justthe reverse of each other The analytical spectrum is thencontrasted in a reference library program with catalogedspectra to identify components for unknown material usingthe cataloged spectra for known materials

25 Thermogravimetric Analysis (TGA) The thermal behav-iour of biomass materials are usually measured by a thermo-gravimetric analyzer (TGA) which measures the percentageweight loss of the biomass as a function of temperature andthe resulting thermogram has a peculiar shape for biomassmaterials [25] In addition to studying the thermal behaviourof CC this analysis was undertaken in order to establish thethermal parameters that would impact on the gasification ofthe material It is worth noting that most TGA experimentsare conducted under a chemically inactive environment (ofwhich nitrogen or argon is often used) to show the effectof heat degradation that includes carbonization oxygen ishighly reactive and usually not recommended during analy-ses involving TGA because it reacts with sample componentsleading to loss of original sample in the process [24]

A 781mg of the sample was combusted in a SDT Q600TGA instrument under a nitrogen atmosphere at a flow rateof 35mLmin between 35 and 1000∘C Nitrogen was used tocreate a chemically inactive environment so as to preventthe TGA instrument from overheating A heating rate of20∘Cmin was used during TGA because this is characteristicof gasification systems using the downdraft gasifier [11]

26 SEMAnalysis Scanning ElectronMicroscopy (SEM) is ahigh resolution imaging system with an extraordinary depthof field It indicates topographical structural and elementaldata at lowmagnifications up to 200000x [26]Theutilizationof SEM innovation is a priceless guide in distinguishingand portraying mineral and material stages together withsurface components SEM in this study was used for surfacemorphological view of the material to establish if CC isenough carbonaceous material that would be suitable forgasification using the downdraft gasification system

The SEM analysis of CC was undertaken by a JEOL(JSM-6390) operating with accelerating voltage of 15 kVThe micrographs were generated at different magnifications(250ndash1000x) by a computer program The data was collectedover a selected area of the surface of the sample and atwo-dimensional image was generated that displayed spatialvariations in properties

Table 4 Measured physical characteristics of corn cob

Proximate analysis (wt)Moisture content 51Volatile matter content 651Ash content 85Fixed carbon 213

3 Results and Discussion

In this section the findings of this study are presenteddiscussed and substantiated with reference to existing datafrom the literature

31 Physical Characteristics of Corn Cob Gasifiers amongother factors operate satisfactorily with regard to efficiencyonly within certain ranges of feedstock characteristics [11]Table 4 shows the data obtained from the physical character-ization of CC which were obtained from the thermogravi-metric plot of the sample presented in Figure 2 employingthe equations presented in Table 3

From Table 4 moisture content of CC was measured as51 which is quite different when compared to the valuesreported in the literature It is lower than the value of 1174reported by Danish et al 2015 [16] and higher than thevalue of 46 reported by Danje 2011 [15] in Table 1 Thedifference in these values may be attributed to a numberof reasons including the source of the CC and handlingconditions However this value (51) for moisture content isdesirable for gasification to take place as materials with mois-ture content beyond 20 would create technical difficultieslinked to poor combustion conditions within the gasificationsystem andwill inhibit immediate combustion of thematerialat the same time increasing its smoking propensity witha consequent reduction in gasification process efficiency[24] It can also be noted that the CC used for this studyis characterized by relatively high volatile matter content(651) which was anticipated because of the organic natureof the material The contents of volatile matter in biomassmaterials are usually high due to the organic nature of thebiomass which indicates the biomass potential to create hugeamounts of inorganic vapours when used as feedstock in agasification process the higher the volatile matter contentof biomass the better its combustion and gasification ratesbecause of the biomass yield upon carbonization [25] Thematerial is also characterized by high ash content that mayalso be attributed to a number of factors that include thosepreviously given in Section 1 This high content of ash maynot be favourable to gasification because of issues linkedto sintering and slagging that may be experienced duringgasification which might also contribute to reduction inprocess efficiency Biomass ash content greater than 6 isnot desirable for gasification because it creates technicalissues related to agglomeration fouling and sintering as wellas slagging that may together reduce gasification efficiencyhowever ash may exert some catalytic effect that may allowfor cracking of higher molecular weight compounds such as

Journal of Chemistry 5

Table 5 Measured elemental components of corn cob

Ultimate analysis (wt)C 444H 56N 043S 13O (by difference) 4827

tar into lighter ones for optimum gasification efficiency [27ndash29] The fixed carbon content of CC was also found to beabout 21 which is high enough to allude that there will beincreased formation of char during gasification as the relativeproportions of the content of volatile matter and fixed carbonare related to the yields and composition of solid liquid andgaseous products formed during gasification [30]

32 Chemical Characteristics of Corn Cob The ratio of theproducts formed during gasification of biomass is influencednot just by its physical characteristics but also by the chemicalcomposition of the biomass fuel and the operating conditionsof the gasifier [31]The chemical properties of CCwas studiedin order to obtain information regarding the relative pro-portions of the major elemental components of the materialand to predict the impact of these components on syngasquality and yield as well as on the environmental effects ofgasifying CC Table 5 shows the elemental components of CCas measured by the CHNS analyzer

The data in Table 5 shows that CC is composed of threemajor elements with a higher proportion of oxygen thancarbon The higher oxygen proportion is the reason for thelow energy value reported forCC in Section 35However thishigher oxygen content implies increased thermal reactivityduring gasification Increased biomass oxygen content is anindication of increased thermal reactivity of biomass duringthermochemical conversion processes the gasification ofbiomass is centered on carbon conversion [11]The content ofhydrogen is in agreement with most findings in the literatureand had positive contribution to the energy value of CCreported in Section 35 together with its content of carbonOxidation of carbon and hydrogen contents of biomass areusually initiated by exothermic reactions during gasificationforming CO

2and H

2O with the CO

2emitted as a product

of complete combustion [24]The relatively low nitrogen andsulfur contents imply lower amounts of NH

3 HCN and H

2S

(which are environmentally harmful compounds) may beanticipated during gasification

33 Metallic Elemental Components of Corn Cob In additionto nonmetallic elemental components of biomass there arealso metallic elemental components such as Na K Mg andSi that are especially responsible for the concentration of ashin biomass materials in other words the weight percentageof these metallic elements to an extent determines theoverall weight percentage of ash contained in biomass as highconcentration of these elements creates technical hitches suchas fouling sintering and slagging because of volatilization of

Table 6 Weight percentages of the metallic elemental componentsof corn cob

Element Composition (wt)Al 031K 153Si 044Na 132Ca 011Mg 042Fe 006

the elements which forms liquid slags on cooling when thebiomass is used as feedstock in gasification processes [32]Table 6 shows the weight percentages of themetallic elementscontained in CC which were obtained after analysis usinga Thermo Scientific Model ICE 3500 Atomic AbsorptionSpectrometer (AAS) equipped with hollow cathode lamps

It is quite obvious that the concentrations of the metallicelements are relatively low implying that there may be littleor no technical issues related to those previously mentionedwhen CC is used as feedstock in a gasification process Thereasons for the low concentration of these elements are thesame as those given for the high content of ash reported inTable 4 These ash-forming elements are usually taken up byplants during growth the elemental composition of biomassespecially with regard to the weight percentages of the ash-forming elements has key impact on ash transformationsequences and sintering behaviours [7 24] Ash-formingelements are usually characterized by complex transforma-tion reactions during biomass gasification creating technicalissues linked to those previously mentioned however reac-tions involving the oxides of calcium or magnesium withpotassium silicates lead to formation of high-temperature-melting calcium-magnesium-potassium silicates that playsignificant roles in the reduction of sintering issues duringgasification because of the limit in the formation of silicatesthat are rich in potassium [7 24 33 34] For fixed-bedgasification systems such as the downdraft system ash-related sintering proceeds with the formation of slag as aconsequence of certain factors like bridging coalescence andaccumulation of the sintered ash residues on gasifier gratesThe slag with large sizes cannot be transported out from thegrate which then interferes with the gasification process andreduces the performance of gasification appliances [35ndash37]

34 Reactive Components of Corn Cob To gain a deeperunderstanding of the chemistry of CC and to provide abaseline for the prediction of its gasification performance adiagnosis of the internal structure of thematerial is necessaryThis diagnosis relates to analysis of the materialrsquos reactivecomponents in terms of the functional groups present inits structure The spectrum associated with the structureof CC and the indicated peaks relative to each functionalgroup are presented in Figure 1 The absorbance at variouswavenumbers corresponds to the functional groups

6 Journal of Chemistry

102

101

100

99

98

97

96

95

94

Tran

smitt

ance

()

5000 4000 3000 2000 1000 0

Wavenumber (cmminus1)

Figure 1 FTIR spectrum of corn cob

0

20

40

60

80

100

0 200 400 600 800 1000

Wei

ght L

oss (

)

Temperature (∘C)

Figure 2 Thermogram resulting from the thermal analysis of corncob

It is quite obvious from Figure 1 that the peak at3303 cmminus1 corresponds to OndashH stretching vibrations thatindicates the presence of hydroxyl groups while that near2844 cmminus1 depicts CndashH stretching that corresponds to thepresence of alkanes 1000 cmminus1 depicts CndashO stretching withthe peak near 600 cmminus1 showing characteristics of CndashHbending These functional groups represent the chemicallyactive components of biomass that accelerates the rates of thegasification reactions presented in Section 1 [24]

Nonetheless for better understanding of the functionalgroups common to the structure of CC Table 7 presents thechemically active components related to the bonds of theatoms that make up the material and which take part duringthermal conversion processes

During gasification the presence of the ndashOH group willinitiate and accelerate the rate of condensation reactionscreated by dehydroxylation as a result of thermal decom-position of the cellulose content of the material caused byrising temperatures within the gasifier while CndashH presencedue to alkanes is connected to the reactions leading tohemicellulose degradation [24] The existence of the C=Cgroup which is an indication of the presence of alkenesfacilitates reactions leading to lignin decomposition whilethe group CndashO which is assigned to carboxylic groups in

Table 7 Functional groups present in the structure of corn cob

Frequencyrange(cmminus1)

Groups Class of compounds

3303 OndashH stretching Alcohol phenols2844 CndashH stretching Alkanes1589 C=C bending Aromatic compounds1029 CndashO stretching Alcohol phenols amp esters582 CndashH bending Aromatic compounds

cellulose and hemicellulose speeds up the rate of otherreactions such as decarboxylation reactions that leads to thebreakage of glycosidic bonds that consequently forms a seriesof less oxygen-containing compounds such as ethers acidsand aldehydes and noncondensable gases such as CO andCO2[24 38]

Plant photosynthesis is usually driven by energy from thesun that is usually stored in chemical bonds of the structuralcomponents of the plant implying that an amount of energywould be required to break these bonds in order to harnessthe energy which is mostly achieved through initiation ofgasification reactions when the plant material is to be usedas feedstock in a gasification process [11 28]

35 Energy Value of Corn Cob Plants convert energy fromthe sun into chemical energy that is stored in the structuralcomponents of the biomass by using CO

2in the atmosphere

[24] The energy value of CC was determined to evaluate theamount of energy available for conversion which is a veryimportant property of biomass because conversion efficiencyof a gasification process depends on it [11] In this study theenergy value of CC was measured as 1802MJkg a valuethat is in agreement with those reported by Danje 2011 andDanish et al 2015 [15 16] in Table 2 It is therefore sufficientto allude that the energy value of CC measured in this studyis in agreement with most findings in the literature

36Thermal Behaviour of CornCob In order to better under-stand the gasification characteristics of CC thermal analysisof the sample using an instrument relevant to gasification isnecessary This analysis is intended to establish the thermalbehaviour of the sample under both high and low tempera-tures as well as determine the thermal parameters that wouldinfluence its gasification Figure 2 shows the thermogramobtained from the thermogravimetric analysis of CC

The plot in Figure 2 shows that as temperature increasesthere is a marked reduction in the weight of the sample Theplot also shows that the thermal degradation behaviour of CCis characterized by three different weight loss stages with theinitial one at 94∘C which signifies the removal of moisturefrom the sample A significant weight loss could be observedbetween 200 and 500∘C and represents the second stage of thedecomposition process of the sample This may be attributedto the decomposition of basic organic components ofCC suchas cellulose hemicellulose and lignin the decomposition of

Journal of Chemistry 7

(a) (b)

(c) (d)

Figure 3 SEM images of corn cob obtained at different magnifications

these components releases volatile gases such as CO2and

CH4that are mainly formed due to the decomposition of

hemicellulose between the temperatures of 190 and 320∘CThis degradation temperature for hemicellulose implies lessproduction of tar and char during gasification of CC [24]The third stage of the thermal decomposition process ofCC is indicated by cellulose and lignin degradation between280 and 400∘C for cellulose and between 320 and 450∘C forlignin with total combustion of the sample taking place as itsweight is reduced in the process to give rise to decompositionof hydrocarbons During gasification cellulose and lignindegradation at higher temperatures depict the production ofcarbonized biomass as well as heavy organic and inorganiccompounds [39 40]

37 Microstructural Characteristics of Corn Cob The surfacestructure of CC was examined with a scanning electronmicroscopic instrument that offered detailed informationon imaging and surface composition of the sample Thisprovided a guide as to whether CC is enough carbonaceousmaterial suitable for gasification in a downdraft gasifierFigure 3 shows the SEM images of CC obtained at differ-ent magnifications The images were magnified by a factorof 250 for better understanding and interpretation of themicrostructural characteristics of the material

As can be seen from the images in Figures 3(a)ndash3(d) theshapes are quite irregular and agglomerated The sample is

clearly seen to have no pores even at higher magnificationsan evidence of lack of pretreatment prior to analysis butit exhibits cells on the surface without much characterizedstructure However at 250 magnification (Figure 3(a)) thereseem to be plenty of parallel lines that appear on the surface ofthe sample which look like cells of residual pith that providesa pathway for the transportation of water and nutrients fromthe soil but on increasing magnification to 500 (Figure 3(b))these lines seem to disappear showingmore vascular bundleswith not too conspicuous fragmented cells which indicatesfibrous lignocellulosic nature of CC which is a commonfeature of agricultural biomass residues [24] At higher mag-nification (times750 Figure 3(c)) the vascular bundles are morepronounced with the fragmented cell structures more visibleThepresence of the vascular bundles and cell structures are anindication of carbon-oriented structures which corroboratesthe carbon content data of CC presented in Table 5These cellstructures are also associated with the formation of pathwaysfor the production of gaseous products these features makeCC amenable to high temperature gasification that connotesoptimum efficiency [24 39 41] As image magnification wasincreased to a maximum of 1000 (Figure 3(d)) more featureswere revealed including the size of the vascular bundles andtheir compact nature which are important features used tounderstand the combustion behaviour of biomass materials[42]

8 Journal of Chemistry

4 Conclusions

In order to evaluate CC with regard to its gasification-relatedcharacteristics a detailed assessment based on fuel analysiswas performed The experiments conducted and the resultspresented showed that CC is a biomass feedstock suitablefor gasification due to its low moisture content and due toits low concentration of metallic elements However its highpercentage of ash may create a bit of technical challengesthat may lower gasification efficiency Its low concentrationof nitrogen and sulfur implies reduced emissions of NOXand SO

2during gasification and its hydrogen concentration

is high enough to initiate the water-gas shift reaction thatis the dominant chemical reaction which forms the majorportion of the syngas The energy value analysis showedthat CC contains a manageable amount of energy that canbe converted into useful energy through gasification Thereactive components of CC were mostly oxygen-containingfunctional groups that may play important roles duringgasification The study also established that the thermaldecomposition of CC began at temperatures below 100∘Cwith its complete degradation occurring at temperaturesclose to 1000∘C releasing enormous amount of gases whileSEM analysis revealed compacted vascular bundles and fibertissues linked to carbon-orientation that are among thefeatures of CC that may favour high temperature gasification

The results obtained form a significant basis for thedevelopment of a gasification system that would be tailoredto the demands of the characteristics of CC

Even though the CC used for this study exhibited lowconcentration of metallic elements an elevated weight per-centage of these elements is anticipated when the material isused as feedstock in a gasification process This is becauseof the high amount of ash recorded for CC The weightpercentage of the metallic elements of biomass increases withrising gasification temperature [24] As such further researchis required on reduction of the weight percentage of CCash content This study did not involve the gasification ofCC either via simulation or via experimental investigationof its gasification process This is where challenges could beexperienced with the use of CC It is therefore recommendedthat research be undertaken on the gasification of CC in orderto adequately establish the impact of fuel characteristics ongasification process efficiency The reaction kinetics of thethermal decomposition of CC also require further studies

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

The authors wish to acknowledge the financial support of theNational Research Foundation of South Africa (NRF) theGovanMbeki Research andDevelopment Center (GMRDC)and the Chemistry Department of both the University of FortHare and the Fort Hare Institute of Technology (FHIT) fortheir technical assistance

References

[1] D Gunarathne Optimization of the performance of downdraftbiomass gasifier installed at national engineering research anddevelopment (NERD) Centre of Sri Lanka [Msc thesis] KTHSchool of Industrial Engineering and Management Sweden2012

[2] Extension Farm Energy ldquoCorn cobs for biofuel productionrdquohttparticlesextensionorgpages26619corn-cobs-for-biofuel-production 2016

[3] J T Oladeji and C C Enweremadu ldquoA predictive model for thedetermination of some densification characteristics of corncobbriquettesrdquo inMaterials and Processes for Energy Communicat-ing Current Research and Technological Developments pp 169ndash177 2013

[4] Y Zhang A E Ghaly and B Li ldquoPhysical properties of cornresiduesrdquo American Journal of Biochemistry and Biotechnologyvol 8 no 2 pp 44ndash53 2012

[5] SA Department of Agriculture ldquoMaize productionrdquo httpndaagriczapublications 2016

[6] M Y Suberu A SMokhtar andN Bashir ldquoPotential capabilityof corn cob residue for small power generation in rural NigeriardquoARPN Journal of Engineering and Applied Sciences vol 7 no 8pp 1037ndash1046 2012

[7] L Wang J E Hustad and M Groslashnli ldquoSintering characteristicsand mineral transformation behaviors of corn cob ashesrdquoEnergy and Fuels vol 26 no 9 pp 5905ndash5916 2012

[8] J Lee ldquoBiological conversion of lignocellulosic biomass toethanolrdquo Journal of Biotechnology vol 56 no 1 pp 1ndash24 1997

[9] R N Andre F Pinto C Franco et al ldquoFluidised bed co-gasification of coal and olive oil industry wastesrdquo Fuel vol 84no 12-13 pp 1635ndash1644 2005

[10] J Fermoso Pressure co-gasification of coal and biomass for theproduction of hydrogen University of Oviedo Spain 2009

[11] A Anukam S Mamphweli E Meyer and O Okoh ldquoComputersimulation of the mass and energy balance during gasificationof sugarcane bagasserdquo Journal of Energy vol 2014 Article ID713054 9 pages 2014

[12] A Kumar L Wang Y A Dzenis D D Jones and M AHanna ldquoThermogravimetric characterization of corn stover asgasification and pyrolysis feedstockrdquo Biomass and Bioenergyvol 32 no 5 pp 460ndash467 2008

[13] K Arun and M V Ramanan ldquoExperimental studies on gasifi-cation of corn cob in a fixed bed systemrdquo Journal of Chemicaland Pharmaceutical Research vol 8 pp 667ndash676 2016

[14] A O Aboyade J F Gorgens M Carrier E L Meyer and JH Knoetze ldquoThermogravimetric study of the pyrolysis char-acteristics and kinetics of coal blends with corn and sugarcaneresiduesrdquo Fuel Processing Technology vol 106 pp 310ndash320 2013

[15] S Danje Fast pyrolysis of corn residues for energy production[dissertation thesis] Stellenbosch University 2011

[16] M Danish M Naqvi U Farooq and S Naqvi ldquoCharacteriza-tion of SouthAsian agricultural residues for potential utilisationin future energy mixrdquo Energy Procedia vol 75 pp 2974ndash29802015

[17] J Wannapeera N Worasuwannarak and S PipatmanomoildquoProduct yields and characteristics of rice husk rice straw andcorncob during fast pyrolysis in a drop-tubefixed-bed reactorrdquoSongklanakarin Journal of Science and Technology vol 30 no 3pp 393ndash404 2008

Journal of Chemistry 3

Table 1 Proximate analysis of corn cob from previous studies(wt)

Author MC VM AC FC[15] 46 799 18 137[16] 1174 7233 1067 497[17] mdash 787 09 162

Table 2 Ultimate analysis of corn cob from previous studies (wt)

Author C H N S O HHV (MJkg)[15] 502 59 042 003 435 1914[16] 462 542 092 024 4722 1836[17] 455 62 13 mdash 470 mdash

the inorganic compounds contained in CC with higher ashcontent have potential to be used as catalyst in thermalconversion systems [16]

2 Experimental

21 Sample Preparation The corn cob (CC) used for thisstudy was obtained from a local farm in Alice in the EasternCape Province of South Africa It was dried outdoors atan average temperature of about 30∘C to lower its moisturecontentThis was followed bymilling to a size required by theinstruments that were used for analysesThe dried andmilledCC was preserved in a desiccator prior to analyses

22 Proximate Analysis Information required for moisturevolatile matter and ash as well as fixed carbon contents of CCwas given by proximate analysisThese properties are relevantto the thermal conversion of any biomassmaterial into energy[19]Theproximate analysis data of CCwas obtained from theTGA plot presented in Figure 2 following a modified ASTMD 5142-04 standard test method [18 20] They were obtainedaccording to the equations in Table 3

Moisture content was determined by weight loss attemperatures close to 100∘C while volatile matter contentrepresented the mass evolved between the temperatures of100 and 550∘C After heating of the sample to about 1000∘Cduring TGA the remaining mass was considered as beingash and the fixed carbon content of CC was obtained bydifference

23 Ultimate Analysis This analysis provided information onthe elemental components of CC both in qualitative and inquantitative terms A Thermo Quest CHNS elemental ana-lyzer was used for this purposeThe proportion of carbon (C)hydrogen (H) sulfur (S) and nitrogen (N) were determinedwhile oxygen (O) was obtained by difference

About 5mg of milled CC was placed in a tin capsulethat contained an oxidizer prior to combustion in a reactionat 1000∘C This led to a violent reaction as the sample andtin capsule decomposed creating a condition where all heatresistant substances became fully oxidized The productsobtained were made to pass through a high purity copper at

Table 3 Equation parameters used for proximate analysis determi-nation from TGA curve [18]

Equationname Parameters

Moisturecontent (([Initial Mass] minus [Moisture Mass])

[Initial Mass] ) times 100

Volatilemattercontent

(([Moisture Mass] minus [Volatile Mass])[Initial Mass] ) times 100

Ash ( [Ash Mass][Initial Mass]) times 100

Fixedcarbon 100 minus ([Moisture] + [Volatile] + [Ash])

500∘C in order to rid the process of any oxygen that was notcompletely consumed during the combustion process Thereis always a need to employ high purity substances duringCHNS analyses for the purpose of oxidation and to removeunwanted materials that may interfere with analyses results[21] Complete oxidation was ensured by using tungstentrioxide and copper downstream of the combustion chamberof the instrument Combustion products such as carbondioxide (CO

2) sulfur dioxide (SO

2) and nitrogen dioxide

(NO2) were obtained after the analysis which were all

separated by gas chromatography and the elementsmeasuredwith a thermal conductivity detector

The energy value also known as heating value andreported in terms of higher heating value (HHV) of CCwas calculated from the mass fractions of the elementalcomponents obtained from CHNS analysis which was doneaccording to [22]

HV (MJkg) = minus13675 + 03137 times C + 07009 timesH+ 00318 timesO (5)

where HV is the heating value measured in MJKg while CH and O are the carbon hydrogen and oxygen contents ofCC

24 FTIR Analysis The Fourier Transform Infrared (FTIR)spectroscopy also deals with quantitative and qualitativeanalysis of organic samples and recognizes chemical bondsin a molecule by generating an infrared retention rangethe spectra generate a profile of the sample a particularmolecular fingerprint that can be utilized to screen andscan samples for a wide range of segments [23] FTIR is anoperative analytical instrument for distinguishing functionalgroups and characterizing covalent bonding data In thisstudy it was used to determine themost reactive componentsof CC in terms of functional groups since the rate ofgasification reactions depend on the chemically active groupof components of the biomass used as feedstock [24]

About 05mg of the sample was mixed with 025ndash050of KBr and placed in the FTIR test holder The sample

4 Journal of Chemistry

was examined by a fully computerized Perkin Elmer FTIRsystem which produces the absorbance spectra that demon-strate the unique chemical bonds and the atomic structureof the sample material This profile was in the form ofan absorption spectrum that indicated peaks representingcomponents in higher concentration Absorbance peaks onthe spectrum also indicated the functional groups Differenttypes of bonds and thus different functional groups absorbedinfrared radiation of various wavelengths Despite the factthat the analysis was performed in absorbance mode it canbe converted into a transmittance mode since they are justthe reverse of each other The analytical spectrum is thencontrasted in a reference library program with catalogedspectra to identify components for unknown material usingthe cataloged spectra for known materials

25 Thermogravimetric Analysis (TGA) The thermal behav-iour of biomass materials are usually measured by a thermo-gravimetric analyzer (TGA) which measures the percentageweight loss of the biomass as a function of temperature andthe resulting thermogram has a peculiar shape for biomassmaterials [25] In addition to studying the thermal behaviourof CC this analysis was undertaken in order to establish thethermal parameters that would impact on the gasification ofthe material It is worth noting that most TGA experimentsare conducted under a chemically inactive environment (ofwhich nitrogen or argon is often used) to show the effectof heat degradation that includes carbonization oxygen ishighly reactive and usually not recommended during analy-ses involving TGA because it reacts with sample componentsleading to loss of original sample in the process [24]

A 781mg of the sample was combusted in a SDT Q600TGA instrument under a nitrogen atmosphere at a flow rateof 35mLmin between 35 and 1000∘C Nitrogen was used tocreate a chemically inactive environment so as to preventthe TGA instrument from overheating A heating rate of20∘Cmin was used during TGA because this is characteristicof gasification systems using the downdraft gasifier [11]

26 SEMAnalysis Scanning ElectronMicroscopy (SEM) is ahigh resolution imaging system with an extraordinary depthof field It indicates topographical structural and elementaldata at lowmagnifications up to 200000x [26]Theutilizationof SEM innovation is a priceless guide in distinguishingand portraying mineral and material stages together withsurface components SEM in this study was used for surfacemorphological view of the material to establish if CC isenough carbonaceous material that would be suitable forgasification using the downdraft gasification system

The SEM analysis of CC was undertaken by a JEOL(JSM-6390) operating with accelerating voltage of 15 kVThe micrographs were generated at different magnifications(250ndash1000x) by a computer program The data was collectedover a selected area of the surface of the sample and atwo-dimensional image was generated that displayed spatialvariations in properties

Table 4 Measured physical characteristics of corn cob

Proximate analysis (wt)Moisture content 51Volatile matter content 651Ash content 85Fixed carbon 213

3 Results and Discussion

In this section the findings of this study are presenteddiscussed and substantiated with reference to existing datafrom the literature

31 Physical Characteristics of Corn Cob Gasifiers amongother factors operate satisfactorily with regard to efficiencyonly within certain ranges of feedstock characteristics [11]Table 4 shows the data obtained from the physical character-ization of CC which were obtained from the thermogravi-metric plot of the sample presented in Figure 2 employingthe equations presented in Table 3

From Table 4 moisture content of CC was measured as51 which is quite different when compared to the valuesreported in the literature It is lower than the value of 1174reported by Danish et al 2015 [16] and higher than thevalue of 46 reported by Danje 2011 [15] in Table 1 Thedifference in these values may be attributed to a numberof reasons including the source of the CC and handlingconditions However this value (51) for moisture content isdesirable for gasification to take place as materials with mois-ture content beyond 20 would create technical difficultieslinked to poor combustion conditions within the gasificationsystem andwill inhibit immediate combustion of thematerialat the same time increasing its smoking propensity witha consequent reduction in gasification process efficiency[24] It can also be noted that the CC used for this studyis characterized by relatively high volatile matter content(651) which was anticipated because of the organic natureof the material The contents of volatile matter in biomassmaterials are usually high due to the organic nature of thebiomass which indicates the biomass potential to create hugeamounts of inorganic vapours when used as feedstock in agasification process the higher the volatile matter contentof biomass the better its combustion and gasification ratesbecause of the biomass yield upon carbonization [25] Thematerial is also characterized by high ash content that mayalso be attributed to a number of factors that include thosepreviously given in Section 1 This high content of ash maynot be favourable to gasification because of issues linkedto sintering and slagging that may be experienced duringgasification which might also contribute to reduction inprocess efficiency Biomass ash content greater than 6 isnot desirable for gasification because it creates technicalissues related to agglomeration fouling and sintering as wellas slagging that may together reduce gasification efficiencyhowever ash may exert some catalytic effect that may allowfor cracking of higher molecular weight compounds such as

Journal of Chemistry 5

Table 5 Measured elemental components of corn cob

Ultimate analysis (wt)C 444H 56N 043S 13O (by difference) 4827

tar into lighter ones for optimum gasification efficiency [27ndash29] The fixed carbon content of CC was also found to beabout 21 which is high enough to allude that there will beincreased formation of char during gasification as the relativeproportions of the content of volatile matter and fixed carbonare related to the yields and composition of solid liquid andgaseous products formed during gasification [30]

32 Chemical Characteristics of Corn Cob The ratio of theproducts formed during gasification of biomass is influencednot just by its physical characteristics but also by the chemicalcomposition of the biomass fuel and the operating conditionsof the gasifier [31]The chemical properties of CCwas studiedin order to obtain information regarding the relative pro-portions of the major elemental components of the materialand to predict the impact of these components on syngasquality and yield as well as on the environmental effects ofgasifying CC Table 5 shows the elemental components of CCas measured by the CHNS analyzer

The data in Table 5 shows that CC is composed of threemajor elements with a higher proportion of oxygen thancarbon The higher oxygen proportion is the reason for thelow energy value reported forCC in Section 35However thishigher oxygen content implies increased thermal reactivityduring gasification Increased biomass oxygen content is anindication of increased thermal reactivity of biomass duringthermochemical conversion processes the gasification ofbiomass is centered on carbon conversion [11]The content ofhydrogen is in agreement with most findings in the literatureand had positive contribution to the energy value of CCreported in Section 35 together with its content of carbonOxidation of carbon and hydrogen contents of biomass areusually initiated by exothermic reactions during gasificationforming CO

2and H

2O with the CO

2emitted as a product

of complete combustion [24]The relatively low nitrogen andsulfur contents imply lower amounts of NH

3 HCN and H

2S

(which are environmentally harmful compounds) may beanticipated during gasification

33 Metallic Elemental Components of Corn Cob In additionto nonmetallic elemental components of biomass there arealso metallic elemental components such as Na K Mg andSi that are especially responsible for the concentration of ashin biomass materials in other words the weight percentageof these metallic elements to an extent determines theoverall weight percentage of ash contained in biomass as highconcentration of these elements creates technical hitches suchas fouling sintering and slagging because of volatilization of

Table 6 Weight percentages of the metallic elemental componentsof corn cob

Element Composition (wt)Al 031K 153Si 044Na 132Ca 011Mg 042Fe 006

the elements which forms liquid slags on cooling when thebiomass is used as feedstock in gasification processes [32]Table 6 shows the weight percentages of themetallic elementscontained in CC which were obtained after analysis usinga Thermo Scientific Model ICE 3500 Atomic AbsorptionSpectrometer (AAS) equipped with hollow cathode lamps

It is quite obvious that the concentrations of the metallicelements are relatively low implying that there may be littleor no technical issues related to those previously mentionedwhen CC is used as feedstock in a gasification process Thereasons for the low concentration of these elements are thesame as those given for the high content of ash reported inTable 4 These ash-forming elements are usually taken up byplants during growth the elemental composition of biomassespecially with regard to the weight percentages of the ash-forming elements has key impact on ash transformationsequences and sintering behaviours [7 24] Ash-formingelements are usually characterized by complex transforma-tion reactions during biomass gasification creating technicalissues linked to those previously mentioned however reac-tions involving the oxides of calcium or magnesium withpotassium silicates lead to formation of high-temperature-melting calcium-magnesium-potassium silicates that playsignificant roles in the reduction of sintering issues duringgasification because of the limit in the formation of silicatesthat are rich in potassium [7 24 33 34] For fixed-bedgasification systems such as the downdraft system ash-related sintering proceeds with the formation of slag as aconsequence of certain factors like bridging coalescence andaccumulation of the sintered ash residues on gasifier gratesThe slag with large sizes cannot be transported out from thegrate which then interferes with the gasification process andreduces the performance of gasification appliances [35ndash37]

34 Reactive Components of Corn Cob To gain a deeperunderstanding of the chemistry of CC and to provide abaseline for the prediction of its gasification performance adiagnosis of the internal structure of thematerial is necessaryThis diagnosis relates to analysis of the materialrsquos reactivecomponents in terms of the functional groups present inits structure The spectrum associated with the structureof CC and the indicated peaks relative to each functionalgroup are presented in Figure 1 The absorbance at variouswavenumbers corresponds to the functional groups

6 Journal of Chemistry

102

101

100

99

98

97

96

95

94

Tran

smitt

ance

()

5000 4000 3000 2000 1000 0

Wavenumber (cmminus1)

Figure 1 FTIR spectrum of corn cob

0

20

40

60

80

100

0 200 400 600 800 1000

Wei

ght L

oss (

)

Temperature (∘C)

Figure 2 Thermogram resulting from the thermal analysis of corncob

It is quite obvious from Figure 1 that the peak at3303 cmminus1 corresponds to OndashH stretching vibrations thatindicates the presence of hydroxyl groups while that near2844 cmminus1 depicts CndashH stretching that corresponds to thepresence of alkanes 1000 cmminus1 depicts CndashO stretching withthe peak near 600 cmminus1 showing characteristics of CndashHbending These functional groups represent the chemicallyactive components of biomass that accelerates the rates of thegasification reactions presented in Section 1 [24]

Nonetheless for better understanding of the functionalgroups common to the structure of CC Table 7 presents thechemically active components related to the bonds of theatoms that make up the material and which take part duringthermal conversion processes

During gasification the presence of the ndashOH group willinitiate and accelerate the rate of condensation reactionscreated by dehydroxylation as a result of thermal decom-position of the cellulose content of the material caused byrising temperatures within the gasifier while CndashH presencedue to alkanes is connected to the reactions leading tohemicellulose degradation [24] The existence of the C=Cgroup which is an indication of the presence of alkenesfacilitates reactions leading to lignin decomposition whilethe group CndashO which is assigned to carboxylic groups in

Table 7 Functional groups present in the structure of corn cob

Frequencyrange(cmminus1)

Groups Class of compounds

3303 OndashH stretching Alcohol phenols2844 CndashH stretching Alkanes1589 C=C bending Aromatic compounds1029 CndashO stretching Alcohol phenols amp esters582 CndashH bending Aromatic compounds

cellulose and hemicellulose speeds up the rate of otherreactions such as decarboxylation reactions that leads to thebreakage of glycosidic bonds that consequently forms a seriesof less oxygen-containing compounds such as ethers acidsand aldehydes and noncondensable gases such as CO andCO2[24 38]

Plant photosynthesis is usually driven by energy from thesun that is usually stored in chemical bonds of the structuralcomponents of the plant implying that an amount of energywould be required to break these bonds in order to harnessthe energy which is mostly achieved through initiation ofgasification reactions when the plant material is to be usedas feedstock in a gasification process [11 28]

35 Energy Value of Corn Cob Plants convert energy fromthe sun into chemical energy that is stored in the structuralcomponents of the biomass by using CO

2in the atmosphere

[24] The energy value of CC was determined to evaluate theamount of energy available for conversion which is a veryimportant property of biomass because conversion efficiencyof a gasification process depends on it [11] In this study theenergy value of CC was measured as 1802MJkg a valuethat is in agreement with those reported by Danje 2011 andDanish et al 2015 [15 16] in Table 2 It is therefore sufficientto allude that the energy value of CC measured in this studyis in agreement with most findings in the literature

36Thermal Behaviour of CornCob In order to better under-stand the gasification characteristics of CC thermal analysisof the sample using an instrument relevant to gasification isnecessary This analysis is intended to establish the thermalbehaviour of the sample under both high and low tempera-tures as well as determine the thermal parameters that wouldinfluence its gasification Figure 2 shows the thermogramobtained from the thermogravimetric analysis of CC

The plot in Figure 2 shows that as temperature increasesthere is a marked reduction in the weight of the sample Theplot also shows that the thermal degradation behaviour of CCis characterized by three different weight loss stages with theinitial one at 94∘C which signifies the removal of moisturefrom the sample A significant weight loss could be observedbetween 200 and 500∘C and represents the second stage of thedecomposition process of the sample This may be attributedto the decomposition of basic organic components ofCC suchas cellulose hemicellulose and lignin the decomposition of

Journal of Chemistry 7

(a) (b)

(c) (d)

Figure 3 SEM images of corn cob obtained at different magnifications

these components releases volatile gases such as CO2and

CH4that are mainly formed due to the decomposition of

hemicellulose between the temperatures of 190 and 320∘CThis degradation temperature for hemicellulose implies lessproduction of tar and char during gasification of CC [24]The third stage of the thermal decomposition process ofCC is indicated by cellulose and lignin degradation between280 and 400∘C for cellulose and between 320 and 450∘C forlignin with total combustion of the sample taking place as itsweight is reduced in the process to give rise to decompositionof hydrocarbons During gasification cellulose and lignindegradation at higher temperatures depict the production ofcarbonized biomass as well as heavy organic and inorganiccompounds [39 40]

37 Microstructural Characteristics of Corn Cob The surfacestructure of CC was examined with a scanning electronmicroscopic instrument that offered detailed informationon imaging and surface composition of the sample Thisprovided a guide as to whether CC is enough carbonaceousmaterial suitable for gasification in a downdraft gasifierFigure 3 shows the SEM images of CC obtained at differ-ent magnifications The images were magnified by a factorof 250 for better understanding and interpretation of themicrostructural characteristics of the material

As can be seen from the images in Figures 3(a)ndash3(d) theshapes are quite irregular and agglomerated The sample is

clearly seen to have no pores even at higher magnificationsan evidence of lack of pretreatment prior to analysis butit exhibits cells on the surface without much characterizedstructure However at 250 magnification (Figure 3(a)) thereseem to be plenty of parallel lines that appear on the surface ofthe sample which look like cells of residual pith that providesa pathway for the transportation of water and nutrients fromthe soil but on increasing magnification to 500 (Figure 3(b))these lines seem to disappear showingmore vascular bundleswith not too conspicuous fragmented cells which indicatesfibrous lignocellulosic nature of CC which is a commonfeature of agricultural biomass residues [24] At higher mag-nification (times750 Figure 3(c)) the vascular bundles are morepronounced with the fragmented cell structures more visibleThepresence of the vascular bundles and cell structures are anindication of carbon-oriented structures which corroboratesthe carbon content data of CC presented in Table 5These cellstructures are also associated with the formation of pathwaysfor the production of gaseous products these features makeCC amenable to high temperature gasification that connotesoptimum efficiency [24 39 41] As image magnification wasincreased to a maximum of 1000 (Figure 3(d)) more featureswere revealed including the size of the vascular bundles andtheir compact nature which are important features used tounderstand the combustion behaviour of biomass materials[42]

8 Journal of Chemistry

4 Conclusions

In order to evaluate CC with regard to its gasification-relatedcharacteristics a detailed assessment based on fuel analysiswas performed The experiments conducted and the resultspresented showed that CC is a biomass feedstock suitablefor gasification due to its low moisture content and due toits low concentration of metallic elements However its highpercentage of ash may create a bit of technical challengesthat may lower gasification efficiency Its low concentrationof nitrogen and sulfur implies reduced emissions of NOXand SO

2during gasification and its hydrogen concentration

is high enough to initiate the water-gas shift reaction thatis the dominant chemical reaction which forms the majorportion of the syngas The energy value analysis showedthat CC contains a manageable amount of energy that canbe converted into useful energy through gasification Thereactive components of CC were mostly oxygen-containingfunctional groups that may play important roles duringgasification The study also established that the thermaldecomposition of CC began at temperatures below 100∘Cwith its complete degradation occurring at temperaturesclose to 1000∘C releasing enormous amount of gases whileSEM analysis revealed compacted vascular bundles and fibertissues linked to carbon-orientation that are among thefeatures of CC that may favour high temperature gasification

The results obtained form a significant basis for thedevelopment of a gasification system that would be tailoredto the demands of the characteristics of CC

Even though the CC used for this study exhibited lowconcentration of metallic elements an elevated weight per-centage of these elements is anticipated when the material isused as feedstock in a gasification process This is becauseof the high amount of ash recorded for CC The weightpercentage of the metallic elements of biomass increases withrising gasification temperature [24] As such further researchis required on reduction of the weight percentage of CCash content This study did not involve the gasification ofCC either via simulation or via experimental investigationof its gasification process This is where challenges could beexperienced with the use of CC It is therefore recommendedthat research be undertaken on the gasification of CC in orderto adequately establish the impact of fuel characteristics ongasification process efficiency The reaction kinetics of thethermal decomposition of CC also require further studies

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

The authors wish to acknowledge the financial support of theNational Research Foundation of South Africa (NRF) theGovanMbeki Research andDevelopment Center (GMRDC)and the Chemistry Department of both the University of FortHare and the Fort Hare Institute of Technology (FHIT) fortheir technical assistance

References

[1] D Gunarathne Optimization of the performance of downdraftbiomass gasifier installed at national engineering research anddevelopment (NERD) Centre of Sri Lanka [Msc thesis] KTHSchool of Industrial Engineering and Management Sweden2012

[2] Extension Farm Energy ldquoCorn cobs for biofuel productionrdquohttparticlesextensionorgpages26619corn-cobs-for-biofuel-production 2016

[3] J T Oladeji and C C Enweremadu ldquoA predictive model for thedetermination of some densification characteristics of corncobbriquettesrdquo inMaterials and Processes for Energy Communicat-ing Current Research and Technological Developments pp 169ndash177 2013

[4] Y Zhang A E Ghaly and B Li ldquoPhysical properties of cornresiduesrdquo American Journal of Biochemistry and Biotechnologyvol 8 no 2 pp 44ndash53 2012

[5] SA Department of Agriculture ldquoMaize productionrdquo httpndaagriczapublications 2016

[6] M Y Suberu A SMokhtar andN Bashir ldquoPotential capabilityof corn cob residue for small power generation in rural NigeriardquoARPN Journal of Engineering and Applied Sciences vol 7 no 8pp 1037ndash1046 2012

[7] L Wang J E Hustad and M Groslashnli ldquoSintering characteristicsand mineral transformation behaviors of corn cob ashesrdquoEnergy and Fuels vol 26 no 9 pp 5905ndash5916 2012

[8] J Lee ldquoBiological conversion of lignocellulosic biomass toethanolrdquo Journal of Biotechnology vol 56 no 1 pp 1ndash24 1997

[9] R N Andre F Pinto C Franco et al ldquoFluidised bed co-gasification of coal and olive oil industry wastesrdquo Fuel vol 84no 12-13 pp 1635ndash1644 2005

[10] J Fermoso Pressure co-gasification of coal and biomass for theproduction of hydrogen University of Oviedo Spain 2009

[11] A Anukam S Mamphweli E Meyer and O Okoh ldquoComputersimulation of the mass and energy balance during gasificationof sugarcane bagasserdquo Journal of Energy vol 2014 Article ID713054 9 pages 2014

[12] A Kumar L Wang Y A Dzenis D D Jones and M AHanna ldquoThermogravimetric characterization of corn stover asgasification and pyrolysis feedstockrdquo Biomass and Bioenergyvol 32 no 5 pp 460ndash467 2008

[13] K Arun and M V Ramanan ldquoExperimental studies on gasifi-cation of corn cob in a fixed bed systemrdquo Journal of Chemicaland Pharmaceutical Research vol 8 pp 667ndash676 2016

[14] A O Aboyade J F Gorgens M Carrier E L Meyer and JH Knoetze ldquoThermogravimetric study of the pyrolysis char-acteristics and kinetics of coal blends with corn and sugarcaneresiduesrdquo Fuel Processing Technology vol 106 pp 310ndash320 2013

[15] S Danje Fast pyrolysis of corn residues for energy production[dissertation thesis] Stellenbosch University 2011

[16] M Danish M Naqvi U Farooq and S Naqvi ldquoCharacteriza-tion of SouthAsian agricultural residues for potential utilisationin future energy mixrdquo Energy Procedia vol 75 pp 2974ndash29802015

[17] J Wannapeera N Worasuwannarak and S PipatmanomoildquoProduct yields and characteristics of rice husk rice straw andcorncob during fast pyrolysis in a drop-tubefixed-bed reactorrdquoSongklanakarin Journal of Science and Technology vol 30 no 3pp 393ndash404 2008

4 Journal of Chemistry

was examined by a fully computerized Perkin Elmer FTIRsystem which produces the absorbance spectra that demon-strate the unique chemical bonds and the atomic structureof the sample material This profile was in the form ofan absorption spectrum that indicated peaks representingcomponents in higher concentration Absorbance peaks onthe spectrum also indicated the functional groups Differenttypes of bonds and thus different functional groups absorbedinfrared radiation of various wavelengths Despite the factthat the analysis was performed in absorbance mode it canbe converted into a transmittance mode since they are justthe reverse of each other The analytical spectrum is thencontrasted in a reference library program with catalogedspectra to identify components for unknown material usingthe cataloged spectra for known materials

25 Thermogravimetric Analysis (TGA) The thermal behav-iour of biomass materials are usually measured by a thermo-gravimetric analyzer (TGA) which measures the percentageweight loss of the biomass as a function of temperature andthe resulting thermogram has a peculiar shape for biomassmaterials [25] In addition to studying the thermal behaviourof CC this analysis was undertaken in order to establish thethermal parameters that would impact on the gasification ofthe material It is worth noting that most TGA experimentsare conducted under a chemically inactive environment (ofwhich nitrogen or argon is often used) to show the effectof heat degradation that includes carbonization oxygen ishighly reactive and usually not recommended during analy-ses involving TGA because it reacts with sample componentsleading to loss of original sample in the process [24]

A 781mg of the sample was combusted in a SDT Q600TGA instrument under a nitrogen atmosphere at a flow rateof 35mLmin between 35 and 1000∘C Nitrogen was used tocreate a chemically inactive environment so as to preventthe TGA instrument from overheating A heating rate of20∘Cmin was used during TGA because this is characteristicof gasification systems using the downdraft gasifier [11]

26 SEMAnalysis Scanning ElectronMicroscopy (SEM) is ahigh resolution imaging system with an extraordinary depthof field It indicates topographical structural and elementaldata at lowmagnifications up to 200000x [26]Theutilizationof SEM innovation is a priceless guide in distinguishingand portraying mineral and material stages together withsurface components SEM in this study was used for surfacemorphological view of the material to establish if CC isenough carbonaceous material that would be suitable forgasification using the downdraft gasification system

The SEM analysis of CC was undertaken by a JEOL(JSM-6390) operating with accelerating voltage of 15 kVThe micrographs were generated at different magnifications(250ndash1000x) by a computer program The data was collectedover a selected area of the surface of the sample and atwo-dimensional image was generated that displayed spatialvariations in properties

Table 4 Measured physical characteristics of corn cob

Proximate analysis (wt)Moisture content 51Volatile matter content 651Ash content 85Fixed carbon 213

3 Results and Discussion

In this section the findings of this study are presenteddiscussed and substantiated with reference to existing datafrom the literature

31 Physical Characteristics of Corn Cob Gasifiers amongother factors operate satisfactorily with regard to efficiencyonly within certain ranges of feedstock characteristics [11]Table 4 shows the data obtained from the physical character-ization of CC which were obtained from the thermogravi-metric plot of the sample presented in Figure 2 employingthe equations presented in Table 3

From Table 4 moisture content of CC was measured as51 which is quite different when compared to the valuesreported in the literature It is lower than the value of 1174reported by Danish et al 2015 [16] and higher than thevalue of 46 reported by Danje 2011 [15] in Table 1 Thedifference in these values may be attributed to a numberof reasons including the source of the CC and handlingconditions However this value (51) for moisture content isdesirable for gasification to take place as materials with mois-ture content beyond 20 would create technical difficultieslinked to poor combustion conditions within the gasificationsystem andwill inhibit immediate combustion of thematerialat the same time increasing its smoking propensity witha consequent reduction in gasification process efficiency[24] It can also be noted that the CC used for this studyis characterized by relatively high volatile matter content(651) which was anticipated because of the organic natureof the material The contents of volatile matter in biomassmaterials are usually high due to the organic nature of thebiomass which indicates the biomass potential to create hugeamounts of inorganic vapours when used as feedstock in agasification process the higher the volatile matter contentof biomass the better its combustion and gasification ratesbecause of the biomass yield upon carbonization [25] Thematerial is also characterized by high ash content that mayalso be attributed to a number of factors that include thosepreviously given in Section 1 This high content of ash maynot be favourable to gasification because of issues linkedto sintering and slagging that may be experienced duringgasification which might also contribute to reduction inprocess efficiency Biomass ash content greater than 6 isnot desirable for gasification because it creates technicalissues related to agglomeration fouling and sintering as wellas slagging that may together reduce gasification efficiencyhowever ash may exert some catalytic effect that may allowfor cracking of higher molecular weight compounds such as

Journal of Chemistry 5

Table 5 Measured elemental components of corn cob

Ultimate analysis (wt)C 444H 56N 043S 13O (by difference) 4827

tar into lighter ones for optimum gasification efficiency [27ndash29] The fixed carbon content of CC was also found to beabout 21 which is high enough to allude that there will beincreased formation of char during gasification as the relativeproportions of the content of volatile matter and fixed carbonare related to the yields and composition of solid liquid andgaseous products formed during gasification [30]

32 Chemical Characteristics of Corn Cob The ratio of theproducts formed during gasification of biomass is influencednot just by its physical characteristics but also by the chemicalcomposition of the biomass fuel and the operating conditionsof the gasifier [31]The chemical properties of CCwas studiedin order to obtain information regarding the relative pro-portions of the major elemental components of the materialand to predict the impact of these components on syngasquality and yield as well as on the environmental effects ofgasifying CC Table 5 shows the elemental components of CCas measured by the CHNS analyzer

The data in Table 5 shows that CC is composed of threemajor elements with a higher proportion of oxygen thancarbon The higher oxygen proportion is the reason for thelow energy value reported forCC in Section 35However thishigher oxygen content implies increased thermal reactivityduring gasification Increased biomass oxygen content is anindication of increased thermal reactivity of biomass duringthermochemical conversion processes the gasification ofbiomass is centered on carbon conversion [11]The content ofhydrogen is in agreement with most findings in the literatureand had positive contribution to the energy value of CCreported in Section 35 together with its content of carbonOxidation of carbon and hydrogen contents of biomass areusually initiated by exothermic reactions during gasificationforming CO

2and H

2O with the CO

2emitted as a product

of complete combustion [24]The relatively low nitrogen andsulfur contents imply lower amounts of NH

3 HCN and H

2S

(which are environmentally harmful compounds) may beanticipated during gasification

33 Metallic Elemental Components of Corn Cob In additionto nonmetallic elemental components of biomass there arealso metallic elemental components such as Na K Mg andSi that are especially responsible for the concentration of ashin biomass materials in other words the weight percentageof these metallic elements to an extent determines theoverall weight percentage of ash contained in biomass as highconcentration of these elements creates technical hitches suchas fouling sintering and slagging because of volatilization of

Table 6 Weight percentages of the metallic elemental componentsof corn cob

Element Composition (wt)Al 031K 153Si 044Na 132Ca 011Mg 042Fe 006

the elements which forms liquid slags on cooling when thebiomass is used as feedstock in gasification processes [32]Table 6 shows the weight percentages of themetallic elementscontained in CC which were obtained after analysis usinga Thermo Scientific Model ICE 3500 Atomic AbsorptionSpectrometer (AAS) equipped with hollow cathode lamps

It is quite obvious that the concentrations of the metallicelements are relatively low implying that there may be littleor no technical issues related to those previously mentionedwhen CC is used as feedstock in a gasification process Thereasons for the low concentration of these elements are thesame as those given for the high content of ash reported inTable 4 These ash-forming elements are usually taken up byplants during growth the elemental composition of biomassespecially with regard to the weight percentages of the ash-forming elements has key impact on ash transformationsequences and sintering behaviours [7 24] Ash-formingelements are usually characterized by complex transforma-tion reactions during biomass gasification creating technicalissues linked to those previously mentioned however reac-tions involving the oxides of calcium or magnesium withpotassium silicates lead to formation of high-temperature-melting calcium-magnesium-potassium silicates that playsignificant roles in the reduction of sintering issues duringgasification because of the limit in the formation of silicatesthat are rich in potassium [7 24 33 34] For fixed-bedgasification systems such as the downdraft system ash-related sintering proceeds with the formation of slag as aconsequence of certain factors like bridging coalescence andaccumulation of the sintered ash residues on gasifier gratesThe slag with large sizes cannot be transported out from thegrate which then interferes with the gasification process andreduces the performance of gasification appliances [35ndash37]

34 Reactive Components of Corn Cob To gain a deeperunderstanding of the chemistry of CC and to provide abaseline for the prediction of its gasification performance adiagnosis of the internal structure of thematerial is necessaryThis diagnosis relates to analysis of the materialrsquos reactivecomponents in terms of the functional groups present inits structure The spectrum associated with the structureof CC and the indicated peaks relative to each functionalgroup are presented in Figure 1 The absorbance at variouswavenumbers corresponds to the functional groups

6 Journal of Chemistry

102

101

100

99

98

97

96

95

94

Tran

smitt

ance

()

5000 4000 3000 2000 1000 0

Wavenumber (cmminus1)

Figure 1 FTIR spectrum of corn cob

0

20

40

60

80

100

0 200 400 600 800 1000

Wei

ght L

oss (

)

Temperature (∘C)

Figure 2 Thermogram resulting from the thermal analysis of corncob

It is quite obvious from Figure 1 that the peak at3303 cmminus1 corresponds to OndashH stretching vibrations thatindicates the presence of hydroxyl groups while that near2844 cmminus1 depicts CndashH stretching that corresponds to thepresence of alkanes 1000 cmminus1 depicts CndashO stretching withthe peak near 600 cmminus1 showing characteristics of CndashHbending These functional groups represent the chemicallyactive components of biomass that accelerates the rates of thegasification reactions presented in Section 1 [24]

Nonetheless for better understanding of the functionalgroups common to the structure of CC Table 7 presents thechemically active components related to the bonds of theatoms that make up the material and which take part duringthermal conversion processes

During gasification the presence of the ndashOH group willinitiate and accelerate the rate of condensation reactionscreated by dehydroxylation as a result of thermal decom-position of the cellulose content of the material caused byrising temperatures within the gasifier while CndashH presencedue to alkanes is connected to the reactions leading tohemicellulose degradation [24] The existence of the C=Cgroup which is an indication of the presence of alkenesfacilitates reactions leading to lignin decomposition whilethe group CndashO which is assigned to carboxylic groups in

Table 7 Functional groups present in the structure of corn cob

Frequencyrange(cmminus1)

Groups Class of compounds

3303 OndashH stretching Alcohol phenols2844 CndashH stretching Alkanes1589 C=C bending Aromatic compounds1029 CndashO stretching Alcohol phenols amp esters582 CndashH bending Aromatic compounds

cellulose and hemicellulose speeds up the rate of otherreactions such as decarboxylation reactions that leads to thebreakage of glycosidic bonds that consequently forms a seriesof less oxygen-containing compounds such as ethers acidsand aldehydes and noncondensable gases such as CO andCO2[24 38]

Plant photosynthesis is usually driven by energy from thesun that is usually stored in chemical bonds of the structuralcomponents of the plant implying that an amount of energywould be required to break these bonds in order to harnessthe energy which is mostly achieved through initiation ofgasification reactions when the plant material is to be usedas feedstock in a gasification process [11 28]

35 Energy Value of Corn Cob Plants convert energy fromthe sun into chemical energy that is stored in the structuralcomponents of the biomass by using CO

2in the atmosphere

[24] The energy value of CC was determined to evaluate theamount of energy available for conversion which is a veryimportant property of biomass because conversion efficiencyof a gasification process depends on it [11] In this study theenergy value of CC was measured as 1802MJkg a valuethat is in agreement with those reported by Danje 2011 andDanish et al 2015 [15 16] in Table 2 It is therefore sufficientto allude that the energy value of CC measured in this studyis in agreement with most findings in the literature

36Thermal Behaviour of CornCob In order to better under-stand the gasification characteristics of CC thermal analysisof the sample using an instrument relevant to gasification isnecessary This analysis is intended to establish the thermalbehaviour of the sample under both high and low tempera-tures as well as determine the thermal parameters that wouldinfluence its gasification Figure 2 shows the thermogramobtained from the thermogravimetric analysis of CC

The plot in Figure 2 shows that as temperature increasesthere is a marked reduction in the weight of the sample Theplot also shows that the thermal degradation behaviour of CCis characterized by three different weight loss stages with theinitial one at 94∘C which signifies the removal of moisturefrom the sample A significant weight loss could be observedbetween 200 and 500∘C and represents the second stage of thedecomposition process of the sample This may be attributedto the decomposition of basic organic components ofCC suchas cellulose hemicellulose and lignin the decomposition of

Journal of Chemistry 7

(a) (b)

(c) (d)

Figure 3 SEM images of corn cob obtained at different magnifications

these components releases volatile gases such as CO2and

CH4that are mainly formed due to the decomposition of

hemicellulose between the temperatures of 190 and 320∘CThis degradation temperature for hemicellulose implies lessproduction of tar and char during gasification of CC [24]The third stage of the thermal decomposition process ofCC is indicated by cellulose and lignin degradation between280 and 400∘C for cellulose and between 320 and 450∘C forlignin with total combustion of the sample taking place as itsweight is reduced in the process to give rise to decompositionof hydrocarbons During gasification cellulose and lignindegradation at higher temperatures depict the production ofcarbonized biomass as well as heavy organic and inorganiccompounds [39 40]

37 Microstructural Characteristics of Corn Cob The surfacestructure of CC was examined with a scanning electronmicroscopic instrument that offered detailed informationon imaging and surface composition of the sample Thisprovided a guide as to whether CC is enough carbonaceousmaterial suitable for gasification in a downdraft gasifierFigure 3 shows the SEM images of CC obtained at differ-ent magnifications The images were magnified by a factorof 250 for better understanding and interpretation of themicrostructural characteristics of the material

As can be seen from the images in Figures 3(a)ndash3(d) theshapes are quite irregular and agglomerated The sample is

clearly seen to have no pores even at higher magnificationsan evidence of lack of pretreatment prior to analysis butit exhibits cells on the surface without much characterizedstructure However at 250 magnification (Figure 3(a)) thereseem to be plenty of parallel lines that appear on the surface ofthe sample which look like cells of residual pith that providesa pathway for the transportation of water and nutrients fromthe soil but on increasing magnification to 500 (Figure 3(b))these lines seem to disappear showingmore vascular bundleswith not too conspicuous fragmented cells which indicatesfibrous lignocellulosic nature of CC which is a commonfeature of agricultural biomass residues [24] At higher mag-nification (times750 Figure 3(c)) the vascular bundles are morepronounced with the fragmented cell structures more visibleThepresence of the vascular bundles and cell structures are anindication of carbon-oriented structures which corroboratesthe carbon content data of CC presented in Table 5These cellstructures are also associated with the formation of pathwaysfor the production of gaseous products these features makeCC amenable to high temperature gasification that connotesoptimum efficiency [24 39 41] As image magnification wasincreased to a maximum of 1000 (Figure 3(d)) more featureswere revealed including the size of the vascular bundles andtheir compact nature which are important features used tounderstand the combustion behaviour of biomass materials[42]

8 Journal of Chemistry

4 Conclusions

In order to evaluate CC with regard to its gasification-relatedcharacteristics a detailed assessment based on fuel analysiswas performed The experiments conducted and the resultspresented showed that CC is a biomass feedstock suitablefor gasification due to its low moisture content and due toits low concentration of metallic elements However its highpercentage of ash may create a bit of technical challengesthat may lower gasification efficiency Its low concentrationof nitrogen and sulfur implies reduced emissions of NOXand SO

2during gasification and its hydrogen concentration

is high enough to initiate the water-gas shift reaction thatis the dominant chemical reaction which forms the majorportion of the syngas The energy value analysis showedthat CC contains a manageable amount of energy that canbe converted into useful energy through gasification Thereactive components of CC were mostly oxygen-containingfunctional groups that may play important roles duringgasification The study also established that the thermaldecomposition of CC began at temperatures below 100∘Cwith its complete degradation occurring at temperaturesclose to 1000∘C releasing enormous amount of gases whileSEM analysis revealed compacted vascular bundles and fibertissues linked to carbon-orientation that are among thefeatures of CC that may favour high temperature gasification

The results obtained form a significant basis for thedevelopment of a gasification system that would be tailoredto the demands of the characteristics of CC

Even though the CC used for this study exhibited lowconcentration of metallic elements an elevated weight per-centage of these elements is anticipated when the material isused as feedstock in a gasification process This is becauseof the high amount of ash recorded for CC The weightpercentage of the metallic elements of biomass increases withrising gasification temperature [24] As such further researchis required on reduction of the weight percentage of CCash content This study did not involve the gasification ofCC either via simulation or via experimental investigationof its gasification process This is where challenges could beexperienced with the use of CC It is therefore recommendedthat research be undertaken on the gasification of CC in orderto adequately establish the impact of fuel characteristics ongasification process efficiency The reaction kinetics of thethermal decomposition of CC also require further studies

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

The authors wish to acknowledge the financial support of theNational Research Foundation of South Africa (NRF) theGovanMbeki Research andDevelopment Center (GMRDC)and the Chemistry Department of both the University of FortHare and the Fort Hare Institute of Technology (FHIT) fortheir technical assistance

References

[1] D Gunarathne Optimization of the performance of downdraftbiomass gasifier installed at national engineering research anddevelopment (NERD) Centre of Sri Lanka [Msc thesis] KTHSchool of Industrial Engineering and Management Sweden2012

[2] Extension Farm Energy ldquoCorn cobs for biofuel productionrdquohttparticlesextensionorgpages26619corn-cobs-for-biofuel-production 2016

[3] J T Oladeji and C C Enweremadu ldquoA predictive model for thedetermination of some densification characteristics of corncobbriquettesrdquo inMaterials and Processes for Energy Communicat-ing Current Research and Technological Developments pp 169ndash177 2013

[4] Y Zhang A E Ghaly and B Li ldquoPhysical properties of cornresiduesrdquo American Journal of Biochemistry and Biotechnologyvol 8 no 2 pp 44ndash53 2012

[5] SA Department of Agriculture ldquoMaize productionrdquo httpndaagriczapublications 2016

[6] M Y Suberu A SMokhtar andN Bashir ldquoPotential capabilityof corn cob residue for small power generation in rural NigeriardquoARPN Journal of Engineering and Applied Sciences vol 7 no 8pp 1037ndash1046 2012

[7] L Wang J E Hustad and M Groslashnli ldquoSintering characteristicsand mineral transformation behaviors of corn cob ashesrdquoEnergy and Fuels vol 26 no 9 pp 5905ndash5916 2012

[8] J Lee ldquoBiological conversion of lignocellulosic biomass toethanolrdquo Journal of Biotechnology vol 56 no 1 pp 1ndash24 1997

[9] R N Andre F Pinto C Franco et al ldquoFluidised bed co-gasification of coal and olive oil industry wastesrdquo Fuel vol 84no 12-13 pp 1635ndash1644 2005

[10] J Fermoso Pressure co-gasification of coal and biomass for theproduction of hydrogen University of Oviedo Spain 2009

[11] A Anukam S Mamphweli E Meyer and O Okoh ldquoComputersimulation of the mass and energy balance during gasificationof sugarcane bagasserdquo Journal of Energy vol 2014 Article ID713054 9 pages 2014

[12] A Kumar L Wang Y A Dzenis D D Jones and M AHanna ldquoThermogravimetric characterization of corn stover asgasification and pyrolysis feedstockrdquo Biomass and Bioenergyvol 32 no 5 pp 460ndash467 2008

[13] K Arun and M V Ramanan ldquoExperimental studies on gasifi-cation of corn cob in a fixed bed systemrdquo Journal of Chemicaland Pharmaceutical Research vol 8 pp 667ndash676 2016

[14] A O Aboyade J F Gorgens M Carrier E L Meyer and JH Knoetze ldquoThermogravimetric study of the pyrolysis char-acteristics and kinetics of coal blends with corn and sugarcaneresiduesrdquo Fuel Processing Technology vol 106 pp 310ndash320 2013

[15] S Danje Fast pyrolysis of corn residues for energy production[dissertation thesis] Stellenbosch University 2011

[16] M Danish M Naqvi U Farooq and S Naqvi ldquoCharacteriza-tion of SouthAsian agricultural residues for potential utilisationin future energy mixrdquo Energy Procedia vol 75 pp 2974ndash29802015

[17] J Wannapeera N Worasuwannarak and S PipatmanomoildquoProduct yields and characteristics of rice husk rice straw andcorncob during fast pyrolysis in a drop-tubefixed-bed reactorrdquoSongklanakarin Journal of Science and Technology vol 30 no 3pp 393ndash404 2008

Journal of Chemistry 5

Table 5 Measured elemental components of corn cob

Ultimate analysis (wt)C 444H 56N 043S 13O (by difference) 4827

tar into lighter ones for optimum gasification efficiency [27ndash29] The fixed carbon content of CC was also found to beabout 21 which is high enough to allude that there will beincreased formation of char during gasification as the relativeproportions of the content of volatile matter and fixed carbonare related to the yields and composition of solid liquid andgaseous products formed during gasification [30]

32 Chemical Characteristics of Corn Cob The ratio of theproducts formed during gasification of biomass is influencednot just by its physical characteristics but also by the chemicalcomposition of the biomass fuel and the operating conditionsof the gasifier [31]The chemical properties of CCwas studiedin order to obtain information regarding the relative pro-portions of the major elemental components of the materialand to predict the impact of these components on syngasquality and yield as well as on the environmental effects ofgasifying CC Table 5 shows the elemental components of CCas measured by the CHNS analyzer

The data in Table 5 shows that CC is composed of threemajor elements with a higher proportion of oxygen thancarbon The higher oxygen proportion is the reason for thelow energy value reported forCC in Section 35However thishigher oxygen content implies increased thermal reactivityduring gasification Increased biomass oxygen content is anindication of increased thermal reactivity of biomass duringthermochemical conversion processes the gasification ofbiomass is centered on carbon conversion [11]The content ofhydrogen is in agreement with most findings in the literatureand had positive contribution to the energy value of CCreported in Section 35 together with its content of carbonOxidation of carbon and hydrogen contents of biomass areusually initiated by exothermic reactions during gasificationforming CO

2and H

2O with the CO

2emitted as a product

of complete combustion [24]The relatively low nitrogen andsulfur contents imply lower amounts of NH

3 HCN and H

2S

(which are environmentally harmful compounds) may beanticipated during gasification

33 Metallic Elemental Components of Corn Cob In additionto nonmetallic elemental components of biomass there arealso metallic elemental components such as Na K Mg andSi that are especially responsible for the concentration of ashin biomass materials in other words the weight percentageof these metallic elements to an extent determines theoverall weight percentage of ash contained in biomass as highconcentration of these elements creates technical hitches suchas fouling sintering and slagging because of volatilization of

Table 6 Weight percentages of the metallic elemental componentsof corn cob

Element Composition (wt)Al 031K 153Si 044Na 132Ca 011Mg 042Fe 006

the elements which forms liquid slags on cooling when thebiomass is used as feedstock in gasification processes [32]Table 6 shows the weight percentages of themetallic elementscontained in CC which were obtained after analysis usinga Thermo Scientific Model ICE 3500 Atomic AbsorptionSpectrometer (AAS) equipped with hollow cathode lamps

It is quite obvious that the concentrations of the metallicelements are relatively low implying that there may be littleor no technical issues related to those previously mentionedwhen CC is used as feedstock in a gasification process Thereasons for the low concentration of these elements are thesame as those given for the high content of ash reported inTable 4 These ash-forming elements are usually taken up byplants during growth the elemental composition of biomassespecially with regard to the weight percentages of the ash-forming elements has key impact on ash transformationsequences and sintering behaviours [7 24] Ash-formingelements are usually characterized by complex transforma-tion reactions during biomass gasification creating technicalissues linked to those previously mentioned however reac-tions involving the oxides of calcium or magnesium withpotassium silicates lead to formation of high-temperature-melting calcium-magnesium-potassium silicates that playsignificant roles in the reduction of sintering issues duringgasification because of the limit in the formation of silicatesthat are rich in potassium [7 24 33 34] For fixed-bedgasification systems such as the downdraft system ash-related sintering proceeds with the formation of slag as aconsequence of certain factors like bridging coalescence andaccumulation of the sintered ash residues on gasifier gratesThe slag with large sizes cannot be transported out from thegrate which then interferes with the gasification process andreduces the performance of gasification appliances [35ndash37]

34 Reactive Components of Corn Cob To gain a deeperunderstanding of the chemistry of CC and to provide abaseline for the prediction of its gasification performance adiagnosis of the internal structure of thematerial is necessaryThis diagnosis relates to analysis of the materialrsquos reactivecomponents in terms of the functional groups present inits structure The spectrum associated with the structureof CC and the indicated peaks relative to each functionalgroup are presented in Figure 1 The absorbance at variouswavenumbers corresponds to the functional groups

6 Journal of Chemistry

102

101

100

99

98

97

96

95

94

Tran

smitt

ance

()

5000 4000 3000 2000 1000 0

Wavenumber (cmminus1)

Figure 1 FTIR spectrum of corn cob

0

20

40

60

80

100

0 200 400 600 800 1000

Wei

ght L

oss (

)

Temperature (∘C)

Figure 2 Thermogram resulting from the thermal analysis of corncob

It is quite obvious from Figure 1 that the peak at3303 cmminus1 corresponds to OndashH stretching vibrations thatindicates the presence of hydroxyl groups while that near2844 cmminus1 depicts CndashH stretching that corresponds to thepresence of alkanes 1000 cmminus1 depicts CndashO stretching withthe peak near 600 cmminus1 showing characteristics of CndashHbending These functional groups represent the chemicallyactive components of biomass that accelerates the rates of thegasification reactions presented in Section 1 [24]

Nonetheless for better understanding of the functionalgroups common to the structure of CC Table 7 presents thechemically active components related to the bonds of theatoms that make up the material and which take part duringthermal conversion processes

During gasification the presence of the ndashOH group willinitiate and accelerate the rate of condensation reactionscreated by dehydroxylation as a result of thermal decom-position of the cellulose content of the material caused byrising temperatures within the gasifier while CndashH presencedue to alkanes is connected to the reactions leading tohemicellulose degradation [24] The existence of the C=Cgroup which is an indication of the presence of alkenesfacilitates reactions leading to lignin decomposition whilethe group CndashO which is assigned to carboxylic groups in

Table 7 Functional groups present in the structure of corn cob

Frequencyrange(cmminus1)

Groups Class of compounds

3303 OndashH stretching Alcohol phenols2844 CndashH stretching Alkanes1589 C=C bending Aromatic compounds1029 CndashO stretching Alcohol phenols amp esters582 CndashH bending Aromatic compounds

cellulose and hemicellulose speeds up the rate of otherreactions such as decarboxylation reactions that leads to thebreakage of glycosidic bonds that consequently forms a seriesof less oxygen-containing compounds such as ethers acidsand aldehydes and noncondensable gases such as CO andCO2[24 38]

Plant photosynthesis is usually driven by energy from thesun that is usually stored in chemical bonds of the structuralcomponents of the plant implying that an amount of energywould be required to break these bonds in order to harnessthe energy which is mostly achieved through initiation ofgasification reactions when the plant material is to be usedas feedstock in a gasification process [11 28]

35 Energy Value of Corn Cob Plants convert energy fromthe sun into chemical energy that is stored in the structuralcomponents of the biomass by using CO

2in the atmosphere

[24] The energy value of CC was determined to evaluate theamount of energy available for conversion which is a veryimportant property of biomass because conversion efficiencyof a gasification process depends on it [11] In this study theenergy value of CC was measured as 1802MJkg a valuethat is in agreement with those reported by Danje 2011 andDanish et al 2015 [15 16] in Table 2 It is therefore sufficientto allude that the energy value of CC measured in this studyis in agreement with most findings in the literature

36Thermal Behaviour of CornCob In order to better under-stand the gasification characteristics of CC thermal analysisof the sample using an instrument relevant to gasification isnecessary This analysis is intended to establish the thermalbehaviour of the sample under both high and low tempera-tures as well as determine the thermal parameters that wouldinfluence its gasification Figure 2 shows the thermogramobtained from the thermogravimetric analysis of CC

The plot in Figure 2 shows that as temperature increasesthere is a marked reduction in the weight of the sample Theplot also shows that the thermal degradation behaviour of CCis characterized by three different weight loss stages with theinitial one at 94∘C which signifies the removal of moisturefrom the sample A significant weight loss could be observedbetween 200 and 500∘C and represents the second stage of thedecomposition process of the sample This may be attributedto the decomposition of basic organic components ofCC suchas cellulose hemicellulose and lignin the decomposition of

Journal of Chemistry 7

(a) (b)

(c) (d)

Figure 3 SEM images of corn cob obtained at different magnifications

these components releases volatile gases such as CO2and

CH4that are mainly formed due to the decomposition of

hemicellulose between the temperatures of 190 and 320∘CThis degradation temperature for hemicellulose implies lessproduction of tar and char during gasification of CC [24]The third stage of the thermal decomposition process ofCC is indicated by cellulose and lignin degradation between280 and 400∘C for cellulose and between 320 and 450∘C forlignin with total combustion of the sample taking place as itsweight is reduced in the process to give rise to decompositionof hydrocarbons During gasification cellulose and lignindegradation at higher temperatures depict the production ofcarbonized biomass as well as heavy organic and inorganiccompounds [39 40]

37 Microstructural Characteristics of Corn Cob The surfacestructure of CC was examined with a scanning electronmicroscopic instrument that offered detailed informationon imaging and surface composition of the sample Thisprovided a guide as to whether CC is enough carbonaceousmaterial suitable for gasification in a downdraft gasifierFigure 3 shows the SEM images of CC obtained at differ-ent magnifications The images were magnified by a factorof 250 for better understanding and interpretation of themicrostructural characteristics of the material

As can be seen from the images in Figures 3(a)ndash3(d) theshapes are quite irregular and agglomerated The sample is

clearly seen to have no pores even at higher magnificationsan evidence of lack of pretreatment prior to analysis butit exhibits cells on the surface without much characterizedstructure However at 250 magnification (Figure 3(a)) thereseem to be plenty of parallel lines that appear on the surface ofthe sample which look like cells of residual pith that providesa pathway for the transportation of water and nutrients fromthe soil but on increasing magnification to 500 (Figure 3(b))these lines seem to disappear showingmore vascular bundleswith not too conspicuous fragmented cells which indicatesfibrous lignocellulosic nature of CC which is a commonfeature of agricultural biomass residues [24] At higher mag-nification (times750 Figure 3(c)) the vascular bundles are morepronounced with the fragmented cell structures more visibleThepresence of the vascular bundles and cell structures are anindication of carbon-oriented structures which corroboratesthe carbon content data of CC presented in Table 5These cellstructures are also associated with the formation of pathwaysfor the production of gaseous products these features makeCC amenable to high temperature gasification that connotesoptimum efficiency [24 39 41] As image magnification wasincreased to a maximum of 1000 (Figure 3(d)) more featureswere revealed including the size of the vascular bundles andtheir compact nature which are important features used tounderstand the combustion behaviour of biomass materials[42]

8 Journal of Chemistry

4 Conclusions

In order to evaluate CC with regard to its gasification-relatedcharacteristics a detailed assessment based on fuel analysiswas performed The experiments conducted and the resultspresented showed that CC is a biomass feedstock suitablefor gasification due to its low moisture content and due toits low concentration of metallic elements However its highpercentage of ash may create a bit of technical challengesthat may lower gasification efficiency Its low concentrationof nitrogen and sulfur implies reduced emissions of NOXand SO

2during gasification and its hydrogen concentration

is high enough to initiate the water-gas shift reaction thatis the dominant chemical reaction which forms the majorportion of the syngas The energy value analysis showedthat CC contains a manageable amount of energy that canbe converted into useful energy through gasification Thereactive components of CC were mostly oxygen-containingfunctional groups that may play important roles duringgasification The study also established that the thermaldecomposition of CC began at temperatures below 100∘Cwith its complete degradation occurring at temperaturesclose to 1000∘C releasing enormous amount of gases whileSEM analysis revealed compacted vascular bundles and fibertissues linked to carbon-orientation that are among thefeatures of CC that may favour high temperature gasification

The results obtained form a significant basis for thedevelopment of a gasification system that would be tailoredto the demands of the characteristics of CC

Even though the CC used for this study exhibited lowconcentration of metallic elements an elevated weight per-centage of these elements is anticipated when the material isused as feedstock in a gasification process This is becauseof the high amount of ash recorded for CC The weightpercentage of the metallic elements of biomass increases withrising gasification temperature [24] As such further researchis required on reduction of the weight percentage of CCash content This study did not involve the gasification ofCC either via simulation or via experimental investigationof its gasification process This is where challenges could beexperienced with the use of CC It is therefore recommendedthat research be undertaken on the gasification of CC in orderto adequately establish the impact of fuel characteristics ongasification process efficiency The reaction kinetics of thethermal decomposition of CC also require further studies

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

The authors wish to acknowledge the financial support of theNational Research Foundation of South Africa (NRF) theGovanMbeki Research andDevelopment Center (GMRDC)and the Chemistry Department of both the University of FortHare and the Fort Hare Institute of Technology (FHIT) fortheir technical assistance

References

[1] D Gunarathne Optimization of the performance of downdraftbiomass gasifier installed at national engineering research anddevelopment (NERD) Centre of Sri Lanka [Msc thesis] KTHSchool of Industrial Engineering and Management Sweden2012

[2] Extension Farm Energy ldquoCorn cobs for biofuel productionrdquohttparticlesextensionorgpages26619corn-cobs-for-biofuel-production 2016

[3] J T Oladeji and C C Enweremadu ldquoA predictive model for thedetermination of some densification characteristics of corncobbriquettesrdquo inMaterials and Processes for Energy Communicat-ing Current Research and Technological Developments pp 169ndash177 2013

[4] Y Zhang A E Ghaly and B Li ldquoPhysical properties of cornresiduesrdquo American Journal of Biochemistry and Biotechnologyvol 8 no 2 pp 44ndash53 2012

[5] SA Department of Agriculture ldquoMaize productionrdquo httpndaagriczapublications 2016

[6] M Y Suberu A SMokhtar andN Bashir ldquoPotential capabilityof corn cob residue for small power generation in rural NigeriardquoARPN Journal of Engineering and Applied Sciences vol 7 no 8pp 1037ndash1046 2012

[7] L Wang J E Hustad and M Groslashnli ldquoSintering characteristicsand mineral transformation behaviors of corn cob ashesrdquoEnergy and Fuels vol 26 no 9 pp 5905ndash5916 2012

[8] J Lee ldquoBiological conversion of lignocellulosic biomass toethanolrdquo Journal of Biotechnology vol 56 no 1 pp 1ndash24 1997

[9] R N Andre F Pinto C Franco et al ldquoFluidised bed co-gasification of coal and olive oil industry wastesrdquo Fuel vol 84no 12-13 pp 1635ndash1644 2005

[10] J Fermoso Pressure co-gasification of coal and biomass for theproduction of hydrogen University of Oviedo Spain 2009

[11] A Anukam S Mamphweli E Meyer and O Okoh ldquoComputersimulation of the mass and energy balance during gasificationof sugarcane bagasserdquo Journal of Energy vol 2014 Article ID713054 9 pages 2014

[12] A Kumar L Wang Y A Dzenis D D Jones and M AHanna ldquoThermogravimetric characterization of corn stover asgasification and pyrolysis feedstockrdquo Biomass and Bioenergyvol 32 no 5 pp 460ndash467 2008

[13] K Arun and M V Ramanan ldquoExperimental studies on gasifi-cation of corn cob in a fixed bed systemrdquo Journal of Chemicaland Pharmaceutical Research vol 8 pp 667ndash676 2016

[14] A O Aboyade J F Gorgens M Carrier E L Meyer and JH Knoetze ldquoThermogravimetric study of the pyrolysis char-acteristics and kinetics of coal blends with corn and sugarcaneresiduesrdquo Fuel Processing Technology vol 106 pp 310ndash320 2013

[15] S Danje Fast pyrolysis of corn residues for energy production[dissertation thesis] Stellenbosch University 2011

[16] M Danish M Naqvi U Farooq and S Naqvi ldquoCharacteriza-tion of SouthAsian agricultural residues for potential utilisationin future energy mixrdquo Energy Procedia vol 75 pp 2974ndash29802015

[17] J Wannapeera N Worasuwannarak and S PipatmanomoildquoProduct yields and characteristics of rice husk rice straw andcorncob during fast pyrolysis in a drop-tubefixed-bed reactorrdquoSongklanakarin Journal of Science and Technology vol 30 no 3pp 393ndash404 2008

6 Journal of Chemistry

102

101

100

99

98

97

96

95

94

Tran

smitt

ance

()

5000 4000 3000 2000 1000 0

Wavenumber (cmminus1)

Figure 1 FTIR spectrum of corn cob

0

20

40

60

80

100

0 200 400 600 800 1000

Wei

ght L

oss (

)

Temperature (∘C)

Figure 2 Thermogram resulting from the thermal analysis of corncob

It is quite obvious from Figure 1 that the peak at3303 cmminus1 corresponds to OndashH stretching vibrations thatindicates the presence of hydroxyl groups while that near2844 cmminus1 depicts CndashH stretching that corresponds to thepresence of alkanes 1000 cmminus1 depicts CndashO stretching withthe peak near 600 cmminus1 showing characteristics of CndashHbending These functional groups represent the chemicallyactive components of biomass that accelerates the rates of thegasification reactions presented in Section 1 [24]

Nonetheless for better understanding of the functionalgroups common to the structure of CC Table 7 presents thechemically active components related to the bonds of theatoms that make up the material and which take part duringthermal conversion processes

During gasification the presence of the ndashOH group willinitiate and accelerate the rate of condensation reactionscreated by dehydroxylation as a result of thermal decom-position of the cellulose content of the material caused byrising temperatures within the gasifier while CndashH presencedue to alkanes is connected to the reactions leading tohemicellulose degradation [24] The existence of the C=Cgroup which is an indication of the presence of alkenesfacilitates reactions leading to lignin decomposition whilethe group CndashO which is assigned to carboxylic groups in

Table 7 Functional groups present in the structure of corn cob

Frequencyrange(cmminus1)

Groups Class of compounds

3303 OndashH stretching Alcohol phenols2844 CndashH stretching Alkanes1589 C=C bending Aromatic compounds1029 CndashO stretching Alcohol phenols amp esters582 CndashH bending Aromatic compounds

cellulose and hemicellulose speeds up the rate of otherreactions such as decarboxylation reactions that leads to thebreakage of glycosidic bonds that consequently forms a seriesof less oxygen-containing compounds such as ethers acidsand aldehydes and noncondensable gases such as CO andCO2[24 38]

Plant photosynthesis is usually driven by energy from thesun that is usually stored in chemical bonds of the structuralcomponents of the plant implying that an amount of energywould be required to break these bonds in order to harnessthe energy which is mostly achieved through initiation ofgasification reactions when the plant material is to be usedas feedstock in a gasification process [11 28]

35 Energy Value of Corn Cob Plants convert energy fromthe sun into chemical energy that is stored in the structuralcomponents of the biomass by using CO

2in the atmosphere

[24] The energy value of CC was determined to evaluate theamount of energy available for conversion which is a veryimportant property of biomass because conversion efficiencyof a gasification process depends on it [11] In this study theenergy value of CC was measured as 1802MJkg a valuethat is in agreement with those reported by Danje 2011 andDanish et al 2015 [15 16] in Table 2 It is therefore sufficientto allude that the energy value of CC measured in this studyis in agreement with most findings in the literature

36Thermal Behaviour of CornCob In order to better under-stand the gasification characteristics of CC thermal analysisof the sample using an instrument relevant to gasification isnecessary This analysis is intended to establish the thermalbehaviour of the sample under both high and low tempera-tures as well as determine the thermal parameters that wouldinfluence its gasification Figure 2 shows the thermogramobtained from the thermogravimetric analysis of CC

The plot in Figure 2 shows that as temperature increasesthere is a marked reduction in the weight of the sample Theplot also shows that the thermal degradation behaviour of CCis characterized by three different weight loss stages with theinitial one at 94∘C which signifies the removal of moisturefrom the sample A significant weight loss could be observedbetween 200 and 500∘C and represents the second stage of thedecomposition process of the sample This may be attributedto the decomposition of basic organic components ofCC suchas cellulose hemicellulose and lignin the decomposition of

Journal of Chemistry 7

(a) (b)

(c) (d)

Figure 3 SEM images of corn cob obtained at different magnifications

these components releases volatile gases such as CO2and

CH4that are mainly formed due to the decomposition of

hemicellulose between the temperatures of 190 and 320∘CThis degradation temperature for hemicellulose implies lessproduction of tar and char during gasification of CC [24]The third stage of the thermal decomposition process ofCC is indicated by cellulose and lignin degradation between280 and 400∘C for cellulose and between 320 and 450∘C forlignin with total combustion of the sample taking place as itsweight is reduced in the process to give rise to decompositionof hydrocarbons During gasification cellulose and lignindegradation at higher temperatures depict the production ofcarbonized biomass as well as heavy organic and inorganiccompounds [39 40]

37 Microstructural Characteristics of Corn Cob The surfacestructure of CC was examined with a scanning electronmicroscopic instrument that offered detailed informationon imaging and surface composition of the sample Thisprovided a guide as to whether CC is enough carbonaceousmaterial suitable for gasification in a downdraft gasifierFigure 3 shows the SEM images of CC obtained at differ-ent magnifications The images were magnified by a factorof 250 for better understanding and interpretation of themicrostructural characteristics of the material

As can be seen from the images in Figures 3(a)ndash3(d) theshapes are quite irregular and agglomerated The sample is

clearly seen to have no pores even at higher magnificationsan evidence of lack of pretreatment prior to analysis butit exhibits cells on the surface without much characterizedstructure However at 250 magnification (Figure 3(a)) thereseem to be plenty of parallel lines that appear on the surface ofthe sample which look like cells of residual pith that providesa pathway for the transportation of water and nutrients fromthe soil but on increasing magnification to 500 (Figure 3(b))these lines seem to disappear showingmore vascular bundleswith not too conspicuous fragmented cells which indicatesfibrous lignocellulosic nature of CC which is a commonfeature of agricultural biomass residues [24] At higher mag-nification (times750 Figure 3(c)) the vascular bundles are morepronounced with the fragmented cell structures more visibleThepresence of the vascular bundles and cell structures are anindication of carbon-oriented structures which corroboratesthe carbon content data of CC presented in Table 5These cellstructures are also associated with the formation of pathwaysfor the production of gaseous products these features makeCC amenable to high temperature gasification that connotesoptimum efficiency [24 39 41] As image magnification wasincreased to a maximum of 1000 (Figure 3(d)) more featureswere revealed including the size of the vascular bundles andtheir compact nature which are important features used tounderstand the combustion behaviour of biomass materials[42]

8 Journal of Chemistry

4 Conclusions

In order to evaluate CC with regard to its gasification-relatedcharacteristics a detailed assessment based on fuel analysiswas performed The experiments conducted and the resultspresented showed that CC is a biomass feedstock suitablefor gasification due to its low moisture content and due toits low concentration of metallic elements However its highpercentage of ash may create a bit of technical challengesthat may lower gasification efficiency Its low concentrationof nitrogen and sulfur implies reduced emissions of NOXand SO

2during gasification and its hydrogen concentration

is high enough to initiate the water-gas shift reaction thatis the dominant chemical reaction which forms the majorportion of the syngas The energy value analysis showedthat CC contains a manageable amount of energy that canbe converted into useful energy through gasification Thereactive components of CC were mostly oxygen-containingfunctional groups that may play important roles duringgasification The study also established that the thermaldecomposition of CC began at temperatures below 100∘Cwith its complete degradation occurring at temperaturesclose to 1000∘C releasing enormous amount of gases whileSEM analysis revealed compacted vascular bundles and fibertissues linked to carbon-orientation that are among thefeatures of CC that may favour high temperature gasification

The results obtained form a significant basis for thedevelopment of a gasification system that would be tailoredto the demands of the characteristics of CC

Even though the CC used for this study exhibited lowconcentration of metallic elements an elevated weight per-centage of these elements is anticipated when the material isused as feedstock in a gasification process This is becauseof the high amount of ash recorded for CC The weightpercentage of the metallic elements of biomass increases withrising gasification temperature [24] As such further researchis required on reduction of the weight percentage of CCash content This study did not involve the gasification ofCC either via simulation or via experimental investigationof its gasification process This is where challenges could beexperienced with the use of CC It is therefore recommendedthat research be undertaken on the gasification of CC in orderto adequately establish the impact of fuel characteristics ongasification process efficiency The reaction kinetics of thethermal decomposition of CC also require further studies

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

The authors wish to acknowledge the financial support of theNational Research Foundation of South Africa (NRF) theGovanMbeki Research andDevelopment Center (GMRDC)and the Chemistry Department of both the University of FortHare and the Fort Hare Institute of Technology (FHIT) fortheir technical assistance

References

[1] D Gunarathne Optimization of the performance of downdraftbiomass gasifier installed at national engineering research anddevelopment (NERD) Centre of Sri Lanka [Msc thesis] KTHSchool of Industrial Engineering and Management Sweden2012

[2] Extension Farm Energy ldquoCorn cobs for biofuel productionrdquohttparticlesextensionorgpages26619corn-cobs-for-biofuel-production 2016

[3] J T Oladeji and C C Enweremadu ldquoA predictive model for thedetermination of some densification characteristics of corncobbriquettesrdquo inMaterials and Processes for Energy Communicat-ing Current Research and Technological Developments pp 169ndash177 2013

[4] Y Zhang A E Ghaly and B Li ldquoPhysical properties of cornresiduesrdquo American Journal of Biochemistry and Biotechnologyvol 8 no 2 pp 44ndash53 2012

[5] SA Department of Agriculture ldquoMaize productionrdquo httpndaagriczapublications 2016

[6] M Y Suberu A SMokhtar andN Bashir ldquoPotential capabilityof corn cob residue for small power generation in rural NigeriardquoARPN Journal of Engineering and Applied Sciences vol 7 no 8pp 1037ndash1046 2012

[7] L Wang J E Hustad and M Groslashnli ldquoSintering characteristicsand mineral transformation behaviors of corn cob ashesrdquoEnergy and Fuels vol 26 no 9 pp 5905ndash5916 2012

[8] J Lee ldquoBiological conversion of lignocellulosic biomass toethanolrdquo Journal of Biotechnology vol 56 no 1 pp 1ndash24 1997

[9] R N Andre F Pinto C Franco et al ldquoFluidised bed co-gasification of coal and olive oil industry wastesrdquo Fuel vol 84no 12-13 pp 1635ndash1644 2005

[10] J Fermoso Pressure co-gasification of coal and biomass for theproduction of hydrogen University of Oviedo Spain 2009

[11] A Anukam S Mamphweli E Meyer and O Okoh ldquoComputersimulation of the mass and energy balance during gasificationof sugarcane bagasserdquo Journal of Energy vol 2014 Article ID713054 9 pages 2014

[12] A Kumar L Wang Y A Dzenis D D Jones and M AHanna ldquoThermogravimetric characterization of corn stover asgasification and pyrolysis feedstockrdquo Biomass and Bioenergyvol 32 no 5 pp 460ndash467 2008

[13] K Arun and M V Ramanan ldquoExperimental studies on gasifi-cation of corn cob in a fixed bed systemrdquo Journal of Chemicaland Pharmaceutical Research vol 8 pp 667ndash676 2016

[14] A O Aboyade J F Gorgens M Carrier E L Meyer and JH Knoetze ldquoThermogravimetric study of the pyrolysis char-acteristics and kinetics of coal blends with corn and sugarcaneresiduesrdquo Fuel Processing Technology vol 106 pp 310ndash320 2013

[15] S Danje Fast pyrolysis of corn residues for energy production[dissertation thesis] Stellenbosch University 2011

[16] M Danish M Naqvi U Farooq and S Naqvi ldquoCharacteriza-tion of SouthAsian agricultural residues for potential utilisationin future energy mixrdquo Energy Procedia vol 75 pp 2974ndash29802015

[17] J Wannapeera N Worasuwannarak and S PipatmanomoildquoProduct yields and characteristics of rice husk rice straw andcorncob during fast pyrolysis in a drop-tubefixed-bed reactorrdquoSongklanakarin Journal of Science and Technology vol 30 no 3pp 393ndash404 2008

Journal of Chemistry 7

(a) (b)

(c) (d)

Figure 3 SEM images of corn cob obtained at different magnifications

these components releases volatile gases such as CO2and

CH4that are mainly formed due to the decomposition of

hemicellulose between the temperatures of 190 and 320∘CThis degradation temperature for hemicellulose implies lessproduction of tar and char during gasification of CC [24]The third stage of the thermal decomposition process ofCC is indicated by cellulose and lignin degradation between280 and 400∘C for cellulose and between 320 and 450∘C forlignin with total combustion of the sample taking place as itsweight is reduced in the process to give rise to decompositionof hydrocarbons During gasification cellulose and lignindegradation at higher temperatures depict the production ofcarbonized biomass as well as heavy organic and inorganiccompounds [39 40]

37 Microstructural Characteristics of Corn Cob The surfacestructure of CC was examined with a scanning electronmicroscopic instrument that offered detailed informationon imaging and surface composition of the sample Thisprovided a guide as to whether CC is enough carbonaceousmaterial suitable for gasification in a downdraft gasifierFigure 3 shows the SEM images of CC obtained at differ-ent magnifications The images were magnified by a factorof 250 for better understanding and interpretation of themicrostructural characteristics of the material

As can be seen from the images in Figures 3(a)ndash3(d) theshapes are quite irregular and agglomerated The sample is

clearly seen to have no pores even at higher magnificationsan evidence of lack of pretreatment prior to analysis butit exhibits cells on the surface without much characterizedstructure However at 250 magnification (Figure 3(a)) thereseem to be plenty of parallel lines that appear on the surface ofthe sample which look like cells of residual pith that providesa pathway for the transportation of water and nutrients fromthe soil but on increasing magnification to 500 (Figure 3(b))these lines seem to disappear showingmore vascular bundleswith not too conspicuous fragmented cells which indicatesfibrous lignocellulosic nature of CC which is a commonfeature of agricultural biomass residues [24] At higher mag-nification (times750 Figure 3(c)) the vascular bundles are morepronounced with the fragmented cell structures more visibleThepresence of the vascular bundles and cell structures are anindication of carbon-oriented structures which corroboratesthe carbon content data of CC presented in Table 5These cellstructures are also associated with the formation of pathwaysfor the production of gaseous products these features makeCC amenable to high temperature gasification that connotesoptimum efficiency [24 39 41] As image magnification wasincreased to a maximum of 1000 (Figure 3(d)) more featureswere revealed including the size of the vascular bundles andtheir compact nature which are important features used tounderstand the combustion behaviour of biomass materials[42]

8 Journal of Chemistry

4 Conclusions

In order to evaluate CC with regard to its gasification-relatedcharacteristics a detailed assessment based on fuel analysiswas performed The experiments conducted and the resultspresented showed that CC is a biomass feedstock suitablefor gasification due to its low moisture content and due toits low concentration of metallic elements However its highpercentage of ash may create a bit of technical challengesthat may lower gasification efficiency Its low concentrationof nitrogen and sulfur implies reduced emissions of NOXand SO

2during gasification and its hydrogen concentration

is high enough to initiate the water-gas shift reaction thatis the dominant chemical reaction which forms the majorportion of the syngas The energy value analysis showedthat CC contains a manageable amount of energy that canbe converted into useful energy through gasification Thereactive components of CC were mostly oxygen-containingfunctional groups that may play important roles duringgasification The study also established that the thermaldecomposition of CC began at temperatures below 100∘Cwith its complete degradation occurring at temperaturesclose to 1000∘C releasing enormous amount of gases whileSEM analysis revealed compacted vascular bundles and fibertissues linked to carbon-orientation that are among thefeatures of CC that may favour high temperature gasification

The results obtained form a significant basis for thedevelopment of a gasification system that would be tailoredto the demands of the characteristics of CC

Even though the CC used for this study exhibited lowconcentration of metallic elements an elevated weight per-centage of these elements is anticipated when the material isused as feedstock in a gasification process This is becauseof the high amount of ash recorded for CC The weightpercentage of the metallic elements of biomass increases withrising gasification temperature [24] As such further researchis required on reduction of the weight percentage of CCash content This study did not involve the gasification ofCC either via simulation or via experimental investigationof its gasification process This is where challenges could beexperienced with the use of CC It is therefore recommendedthat research be undertaken on the gasification of CC in orderto adequately establish the impact of fuel characteristics ongasification process efficiency The reaction kinetics of thethermal decomposition of CC also require further studies

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

The authors wish to acknowledge the financial support of theNational Research Foundation of South Africa (NRF) theGovanMbeki Research andDevelopment Center (GMRDC)and the Chemistry Department of both the University of FortHare and the Fort Hare Institute of Technology (FHIT) fortheir technical assistance

References

[1] D Gunarathne Optimization of the performance of downdraftbiomass gasifier installed at national engineering research anddevelopment (NERD) Centre of Sri Lanka [Msc thesis] KTHSchool of Industrial Engineering and Management Sweden2012

[2] Extension Farm Energy ldquoCorn cobs for biofuel productionrdquohttparticlesextensionorgpages26619corn-cobs-for-biofuel-production 2016

[3] J T Oladeji and C C Enweremadu ldquoA predictive model for thedetermination of some densification characteristics of corncobbriquettesrdquo inMaterials and Processes for Energy Communicat-ing Current Research and Technological Developments pp 169ndash177 2013

[4] Y Zhang A E Ghaly and B Li ldquoPhysical properties of cornresiduesrdquo American Journal of Biochemistry and Biotechnologyvol 8 no 2 pp 44ndash53 2012

[5] SA Department of Agriculture ldquoMaize productionrdquo httpndaagriczapublications 2016

[6] M Y Suberu A SMokhtar andN Bashir ldquoPotential capabilityof corn cob residue for small power generation in rural NigeriardquoARPN Journal of Engineering and Applied Sciences vol 7 no 8pp 1037ndash1046 2012

[7] L Wang J E Hustad and M Groslashnli ldquoSintering characteristicsand mineral transformation behaviors of corn cob ashesrdquoEnergy and Fuels vol 26 no 9 pp 5905ndash5916 2012

[8] J Lee ldquoBiological conversion of lignocellulosic biomass toethanolrdquo Journal of Biotechnology vol 56 no 1 pp 1ndash24 1997

[9] R N Andre F Pinto C Franco et al ldquoFluidised bed co-gasification of coal and olive oil industry wastesrdquo Fuel vol 84no 12-13 pp 1635ndash1644 2005

[10] J Fermoso Pressure co-gasification of coal and biomass for theproduction of hydrogen University of Oviedo Spain 2009

[11] A Anukam S Mamphweli E Meyer and O Okoh ldquoComputersimulation of the mass and energy balance during gasificationof sugarcane bagasserdquo Journal of Energy vol 2014 Article ID713054 9 pages 2014

[12] A Kumar L Wang Y A Dzenis D D Jones and M AHanna ldquoThermogravimetric characterization of corn stover asgasification and pyrolysis feedstockrdquo Biomass and Bioenergyvol 32 no 5 pp 460ndash467 2008

[13] K Arun and M V Ramanan ldquoExperimental studies on gasifi-cation of corn cob in a fixed bed systemrdquo Journal of Chemicaland Pharmaceutical Research vol 8 pp 667ndash676 2016

[14] A O Aboyade J F Gorgens M Carrier E L Meyer and JH Knoetze ldquoThermogravimetric study of the pyrolysis char-acteristics and kinetics of coal blends with corn and sugarcaneresiduesrdquo Fuel Processing Technology vol 106 pp 310ndash320 2013

[15] S Danje Fast pyrolysis of corn residues for energy production[dissertation thesis] Stellenbosch University 2011

[16] M Danish M Naqvi U Farooq and S Naqvi ldquoCharacteriza-tion of SouthAsian agricultural residues for potential utilisationin future energy mixrdquo Energy Procedia vol 75 pp 2974ndash29802015

[17] J Wannapeera N Worasuwannarak and S PipatmanomoildquoProduct yields and characteristics of rice husk rice straw andcorncob during fast pyrolysis in a drop-tubefixed-bed reactorrdquoSongklanakarin Journal of Science and Technology vol 30 no 3pp 393ndash404 2008

8 Journal of Chemistry

4 Conclusions

In order to evaluate CC with regard to its gasification-relatedcharacteristics a detailed assessment based on fuel analysiswas performed The experiments conducted and the resultspresented showed that CC is a biomass feedstock suitablefor gasification due to its low moisture content and due toits low concentration of metallic elements However its highpercentage of ash may create a bit of technical challengesthat may lower gasification efficiency Its low concentrationof nitrogen and sulfur implies reduced emissions of NOXand SO

2during gasification and its hydrogen concentration

is high enough to initiate the water-gas shift reaction thatis the dominant chemical reaction which forms the majorportion of the syngas The energy value analysis showedthat CC contains a manageable amount of energy that canbe converted into useful energy through gasification Thereactive components of CC were mostly oxygen-containingfunctional groups that may play important roles duringgasification The study also established that the thermaldecomposition of CC began at temperatures below 100∘Cwith its complete degradation occurring at temperaturesclose to 1000∘C releasing enormous amount of gases whileSEM analysis revealed compacted vascular bundles and fibertissues linked to carbon-orientation that are among thefeatures of CC that may favour high temperature gasification

The results obtained form a significant basis for thedevelopment of a gasification system that would be tailoredto the demands of the characteristics of CC

Even though the CC used for this study exhibited lowconcentration of metallic elements an elevated weight per-centage of these elements is anticipated when the material isused as feedstock in a gasification process This is becauseof the high amount of ash recorded for CC The weightpercentage of the metallic elements of biomass increases withrising gasification temperature [24] As such further researchis required on reduction of the weight percentage of CCash content This study did not involve the gasification ofCC either via simulation or via experimental investigationof its gasification process This is where challenges could beexperienced with the use of CC It is therefore recommendedthat research be undertaken on the gasification of CC in orderto adequately establish the impact of fuel characteristics ongasification process efficiency The reaction kinetics of thethermal decomposition of CC also require further studies

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

The authors wish to acknowledge the financial support of theNational Research Foundation of South Africa (NRF) theGovanMbeki Research andDevelopment Center (GMRDC)and the Chemistry Department of both the University of FortHare and the Fort Hare Institute of Technology (FHIT) fortheir technical assistance

References

[1] D Gunarathne Optimization of the performance of downdraftbiomass gasifier installed at national engineering research anddevelopment (NERD) Centre of Sri Lanka [Msc thesis] KTHSchool of Industrial Engineering and Management Sweden2012

[2] Extension Farm Energy ldquoCorn cobs for biofuel productionrdquohttparticlesextensionorgpages26619corn-cobs-for-biofuel-production 2016

[3] J T Oladeji and C C Enweremadu ldquoA predictive model for thedetermination of some densification characteristics of corncobbriquettesrdquo inMaterials and Processes for Energy Communicat-ing Current Research and Technological Developments pp 169ndash177 2013

[4] Y Zhang A E Ghaly and B Li ldquoPhysical properties of cornresiduesrdquo American Journal of Biochemistry and Biotechnologyvol 8 no 2 pp 44ndash53 2012

[5] SA Department of Agriculture ldquoMaize productionrdquo httpndaagriczapublications 2016

[6] M Y Suberu A SMokhtar andN Bashir ldquoPotential capabilityof corn cob residue for small power generation in rural NigeriardquoARPN Journal of Engineering and Applied Sciences vol 7 no 8pp 1037ndash1046 2012

[7] L Wang J E Hustad and M Groslashnli ldquoSintering characteristicsand mineral transformation behaviors of corn cob ashesrdquoEnergy and Fuels vol 26 no 9 pp 5905ndash5916 2012

[8] J Lee ldquoBiological conversion of lignocellulosic biomass toethanolrdquo Journal of Biotechnology vol 56 no 1 pp 1ndash24 1997

[9] R N Andre F Pinto C Franco et al ldquoFluidised bed co-gasification of coal and olive oil industry wastesrdquo Fuel vol 84no 12-13 pp 1635ndash1644 2005

[10] J Fermoso Pressure co-gasification of coal and biomass for theproduction of hydrogen University of Oviedo Spain 2009

[11] A Anukam S Mamphweli E Meyer and O Okoh ldquoComputersimulation of the mass and energy balance during gasificationof sugarcane bagasserdquo Journal of Energy vol 2014 Article ID713054 9 pages 2014

[12] A Kumar L Wang Y A Dzenis D D Jones and M AHanna ldquoThermogravimetric characterization of corn stover asgasification and pyrolysis feedstockrdquo Biomass and Bioenergyvol 32 no 5 pp 460ndash467 2008

[13] K Arun and M V Ramanan ldquoExperimental studies on gasifi-cation of corn cob in a fixed bed systemrdquo Journal of Chemicaland Pharmaceutical Research vol 8 pp 667ndash676 2016

[14] A O Aboyade J F Gorgens M Carrier E L Meyer and JH Knoetze ldquoThermogravimetric study of the pyrolysis char-acteristics and kinetics of coal blends with corn and sugarcaneresiduesrdquo Fuel Processing Technology vol 106 pp 310ndash320 2013

[15] S Danje Fast pyrolysis of corn residues for energy production[dissertation thesis] Stellenbosch University 2011

[16] M Danish M Naqvi U Farooq and S Naqvi ldquoCharacteriza-tion of SouthAsian agricultural residues for potential utilisationin future energy mixrdquo Energy Procedia vol 75 pp 2974ndash29802015

[17] J Wannapeera N Worasuwannarak and S PipatmanomoildquoProduct yields and characteristics of rice husk rice straw andcorncob during fast pyrolysis in a drop-tubefixed-bed reactorrdquoSongklanakarin Journal of Science and Technology vol 30 no 3pp 393ndash404 2008

Journal of Chemistry 9

[18] Leco Corporation Moisture Volatile Matter Ash and FixedCarbonDetermination-Solid Fuel CharacterizationMeasurementsin Coke Organic Application Note Form 203-821-381 LECOCorporation St Joseph Mich USA 2010 httpwwwlecocozawp-contentuploads201202TGA701_COKE_203-821-381pdf

[19] P Tanger J L Field C E Jahn M W DeFoort and J E LeachldquoBiomass for thermochemical conversion targets and chal-lengesrdquo Frontiers in Plant Science vol 4 article 218 2013

[20] ASTM Standards ASTM D 5142-04 Standard Test Method forProximate Analysis of the Analysis Sample of Coal and Cokeby Instrumental Procedures vol 5 ASTM Standards WestConshohocken PA USA 2008

[21] P Elmer 2400 Series II CHNSO Elemental Analysis OrganicElemental Analysis (2016) 2016 httpswwwperkinelmercomlabsolutionsresourcesdocsBRO_2400_SeriesII_CHNSO_Ele-mental_Analysispdf

[22] C Sheng and J L T Azevedo ldquoEstimating the higher heatingvalue of biomass fuels from basic analysis datardquo Biomass ampBioenergy vol 28 no 5 pp 499ndash507 2005

[23] D A Skoog and J J Leary Principles of Instrumental AnalysisChapter 12 Harcourt Brace Jovanovich Philadelphia Philadel-phia PA USA 1992

[24] A Anukam S Mamphweli P Reddy and O Okoh ldquoCharacter-ization and the effect of lignocellulosic biomass value additionon gasification efficiencyrdquo Energy Exploration and Exploitationpp 1ndash16 2016

[25] B M Jenkins Jr and T Miles ldquoCombustion properties ofbiomassrdquo in Fuel Processing Technology T L Baxter Ed vol54 pp 17ndash46 1998

[26] A Abdolali H H Ngo W Guo et al ldquoCharacterization ofa multi-metal binding biosorbent chemical modification anddesorption studiesrdquo Bioresource Technology vol 193 pp 477ndash487 2015

[27] E Gustafsson Characterization of Particulate Matter fromAtmospheric Fluidized Bed Biomass Gasifiers [PhD thesis]Linnaeus University 2011

[28] P McKendry ldquoEnergy production from biomass (part 3)gasification technologiesrdquo Bioresource Technology vol 83 no 1pp 55ndash63 2002

[29] R Fahmi A V Bridgwater I Donnison N Yates and J MJones ldquoThe effect of lignin and inorganic species in biomass onpyrolysis oil yields quality and stabilityrdquo Fuel vol 87 no 7 pp1230ndash1240 2008

[30] J S Brar K Singh J Wang and S Kumar ldquoCo-gasificationof coal biomass A reviewrdquo International Journal of ForestryResearch pp 1ndash10 2012

[31] T Chandrakant ldquoBiomass gasification-technology and utilisa-tionrdquo in Humanity Development Library (2002) 2012 httpwwwpssurvivalcom

[32] T R Miles T R Miles Jr L L Baxter R W Bryers B MJenkins and L L Oden ldquoBoiler deposits from firing biomassfuelsrdquo Biomass and Bioenergy vol 10 no 2-3 pp 125ndash138 1996

[33] D Bostrom N Skoglund A Grimm et al ldquoAsh transformationchemistry during combustion of biomassrdquo Energy and Fuelsvol 26 no 1 pp 85ndash93 2012

[34] B-M Steenari A Lundberg H Pettersson M Wilewska-Bien and D Andersson ldquoInvestigation of ash sintering duringcombustion of agricultural residues and the effect of additivesrdquoEnergy and Fuels vol 23 no 11 pp 5655ndash5662 2009

[35] L Wang G Skjevrak J E Hustad andM G Groslashnli ldquoEffects ofsewage sludge and marble sludge addition on slag characteris-tics during wood waste pellets combustionrdquo Energy and Fuelsvol 25 no 12 pp 5775ndash5785 2011

[36] S Xiong J Burvall H Orberg et al ldquoSlagging characteristicsduring combustion of corn stovers with and without kaolin andcalciterdquo Energy and Fuels vol 22 no 5 pp 3465ndash3470 2008

[37] E Lindstrom M Sandstrom D Bostrom and M OhmanldquoSlagging characteristics during combustion of cereal grainsrich in phosphorusrdquo Energy and Fuels vol 21 no 2 pp 710ndash717 2007

[38] D Chen Z Zheng K Fu Z Zeng J Wang and M LuldquoTorrefaction of biomass stalk and its effect on the yield andquality of pyrolysis productsrdquo Fuel vol 159 article no 9381 pp27ndash32 2015

[39] M Wilk A Magdziarz and I Kalemba ldquoCharacterisation ofrenewable fuelsrsquo torrefaction process with different instrumen-tal techniquesrdquo Energy vol 87 pp 259ndash269 2015

[40] G S Miguel M P Domınguez M Hernandez and F Sanz-Perez ldquoCharacterization and potential applications of solidparticles produced at a biomass gasification plantrdquo Biomass andBioenergy vol 47 pp 134ndash144 2012

[41] S Gaqa S Mamphweli E Meyer and D Katwire ldquoSynergisticevaluation of the biomasscoal blends for co-gasification pur-posesrdquo International Journal of Energy And Environment vol 5pp 251ndash265 2014

[42] A Anukam S Mamphweli P Reddy O Okoh and E MeyerldquoAn investigation into the impact of reaction temperature onvarious parameters during torrefaction of sugarcane bagasserelevant to gasificationrdquo Journal of Chemistry vol 2015 ArticleID 235163 pp 1ndash12 2015

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

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