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Renewable Energy 68 (2014) 414e420Contents lists avaiRenewable Energy

journal homepage: www.elsevier .com/locate/reneneTechnical noteFuel properties of biodiesel produced from selected plant kernel oilsindigenous to Botswana: A comparative analysis

Jerekias Gandure a,*, Clever Ketlogetswe a, Abraham Temub

aUniversity of Botswana, Mechanical Engineering Department, Private Bag 0061, Gaborone, BotswanabUniversity of Dar es Salaam, Chemical and Mining Engineering Department, P. O. Box 35131, Dar es Salaam, Tanzaniaa r t i c l e i n f o

Article history:Received 13 May 2013Accepted 12 February 2014Available online

Keywords:BiodieselFuelPropertiesIndigenous* Corresponding author. Tel.: 267 3554421; fax: E-mail address: gandurej@mopipi.ub.bw (J. Gandu

http://dx.doi.org/10.1016/j.renene.2014.02.0350960-1481/ 2014 Elsevier Ltd. All rights reserved.a b s t r a c t

Fuel characteristics of biodiesel derived from kernel oils of Sclerocarya birrea, Tylosema esculentum,Schiziophyton rautanenii and Jatropha curcas plants were investigated in comparison with petroleumdiesel. The fuel properties under review include flash point, cloud point, kinematic viscosity, density,calorific value, acid value, and free fatty acids. These were determined and discussed in light ofmajor biodiesel standards such as ASTM D 6751 (American Society for Testing and Materials) and EN14214 (European standards). The best biofuel in terms of cold flow properties was S. rautanenii, witha cloud point of 0 C and a pour point of 5 C. The good cold flow properties demonstrate oper-ational viability during the cold season. The heating values of S. birrea and S. rautanenii biodieselfuels were found to be 9.2% and 10.3% lower than that of petroleum diesel while those of T. escu-lentum and J. curcas were both 9.7% lower. Other fuel properties analysed demonstrate that biodieselfuels produced from kernel oils of S. birrea, T. esculentum, S. rautanenii and J. curcas plants haveproperties that are comparable to, and in some cases better than, those of petroleum diesel. Theresults of this study indicate the feasibility of producing quality biodiesel fuel from indigenous seedoils found in Botswana. A balanced allocation of resources however needs to be established toensure that the cultivation of these oil-bearing plants does not compete with the cultivation of foodcrops.

2014 Elsevier Ltd. All rights reserved.1. Introduction

The environmental impact of petroleum fuels, coupled withthe depletion of known petroleum reserves, make renewableenergy sources more attractive and justify the continued searchfor alternative renewable fuels. Biodiesel is among the renewableenergy resources that has attracted considerable attention inrecent times. Biodiesel is highly favoured as alternative topetroleum-based diesel because it is renewable, non-toxic,biodegradable, non-flammable and environmentally friendly[1]. Other strengths of biodiesel fuel include its relatively highheat of combustion (lower but closely comparable to that ofpetroleum diesel), high oxygen value, contributing to combustionefficiency, and minimal contribution to global warming due to itsclosed carbon cycle [2].

Biodiesel fuel is derived from vegetable oils or animal fats [3].The transesterification of an oil or fat with a monohydric alcohol,267 3952309.re).in most cases methanol, yields the corresponding mono-alkylesters, which are defined as biodiesel. Biodiesel has been pro-duced from various sources that include palm oil [4], rapeseed oil[5], soybean oil [6], and sunflower seed oil [7]. Biodiesel has beencharacterized according to its properties that include density,viscosity, heating value, acid value, cetane number, cloud andpour points, and flash point. The viability of biodiesel fromparticular feedstock seed oil depends on such factors as avail-ability of the raw material in commercial quantity, ease of oilextraction, the oil content (yield) of the plant seeds as well astheir product (biodiesel) meeting the basic fuel characteristics fordiesel fuels.

The successful introduction and commercialization of biodieselin many countries around the world has been accompanied by thedevelopment of standards to ensure high product quality and userconfidence. Some of themajor biodiesel standards are ASTMD 6751and the European standard EN 14214.

In the current study, fuel characteristics of biodiesel producedthrough alkali transesterification of three plant oils indigenous toBotswana and J. curcas oil grown under Botswanas natural condi-tions are compared with those of petroleum diesel.

Delta:1_given nameDelta:1_surnameDelta:1_given namemailto:gandurej@mopipi.ub.bwhttp://crossmark.crossref.org/dialog/?doi=10.1016/j.renene.2014.02.035&domain=pdfwww.sciencedirect.com/science/journal/09601481http://www.elsevier.com/locate/renenehttp://dx.doi.org/10.1016/j.renene.2014.02.035http://dx.doi.org/10.1016/j.renene.2014.02.035http://dx.doi.org/10.1016/j.renene.2014.02.035

J. Gandure et al. / Renewable Energy 68 (2014) 414e420 4152. Materials and experimental procedure

2.1. Extraction of plant seed oil

Materials used for experimentation include matured seeds(obtained from ripened fruits) of Sclerocarya birrea, Tylosemaesculentum, Schiziophyton rautanenii and J. curcas plant speciesharvested from Botswanas indigenous woodlands. In order tomaintain oil for experimentation as close to its natural state aspossible, mechanical cold press extraction method was used togenerate crude oil for subsequent analyses. The mechanism for theextractor consists mainly of a piston, a multi-perforated cylindricalstainless steel compression chamber of approximately 0.15 mdiameter and 0.3 m high, and a hydraulic jack system. The sche-matic diagram of the mechanism is shown in Fig. 1.

Eight kilograms (8 kg) of plant seeds were charged into amulti-perforated stainless steel compression chamber, withstainless steel discs placed at intervals of 2 kg of plant seeds.The piston was located to keep the top disc into position. Thehydraulic system was then operated manually to lift up theplatform upon which the multi-perforated stainless steelcompression chamber sits, thereby compressing the seeds andforcing the oil out of the kernel (seed) and through the 1 mmdiameter perforations of the compression chamber. The hydraulicsystem was operated to a maximum pressure of 30 bars to ensuremaximum oil extraction while avoiding over loading the system.The extracted oil was filtered, bottled and kept in a cold roompending conversion to biodiesel as described in Section 2.2.

Solvent extraction was done to establish true kernel oil content(yield) of the four plant species under review, grown under naturalconditions. The process involved seed grinding to fine powder,Soxhlet extraction, filtration, distillation and purging. The solventwas prepared by mixing 300 ml of hexane and 100 ml of iso-propylalcohol in a 500 ml flask. The mixture ensures total extraction of alllipids as hexane extracts all non-polar lipids and iso-propyl alcoholpolar lipids. The separation of solvent from the oil was achievedthrough a distillation process performed using a rotary evaporator.To ensure that no trace of solvent remains in the oil sample, the oilwas purged with nitrogen gas (nitrogen drying) for approximately40 min. Nitrogen is used because it is inert and does not react withoil components.

2.2. Oil characterization

Chemical analysis was performed to establish fatty acid pro-files of the extracted oils to evaluate suitability (quality) for useas feedstock for biodiesel production. The method involvedFig. 1. Schematic of mechanical oil extraction mechanism.analysing standard (reference) samples, generating calibrationcurves for fatty acids identified in the standard samples, andidentifying and quantifying fatty acids present in the extractedoil samples.

To establish the chemical composition of the standard samples,Arachidate was injected into the standard mixtures as an internalstandard (IS) and the samples were run ten (10) times throughthe Gas Chromatograph - Mass Spectrometry (GCeMS) systemat ten (10) concentrations of equal interval from 10 ppm (partsper million) to 1 ppm. At each concentration, peak areas andretention times for all fatty acids present were captured from thechromatogram. Peak area ratios (Analyte/IS) were calculated for allfatty acids present at all concentrations, and these were used togenerate calibration curves for each fatty acid in the standardsamples. The oil samples were also run through the GCeMS systemunder similar conditions and peak area ratios (Analyte/IS) calcu-lated for each fatty acid detected. The instrument used forcomposition analysis is the Waters GCT premier Time of Flight(TOF) mass spectrometer (MS) coupled to the Agilent 6890N gaschromatograph (GC) system. In addition, the National Institute forStandards and Technology (NIST) developed Automated MassSpectral Deconvolution and Identification System (AMDIS) soft-ware package, (chemdata.nist.gov/massspc/amdis) was used forpeak identification. The AMDIS extracts spectra for individualcomponents in a GCeMS data file and identifies target compoundsby matching these spectra against a reference library, in this casethe NIST library.

2.2.1. Gas chromatograph conditionsOne micro litre (1 ml) of oil sample extract was injected into

the system using an auto-injector. The injector temperature wasset at 260 C in the splitless mode. Helium was used as thecarrier gas at a flow rate of 1 ml/min. Separation was achievedusing a 30 m DB5 e MS column. The oven temperature was keptat the initial 100 C for 2 min, and then gradually increased from100 C to 290 C at a rate of 10 C per minute. The total run timewas approximately 35 min.

2.2.2. Mass spectrometer conditionsThe mass spectrometer (MS) conditions that were employed

were a positive polarity of electron ionisation (EI), a source tem-perature of 180 C, and an emission current of 359 mA. Other MSconditions including electron energy and resolutionwere set by thesystems auto tune function. Detection was by the micro channelplate detector (MCP) whose voltage was set at 2700 V. The samplecomposition was identified and quantified using the NIST (2005)mass spectral library using a combination of the Masslynx acqui-sition/data analysis software and the AMDIS by NIST.

The procedure described in Section 2.2 was also used to char-acterize biodiesel samples in order to identify and quantify methylesters present in biodiesel samples.

2.3. Biodiesel preparation

Biodiesel was produced through an alkali catalysed trans-esterification process in the laboratory under strict observationand controlled conditions. One litre of crude plant oil was filteredand pre-heated to approximately 105 C for about 10 min toeliminate water. The oil was allowed to cool to approximately58 C and then charged to a 2 L transparent reactor. A solution ofmethanol of 99.5% purity and 7.5 g of potassium hydroxide pel-lets of 98% purity as catalyst was prepared and mixed until all thepellets had dissolved in methanol, and then charged to the re-action vessel. The molar ratio of methanol to oil was fixed at 1:6,which is optimal ratio for the transesterification of vegetable oils

Table 1Oil yields of studied species and selected conventional vegetable feedstock.

Pant species Yield (wt%) Reference

SB 58.56TE 39.48SR 58.61JC 66.74Jatropha curcas 163.16; 246.27; 350e60 1 [11]; 2 [12]; 3 [13].Soybean 120.00; 218.35; 320.00 1 [14]; 2 [15]; 3 [16].Sunflower 131e35, 239e50 1 [17]; 2 [18].Rapeseed 33e64 [19].Linseed 33.33 [15].Palm 44.60 [15].

SB e Sclerocarya birrea, TE e Tylosema esculentum, SR e Schiziophyton rautanenii, JCe Jatropha curcas.

Table 3Ester composition of biodiesel fuels.

Compound Concentration (mg/ml)

SB100 TE100 SR 100 JC 100

Methyl palmitate (C16:0) 1993.71 1956.89 1521.64 4996.62Methyl Oleate (C18:1) 2294.72 2919.69 2495.47 eMethyl Stearate (C18:0) 1044.37 1415.31 340.69 320.89Methyl Linoleate (C18:2) 560.18 2059.17 1269.49 4596.11Ester content (%) 82.26 89.60 93.70 90.15

SB100 e 100% Sclerocarya birrea biodiesel, E100 e 100% Tylosema esculentum bio-diesel, SR 100 e 100% Schiziophyton rautanenii biodiesel, JC 100 e 100% Jatrophacurcas biodiesel.

Table 4

J. Gandure et al. / Renewable Energy 68 (2014) 414e420416[8,9]. The reactor vessel was tightly closed and contents agitatedusing a mechanical shaker for approximately 1 h at about 58 C.The reactor was then set up-side down and allowed to cool for afurther 3 h. Two distinct layers were formed, the upper layerbeing the methyl ester and the lower layer glycerol (due to itshigher specific gravity). Glycerol was drained off from the bottomof the reactor until only biodiesel (and possibly traces ofunreacted methanol) remained. The biodiesel was then waterwashed twice with 1 L of distilled water per rinse to ensureremoval of all traces of glycerol. A rotary vacuum evaporator wasused to recover the unreacted alcohol from the biodiesel. Theabove procedure was performed for the conversion of S. birrea, T.Esculentum, S. rautanenii and J. curcas seed oils.

The petroleumdiesel used for comparisonwas purchased from alocal Shell petrol Station and had properties including boiling pointof 422 K, vapour pressure of 53 Pa, density of 831 kg/m3, viscosity of2.7 mm2/s at 40 C, acidity of 0.2 mg KOH/g, calorific value of46.5 MJ/kg and cetane number of 48.

2.4. Fuel properties analyses

The fuel characteristics of biodiesel produced from the four oilswere analysed for relative density, viscosity, cloud and pour point,flash point, heat of combustion, and acid value. The viscosity(dynamic) measurements were made according to ASTM stan-dards D445, and were measured using a Fungilab Premium Series(PREL 401024) viscometer coupled to a Thermo Fisher Scientificheating bath circulator. Kinematic viscosity could be approximatedusing the density at 40 C and the dynamic viscosity. The cloudand pour points were determined using the ASTM standard testmethods ASTM D97 and D2500. The ASTM D93 standard testmethod for flash point by PenskyeMartens closed cup tester wasused for the determination of flash points of the diesel fuels. Theheat of combustion of the diesel fuels was determined using theIKA C200 Calorimeter system that has automatic data acquisitionthrough the CalWin calorimeter software which handles calcula-tions for the calorific values of samples. The acidity values of thebiodiesel fuels were measured according to the ASTM D664standard test method [10].Table 2Fatty acid profiles of studied plant oils.

Compound Concentration (mg/ml)

SB TE SR JC

Palmitic acid (C16:0) 0.193 0.264 e 0.122Oleic acid (C18:1) 0.789 e 25.9 eStearic acid (C18:0) 0.136 0.252 18.92 eLinoleic acid (C18:2) e e e 0.6603. Results and discussion

3.1. Results

Oil yields for different plant species, fatty acid profiles of studiedplant oils, ester composition of biodiesel fuels and physicochemicalproperty analyses results are presented in Tables 1e4 respectively,while Figs. 2e7 present comparative fuel properties of the biodieselfuels and petroleum diesel.

3.2. Discussion of results

3.2.1. Oil yield levelsThe oil yield regarded as the actual oil content in this study is the

one determined using solvent extraction method and not press(mechanical) extraction, as the latter is dependent on machine ef-ficiency. After running four Soxhlet extractions for each of theindigenous species, the average oil content was determined as aproportion of total mass. Table 1 compares kernel oil yield levels ofstudied species with those of mostly studied plant species obtainedfrom literature. The results largely indicate that the indigenousspecies have relatively high oil content to warrant good feedstockfor biodiesel production.

3.2.2. Chemical composition of oils and biodiesel fuelsTables 2 and 3 respectively present some of the most common

fatty acids and esters identified in the plant oils and biodiesel fuels,together with their concentrations, while the complete list ofconstituent compounds for S. rautanenii biodiesel is appended as anexample. The composition analyses were performed using a com-bination of AMDIS and Data Analysis Software at a minimummatchfactor of 70%. The peak areas of the compounds were used toestablish the ester content of the biodiesel sample, which werefound to approximately range between 82 and 94%. This ismarginally lower than EN 14214 specification of 96%, while ASTM D6751-02 has no specification for this property. Ester content wascomputed according to equation (1).Results of fuel characteristic analyses of biodiesel and petroleum diesel fuels.

Dieselfuel

Flashpoint(C)

Cloudpoint(C)

Pourpoint(C)

Calorificvalue(MJ/kg)

Acid value(mgKOH/g)

FFA(%)

Density(25 C)(kg/m3)

Kinematicviscosity(40 C)(mm2/s)

SB100 165 2 0 42.2 0.74 0.37 813 3.74TE100 129 8 6 42.0 0.45 0.23 846 3.50SR 100 131 0 5 41.7 0.33 0.17 817 3.86JC100 75 2 2 42.0 0.27 0.14 812 3.47PD 79 2 12 46.5 0.28 0.14 831 2.73

PD e petroleum diesel.

Fig. 2. Flash points of biodiesel fuels and major biodiesel standards.

Fig. 4. Comparison of calorific values of biodiesel and petroleum diesel fuels.

J. Gandure et al. / Renewable Energy 68 (2014) 414e420 417Ester content% Peak areas of all estersPPeak areas of all compounds 100

P

(1)

The ester composition of biodiesel fuels indicates that the mostabundant compounds include methyl palmitate, methyl oleate,methyl stearate and methyl linoleate. These are all long chaincompounds that are largely saturated, with a small degree ofunsaturation. The characteristic ester composition of biodieseldepicted by the mixture of these compounds has a strong influenceon its fuel properties. Fuel properties of plant oil and its derivedbiodiesel improve in quality with increase in carbon chain lengthand decrease as the number of double bonds increase, except forcold flow properties. Thus the cetane number, heat and quality ofcombustion, freezing temperature, viscosity and oxidative stabilityincrease as the chain length increases and decrease as the numberof double bonds increase. A fuel whose constituent mixture ofcompounds is fully saturated will depict higher cetane number andbetter oxidative stability, but poor cold flow properties. The smalldegree of unsaturation depicted by the presence of double bonds incompounds like methyl oleate and methyl linoleate is significant asdouble bonds inhibit crystallization, thus lowering the cloud pointof the fuel. A low cloud point is a desirable fuel property as it en-sures that a fuel remains in the liquid phase at low temperatures.Thus on the basis of composition, biodiesel fuels derived from SB,TE, SR and JC plant species generally depict potential for goodproperties trade-off between cold flow properties, oxidative sta-bility and cetane number.

3.2.3. Fuel properties of biodiesel samplesThe flash point is a fuel property that determines the safety of a

fuel during its handling and storage. It refers to the lowestFig. 3. Cloud and pour points of biodiesel and petroleum diesel fuels.temperature corrected to a barometric pressure of 101.3 kPa(760 mmHg), at which application of spark causes the vapours of aspecimen to ignite under specified conditions of test. This test, inpart, is a measure of residual alcohol in biodiesel that determinesthe flammability classification of the fuel. Table 4 and Fig. 2 showthat the flash points of SB 100, TE 100 and SR 100 are higher thanthat of petroleum diesel. This is largely due to high concentration oflargely saturated esters. This is consistent with the findings ofAhmad et al. [20] and Barua [21] who reported that biodiesel has aflash point that is considerably higher than that of petroleum-baseddiesel. This implies that a lower fire hazard is associated withtransportation, storage and utilisation of biodiesel than with pe-troleum diesel. SB 100 and SR 100 have flash points of 165 C and131 C respectively, which are higher than the ASTM D 93 specifiedminimum of 130 C. T. esculentum (TE 100) is marginally lower thanASTM D 93 specified minimum by 0.8% while JC 100 is significantlylower by 42.3%. The flash points of SB 100, TE 100 and SR 100 arehigher than the EN 14214 specified minimum of 120 C by 37.5%,7.5% and 9.2 respectively. J. curcas (JC 100) and PD have flash pointvalues that are significantly lower than the specified minimum ofboth ASTM D 93 and EN 14214, suggesting that care needs to beexercised during handling, transportation and utilisation processes.Flash points can be improved through blending biodiesel withpetroleum diesel in appropriate proportions.

The cloud point of petroleum diesel was found to be the same asthat of SB 100 and JC 100, while that of SR 100 was lower and that ofTE 100 higher. The difference in value is more significant for TE 100,with a cloud point of 8 C relative to 2 C for petroleumdiesel. All thefour biodiesel fuels have pour points that are higher than that ofpetroleum diesel, with TE 100 recording the highest value of 6 C.Fig. 5. Comparison of acid values of biodiesel and petroleum diesel fuels.

Fig. 6. Comparison of densities of biodiesel and petroleum diesel fuels.

J. Gandure et al. / Renewable Energy 68 (2014) 414e420418These values of cloud and pour points are perceived to be highespecially for application in cold climatic conditions. This is due to ahigh degree of saturation depicted by ester composition of the fuels,which does not sufficiently inhibit crystallization. The pour andcloud point analyses in the characterisation of biodiesel is veryimportant as it determines the suitability of the fuel for large storageand pipeline distribution. Pour point is the lowest temperature atwhich the fuel can still be moved, before it has gelled. Higher pro-portions of saturated fatty acids accounts for higher pour point ofbiodiesel [21]. Cloud point can be defined as the temperature atwhich a cloud of solid crystals first appears (visually observed) in aliquid fuel when it is cooled. It is a conservative measurement of coldflow properties, and most fuels can be used below the cloud pointwithout posing any serious problem. That iswhy the ASTMD 975 hasno specific maximum limit for the cloud point, though it needs to bedetermined for customer specifications [22].

The heat of combustion or calorific value of a fuel is a veryimportant factor in the fuel economy and power deliverability. Theresults presented in Table 4 and Fig. 4 show that the heating valuesof biodiesel fuels produced from the seed oils considered are lowerthan that of petroleum diesel. However, the four biodiesel fuelsconsidered have closely comparable calorific values with a mean of41.98, a range of 0.5, and a standard deviation of 0.2. S. birrea (SB100) has the highest calorific value of 42.2 MJ/kg while SR 100 hasthe lowest value of 41.7 MJ/kg. Generally, the lower heating valuesof biofuels may be linked to relatively higher oxygen content asnoted by Yamane et al. [23] that the presence of oxygen in fuelimproves combustion properties and emissions, but reduces thecalorific value.

Acid value is a direct measure of free fatty acids (FFAs) in thebiodiesel. Free fatty acids are undesirable in the fuel because theyFig. 7. Comparison of viscosities of biodiesel and petroleum diesel fuels.may cause corrosion of the fuel tank and engine components. Theresults from this work, shown in Table 4 and Fig. 5, indicate thatacid values of the four biodiesel and petroleum diesel fuels arewithin specification of ASTM D 6751 standard which specifies amaximum of 0.8 mg KOH/g, and only SB 100 has an acid value thatis above EN 14214 (0.5 mg KOH/g maximum) standard by 48%. Thisimplies that on the ASTM standard, the four biodiesel fuels derivedfrom plant kernel oils indigenous to Botswana can be used in dieselengines with no or minimal risk of acidic attack on engine parts.

Density is an important property of fuel since other perfor-mance characteristics like heating value and viscosity are corre-lated with it [24]. Table 4 and Fig. 6 demonstrate that the density ofbiodiesel fuels produced from indigenous seed oils are lower thanthe density of petroleum diesel except TE 100, with a value of846 kg/m3. The density values recorded for all the four biodieselfuels and petroleum diesel were found to be lower than the EN14214 stipulatedminimum of 860 kg/m3 (range is 860e900 kg/m3).This may be due to the fact that the experimentation carried out inthis work was performed at room temperature while EN 14214stipulates density values at 5 C.

Viscosity is another important property of fuels used in dieselengines. It is a measure of the internal fluid friction of fuel to flowwhich tends to oppose any dynamic change in the fluidmotion, andis themajor reasonwhy straight vegetable oils are transesterified tomethyl esters (or biodiesel). This property influences the injectorlubrication, atomization and combustion processes that take placein the diesel engine. The kinematic viscosity of biodiesel producedfrom the four oils fall within the ASTM (1.9e6.0 mm2/s) standards,with SR 100 having the highest kinematic viscosity of 3.86 mm2/sand JC 100 having the lowest kinematic viscosity of 3.47 mm2/s. Ofall the fuels, petroleum diesel was found to have the lowest kine-matic viscosity value of 2.73 mm2/s. However as seen in Table 4 andFig. 7, SB 100, TE 100 and SR 100 fall within range of EN 14214 (3.5e5.0 mm2/s) standard while JC 100 fall short of the minimumrequirement by 0.86% and PD by 22%. This indicates that the fourbiodiesel fuels can effectively be used in diesel engines since theylargely satisfy the fluidity requirements of alternative biodiesel fuel.

4. Conclusions

The following conclusions can bemade from thework discussedin this manuscript;

1. The results of this work has established that the oil bearingseeds of S. birrea, T. esculentum, S. rautanenii and J. curcas plantsthat are native to Botswana are potential feedstock for theproduction of quality biodiesel since fuel properties of theirderived biodiesel meet major international standards forbiodiesel.

2. Of the four biodiesel fuels, S. rautanenii has the best cold flowproperties. Other fuel properties of the biodiesel fuels arecomparable to those of petroleum diesel.

3. Biodiesel fuels tested met requirements of major internationalbiodiesel standards such as ASTM D 6751 and EN 14214.

4. The abundance of non-arable land for the cultivation of foodcrops in Botswana favours the cultivation of S. birrea, T. escu-lentum, and S. rautanenii which thrive and produce high oilyields under natural conditions. However, care needs to betaken to ensure a balanced allocation of resources in crop pro-duction for both food and fuel purposes to avoid competition.

5. On the basis of environmental advantages of biodiesel coupledwith good fuel properties discussed in this work, individualfarmers, private and public enterprises who depend on diesel topower machinery are encouraged to harvest or cultivate S. bir-rea, T. esculentum, S. rautanenii and J. curcas for the production of

(continued )

Peak# Area Compound name Compoundtype

1,2-Benzenedicarboxylic acid,mono(2-ethylhexyl) ester

42 168,663,070 Tricosanoic acidmethyl ester

Ester

43 105,407,309 Phthalic acid, octyl Ester

J. Gandure et al. / Renewable Energy 68 (2014) 414e420 419biodiesel for their operations. This will minimise dependence onpetroleum diesel.

Appendix 1. Chemical composition of Schiziophytonrautanenii biodiesel at 70% match factor.Peak# Area Compound name Compoundtype

1 33,317,388 Methyl tetradecanoate Ester2 4,406,564,436 7,10-Hexadecadienoic

acid methyl esterEster

3 1,029,911,594 Methyl palmitate Ester4 1,065,552,941 9-Hexadecenoic acid,

methyl esterEster

5 982,100,805 Hexadecanoicacid methyl ester

Ester

6 814,971,460 Decanoic acidmethyl ester

Ester

7 1,321,481,714 1-Pentamine,N-nitro Amine8 1,705,383,089 Pentadecanoic acid

methyl esterEster

9 862,826,992 Heptadecanoic acidmethyl ester

Ester

10 737,592,141 Heneicosanoic acidmethyl ester

Ester

11 3,201,291,912 Octadecanoic acidmethyl ester

Ester

12 15,380,114 Tetradecanoic acidmethyl ester

Ester

13 38,730,304 1,3-dioxirane Oxirane14 13,159,986 Propene-1-amine-N-nitro Alkene-amine16 420,236,759 Isopropyl Linoleate Ester17 636,034,775 Isopropyl linolinate Ester18 540,161,596 10-Decenoic acid

methyl esterEster

19 237,947,389 N-Methylglycine Glycine20 120,309,333 2-Chloroethyl oleate Ester21 184,682,755 9-Octadecenoic acid

methyl esterEster

22 188,126,094 12-Octadecenoic acidmethyl ester

Ester

23 130,320,863 10-Octadecenoic acidmethyl ester

Ester

24 425,088,922 Docosanoic acidmethyl ester

Ester

25 417,107,796 Cyclopropaneoctanoicacid methyl ester

Ester

26 41,726,297 Ethyl 18-nonadecenoate Ester27 84,513,251 5,8,11-Heptadecatrienoic

acid methyl esterEster

28 63,066,887 7,10,13-Eicosatrienoicacid methyl ester

Ester

29 89,189,930 9,12,15-Octadecatrienoicacid methyl ester (Z,Z,Z)

Ester

31 1,820,742,570 Tetracosamethyl-cyclododecasiloxane

Ester

32 867,334,607 2,3-Dimethyl-3-heptene,(Z) Ester33 316,171,389 Nonadecanoic acid

10-methyl esterEster

34 577,000,016 11,13-Eicosanoic acidmethyl ester

Ester

35 314,032,135 Hexanedioic acid,dioctyl ester

Ester

36 614,746,655 Octadecanoic acid,dioctyl ester

Ester

37 683,398,451 Decyl oleate Ester38 2,320,640,803 13-Octadecenoic acid

methyl esterEster

39 500,554,154 8-Octadecenoic acidmethyl ester

Ester

40 947,406,092 15-Tetracosanoic acidmethyl ester

Ester

41 815,490,368 Ester

2-pentyl ester44 113,173,572 Phthalic acid, heptyl

2-pentyl esterEster

45 282,045,496 Hexatriene Alkene46 42,635,261 3-Ethyl-3-methylheptane Alkane47 38,983,882 Vitamin-E Vitamin48 24,753,511 7,10,13-Eicosatrienoic

acid methyl esterEster

49 65,333,001 Oleic acid 3-hydroxypropyl ester Ester50 66,099,219 13-Docosenoic acid methyl ester Ester51 150,945,637 13-Docosanoic acid methyl ester Ester52 21,122,324 Stigma sterol Stigma sterol53 72,213,805 1,2-Benzenedicarboxylic acid,

mono(2-ethylhexyl) esterEster

54 172,799,618 Tricosanoic acid methyl ester Ester55 173,636,637 Tetracosanoic acid methyl-ester Ester56 121,553,263 Pentadecanoic acid methyl ester Ester57 77,384,751 Pentadecanoic acid ethyl-methyl ester Ester58 24,192,692 Tetracosanoic acid ethyl-ester Ester59 388,857,719 Undecasanoic acid methyl ester EsterReferences

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Fuel properties of biodiesel produced from selected plant kernel oils indigenous to Botswana: A comparative analysis1 Introduction2 Materials and experimental procedure2.1 Extraction of plant seed oil2.2 Oil characterization2.2.1 Gas chromatograph conditions2.2.2 Mass spectrometer conditions

2.3 Biodiesel preparation2.4 Fuel properties analyses

3 Results and discussion3.1 Results3.2 Discussion of results3.2.1 Oil yield levels3.2.2 Chemical composition of oils and biodiesel fuels3.2.3 Fuel properties of biodiesel samples

4 ConclusionsAppendix 1 Chemical composition of Schiziophyton rautanenii biodiesel at 70% match factor.References