kinetic and equilibrium studies of the adsorption of cd...

CHAPTER 3

Kinetic and equilibrium studies of the adsorption of Cd (II) from aqueous

solutions by wood apple shell activated carbon

Chapter 3

REMOVAL OF DYES AND HEAVY TOXIC METALS WITH ADSORPTION TECHNIQUE USING LOW COST

ADSORBENTS

113

3.1 INTRODUCTION

With the rapid increase in population and growth of industrialization

worldwide, quality of both surface and ground water is deteriorating day by day.

Industrial uses of metals and other processes have introduced substantial amounts

of potentially toxic heavy metals into the environment [1]. Modern societies use

many goods and amenities involving an increasing range of metallic products.

High consumptions, frequent disposal and replacement of disposable items are

generating diverse types of metallic wastes. These wastes are invariably

discharged into the environment and thus are poisoning the biosphere [2]. Heavy

metals are toxic to aquatic flora, animals and human beings, even at relatively low

concentrations. Some of them (such as, cadmium, mercury, chromium, etc.) are

capable of being assimilated, stored and concentrated by organisms. Cadmium is

introduced into water from smelting, metal plating, cadmium nickel batteries,

phosphate fertilizers, mining, paint, pigments, plastics, stabilizers, alloy industries,

mining, ceramics and sewage sludge etc [3 - 5].

Cadmium is present in air in the form of particles in which cadmium oxide

is probably an important constituent. Cigarette smoking increases cadmium

concentrations inside houses. The average daily exposure from cigarette smoking

(20 cigarettes a day) is 2 to 4 μg of cadmium. Cadmium concentrations in

unpolluted natural waters are usually below 1 μg/dm3. Contamination of drinking-

water may occur as a result of the presence of cadmium as an impurity in the zinc

of galvanized pipes or cadmium-containing solders in fittings, water heaters, water

coolers and taps. Food is the main source of cadmium intake for non-

occupationally exposed people. Crops grown in polluted soil or irrigated with

polluted water may contain increased concentration of Cd(II). Animal kidneys and

livers concentrate cadmium. Levels of Cd(II) concentrations in fruit, meat and

vegetables are usually below 10 μg/kg, in liver 10–100 μg/kg and in kidney 100 –

1000 μg/kg. Cadmium concentrations in tissues increase with age. Both kidney

Chapter 3


ADSORBENTS

114

and liver act as cadmium stores; 50–85% of the body burden is stored in kidney

and liver, 30–60% being stored in the kidney alone [6].

The biological half-life of cadmium in humans is in the range of 10 – 35

years. With chronic oral exposure, kidney appears to be the most sensitive organ.

Cadmium affects the resorption function of the proximal tubules, the first

symptom being an increase in the urinary excretion of low-molecular-weight

proteins, known as tubular proteinuria. The results of studies of chromosomal

aberrations in the peripheral lymphocytes of patients with itai-itai disease exposed

chronically to cadmium via the diet were contradictory. There is some evidence

that cadmium is carcinogenic by the inhalation route, and IARC (1987) has

classified cadmium and cadmium compounds in group 2A. On the assumption of

an absorption rate for dietary cadmium of 5% and a daily excretion rate of 0.005%

of body burden, JECFA (Joint FAO/WHO Expert Committee on Food Additives)

remarked that, if levels of cadmium in the renal cortex are not to exceed 50 mg/kg,

the total intake of cadmium should not exceed 1 μg/kg of body weight per day [6].

The metals cannot be degraded further to non-toxic products or recovered

economically from such a contaminated environment. There are several methods

developed to remove Cd(II) such as ion exchange [7], coagulation [8], flotation

[9], co-precipitation [10], solvent extraction [11], membrane technology [12, 13],

adsorption etc. With increasing environmental awareness and legal constraints

being imposed on discharge of effluents, a need for cost effective alternative

technologies are essential. So amongst all, adsorption process is a promising

technique for the removal of heavy metal ions from waste water, because of its

wide range of target pollutants, high adsorption capacity, possibly selective

adsorbent and hence many researchers have made interest towards the

development of many adsorbents which are being good alternatives for

commercial adsorbents like activated carbon [1]. But commercially available

activated carbon is costly, so there is need to develop economical alternative to

Chapter 3


ADSORBENTS

115

activated carbon. In the present study, wood apple shell activated carbon as

economical and effective adsorbent was developed to get maximum adsorption as

well as used to study the isotherm and kinetic models.

3.2 LITERATURE SURVEY OF ADSORPTION OF Cd(II)

With better awareness of the problems associated with cadmium came an

increase in research studies related to methods of removing cadmium from waste

water, for which a number of technologies have been developed over the years.

The process of adsorption is considered as one of the most suitable methods of the

removal of contaminants from water and a number of low cost adsorbents have

been reported for the removal of heavy metals (ions) from aqueous solutions [14].

Several types of adsorbents are developed to get enhanced adsorption

capacity in inexpensive way. In this invention many researchers have contributed

for development of adsorbents from natural sources, industrial wastes, agricultural

wastes, food waste etc. Amongst various adsorbent the application of riverbed

sand for adsorptive separation of cadmium from aqueous solutions had studied and

0.150 mg/g as adsorption capacity and 56.4% removal of Cd(II) was reported at

298 K [15]. The volcanic rocks, Pumice and Scoria had been used for adsorption

purpose, rock types which are readily available in Ethiopia and other countries,

had 3.84 and 2.24 mg/g adsorption capacity respectively [16]. Local United Arab

Emirates (UEA) sand as a low cost adsorbent was investigated by L. Pappalardo et

al. (2010). The removal efficiency of Cd(II), Cu(II), Pb(II) and Ni(II) from

aqueous solution by white, yellow and red UAE sand at 298 K was found capacity

as with sand yellow > white > red. In case of metal ion Pb(II), Cu(II), Cd(II) and

Ni(II) the removal efficiencies were, respectively 95, 86, 33 and 23% for yellow

sand; 89, 86, 30 and 18% for white sand; and 75, 63, 12 and 13% for red sand,

where results indicated that the removal of Cd(II) was not significant [17]. The

mesoporous silica (SBA-15) has been chemically modified with 2-

Chapter 3


ADSORBENTS

116

mercaptopyrimidine and 3-chloropropyltriethoxysilane prior to immobilization on

the support. The results indicate that under the optimum conditions, the maximum

adsorption value for Cd(II) was 111.3 mg/g, where as the adsorption capacity of

the unmodified mesoporous silica was only 4.50 m/g [18].

Like sand, the various types of local clays are being used anciently. Y. C.

Sharma (2006) had used indigenous clay i.e. china clay as adsorbent and 80.3%

removal at low concentration of metal ion was reported at pH 6.5 [19, 20]. Local

illitic clay, from Jebel Tejra located at South West of Tunisia in North Africa, was

studied for removal of Cr(III) and Cd(II) and found to show 35.70 mg/g and 52.5

mg/g adsorption capacity respectively. In this study it requires 20 h for maximum

adsorption [21]. Brazilian vermiculite was used for the removal of specific toxic

metal as zinc, cadmium, chromium and manganese from aqueous solution.

Amongst all, Cd(II) had been maximum adsorbed to 63.281 mg/g while other

Cr(III), Zn(II), Mn(II) reported as, 39.05, 41.77, 31.53 mg/g [22]. C. N. Haas and

N. D. Horowitz (1986) had determined the chemical conditions which would favor

such binding in the Cd-kaolinite system. Alginic and humic acid, both of which

are sorbable, were found to enhance Cd uptake by kaolinite [23]. Modification of

kaolinite clay mineral with orthophosphate (p-modified sample) enhanced

adsorption of Pb(II) and Cd(II) ions from aqueous solutions of the metal ions. In

binary solution of same, the removal of Cd(II) by orthophosphate modified

kaolinite clay and unmodified kaolinite clay were found to be 14.03 mg/g and 9.23

mg/g respectively [24]. In recent trade, the polymers are emerging and found

successful towards modification of the clay. Kaolinite clay was treated with

polyvinyl alcohol to produce a novel water stable composite called polymer clay

composite adsorbent. This modified adsorbent was found to have a maximum

adsorption capacity for Cd(II) of 1236 mg/g [25].

Loess soils in China have proven to be a potential adsorbent for Cd(II)

removal from waste water. The adsorption capacity of Loess towards Cd(II) has

Chapter 3


ADSORBENTS

117

been reported to be about 9.37 mg/g [26]. The adsorption of heavy metal cations

Pb(II), Cr(III), Cu(II), Cd(II) and Ni(II) from aqueous solution by a mine tailing

which mainly contains muscovite was investigated. The maximum adsorption

capacity (molar basis) followed the order of Cr(III) > Pb(II) > Cu(II) > Ni(II) >

Cd(II). The adsorption capacities for Cd(II) were found to be 3.52 and 8.83 mg/g

at 303 and 323 K respectively [27]. Calcitic limestone was used as more effective

adsorbent for lead but it had very less capacity towards the cadmium. Limestone

solid with 41.0% of calcite was found to be most effective in removing Pb(II) with

a maximum adsorption capacity of 40 mg/g, while maximum cadmium adsorption

capacity was 1.3 mg/g [28]. Jordanian low grade phosphate is suitable adsorbent

for Zn(II) and Cd(II) removal from aqueous solutions in single or binary systems.

It has higher affinity for Zn(II) than that for Cd(II). The Langmuir adsorption

capacity 10.32 mg/g for zinc and 7.54 mg/g for cadmium was reported [29]. The

common minerals or low grade ore waste was used for the Cd(II) removal.

Synthetic goethite prepared by ageing a ferric hydroxide gel at high pH and room

temperature was used and shows the lowest initially adsorbed Cd(II)

approximately 45% [30]. Low grade manganese ore (LMO) of Orissa containing

58.37% SiO2, 25.05% MnO2, 8.8% Al2O3, and 5.03% Fe2O3 as the main

constituents was taken to study its adsorption behaviour for Pb(II), Cd(II) and

Zn(II) from aqueous solutions. Langmuir monolayer adsorption capacities for

Pb(II), Cd(II) and Zn(II) were estimated to be 142.85, 59.17 and 98.0 mg/g of

LMO respectively [31]. The feasibility of using hematite for the removal of Cd(II)

from aqueous solutions was investigated by employing an adsorption technique;

the maximum removal was found to be 98% of the cadmium at 293 K and pH 9.2

after 2 h [32]. Colemanite ore waste (CW) is a waste material that originated from

boron plants. It is primarily composed of fine particles of silica, calcium, boron,

magnesium, iron and potassium oxides. The adsorption capacity of CW was found

to be 33.6 mg/g for Pb(II) and 29.7 mg/g for Cd(II) ions [33].

Chapter 3


ADSORBENTS

118

Amongst the various adsorbents, zeolite is one of the well known

adsorbent, the equilibrium of adsorption of Zn(II), Cd(II) and Pb(II) on regional

low cost natural clinoptilolite containing zeolite tuff (ZEO) and commercial

granulated activated carbon (GAC) was studied. The same metal ion selectivity

series, Pb(II) > Cd(II) > Zn(II), was obtained for both adsorbent and alone Cd(II)

had 5.157 and 17.153 mg/g adsorption capacity by ZEO and GAC respectively

[34].

Chitosan is obtained from the deacetylation of the natural biopolymer

chitin, found in crustaceous shells, insects, and fungal cell walls. For chitosan

maximum adsorption capacity was reported as 557 and 499 mg/g at 1000 mg/dm3

of Pb(II) and Cd(II) metal ions in the solution [35]. Chitosan consists of β-(1,4)-2-

acetamido-2-deoxy-β-D-glucose and β-(1,4)-2-amino-2-deoxy-β-D-glucose units

and contains high contents of amino and hydroxyl groups, which favors the

modification of this biopolymer and the introduction of new functional groups; it

had the adsorption capacity for cadmium 83.75 mg/g [36]. Chitosan was coated

on perlite, and the coated adsorbent was prepared as spherical beads. The

maximum adsorption capacity of chitosan coated perlite beads was determined to

be 178.6 mg/g of bead at 298 K when the Cd(II) concentration was 5000 mg/dm3

at pH 6.0 [37]. Chitosan developed with alumina which reported improvement in

adsorption capacity with increasing in amount of alumina; a maximum recovery of

77% for Cd(II) and 75% for Cr(III) at 30 min was reported [38]. Chitosan

phthalocyanine complex finds applications in heavy metal removal in order of Pb

(98.8%) > Ni (43.6%) > Cd (39.8%) > As (18.0%) and also for adsorption of

several mutagens and carcinogens [39]. Porous beads were prepared by mixing a

chitosan solution in acetic acid and a pectinate solution in water. The obtained

suspension was dropped into a CaCl2 solution. This had 95% removal capacity for

cadmium after 150 min [40].

Chapter 3


ADSORBENTS

119

Many researchers have developed the new adsorbents like polymers,

carbon nanotubes or impregnated the substances with polymer. Novel

nanocomposite adsorbent materials were synthesized by dehydroxylation

condensation of tetraethoxy silane in the presence of guar gum-graft-

polyacrylamide using ammonium hydroxide as catalyst and ethanol as co-solvent.

The maximum adsorption capacity for the composite was found to be significantly

very high i.e. 2000 mg/g [41]. Natural biosorbent like tamarind fruit shell was

polymerized with formaldehyde having sulphonic acid groups and it had 92.988

mg/g Cd(II) ion adsorption capacity [42]. A Cadmium imprinted mercapto

functionalized silica gel adsorbent was synthesized via a surface imprinting

technique for selective adsorbent of Cd(II) ion in aqueous solution. The adsorbent

of Cd(II) ion imprinted ionic polymer (Cd(II)-IIP) has higher capacity and

selectivity than the non imprinted polymer (NIP) adsorbent. Adsorption capacity

of Cd(II)-IIP and NIP adsorbents has 83.89 and 35.91 mg/g respectively [43].

Commercially available resins were utilized to report the good Cd(II) adsorption

capacity. Duolite ES 467 has 13.77mg/g adsorption capacity [44] while, D152

resin [45] and MnO2-loaded D301 [46] shows the 378 and 21.45 mg/g adsorption

capacity respectively.

Carbonaceous nanostructures of different forms, specifically as single and

multiwalled carbon nanotubes are currently considered to be the key elements in

nanotechnology. These are being extensively studied to take advantage of their

properties in numerous fields. The adsorption capacity of nitrogen-doped

multiwalled carbon nanotubes for Cd(II) and Pb(II) was reported 9.33 and 28.80

mg/g respectively [47]. Carbon nanotubes were oxidized with H2O2, KMnO4 and

HNO3; however Cd(II) adsorption capacity was only 1.1 mg/g for carbon

nanotubes, while it reaches 2.6, 5.1 and 11.0 mg/g respectively with oxidized

carbon nanotubes [48]. Surface functionalization of multiwalled carbon nanotubes

by ethylenediamine, via chemical modification of carboxyl groups, using O-(7-

Chapter 3


ADSORBENTS

120

azabenzotriazol-1-yl)-N, N, N’, N’-tetramethyluronium hexafluorophosphate, was

performed with maximum capacity 25.7 mg/g, at 318 K [49].

Fly ash is a waste substance from thermal power plants, steel mills, etc.

and found in abundance all over the world. In recent years, utilization of fly ash

has gained much attention in public and industry, which helps to reduce the

environmental burden and enhance economic benefit. Chemical treatment of fly

ash converts it into a more efficient adsorbent for gas and water cleaning.

Investigations also revealed that unburned carbon component in fly ash plays an

important role in adsorption capacity [50]. The equilibrium adsorption is affected

by the initial pH of the solution and was shown by using bagasse fly ash, which is

a waste material obtained from the flue gas of the bagasse fired boilers of sugar

mills, having adsorption capacity 6.194 mg/g [51]. In another case with same

adsorbent 90% removal of cadmium was reported in about 60 min with 1.24 mg/g

adsorption capacity [52]. Fired coal fly ash, is the residue from lignite combustion

recovered from cyclones and electrostatic filters of the power plant and is

produced worldwide in millions of tones. Fly ash was shaped into pellets with

diameter between 3–8 mm, high relative porosity and very good mechanical

strength which had the adsorption capacities of 20.92 and 18.98 mg/g respectively

for copper and cadmium metal ion [53]. Like fly ash other industrial wastes were

used for the removal of cadmium. The electroplating industry has the metal sludge

as waste which shows 40 mg/g adsorption capacity at 298 K to remove the Cd(II)

metal ion [54]. The manufacture of phosphoric acid by wet process generates the

phosphogypsum, a waste material which shows the good adsorption capacity. The

maximum adsorption capacity of lime preconditioned phosphogypsum was found

to be 131.58 mg/g [55]. Turkish tea waste (fibrous) obtained from various tea-

processing factories was investigated for the removal of Cu(II) and Cd(II) from

single (non-competitive) and binary (competitive) aqueous systems. The

maximum adsorption capacities of Cu(II) and Cd(II) per gram tea waste were

Chapter 3


ADSORBENTS

121

calculated as 8.64±0.51 and 11.29±0.48 mg for single and 6.65±0.31 and

2.59±0.28 mg for binary systems, respectively [56]. Along with waste, the

industrial fungus, Rhizopus cohni, was used as an efficient adsorbent giving the

maximum uptake of cadmium 40.5 mg/g in the optimal conditions [57].

The food waste from food industries or domestic mainly contain the

cellulosic matrix rich of potential metal binding active sites which help to enhance

the adsorption. Areca nut is known since the pre-Christian era and is still very

popular chewing nut in different area of the world. Areca catechu produces the

well-known betel nut of commerce, which is in great demand in eastern countries

for chewing. This when used as adsorbent shows the maximum uptake 1.12 mg/g

for cadmium [58]. The vegetable waste was also reported as adsorbent. Orange

bark, olive cores and olive waste were used as adsorbent which had the adsorption

capacity, 31.01, 12.56 and 6.55 mg/g respectively [59]. Orange peel is one of the

valuable biomass wastes. In world, orange takes up 75% of the total citrus fruits.

Orange waste from the orange juice industry can be considered as a potential

adsorbent. Cadmium uptake is strongly affected by pH, when the pH was

increased from 2 to 6, the percentage of cadmium uptake for a cadmium solution

of 100 mg/dm3 increases from 8 to 98% [60]. Orange peel was washed with 20%

iso-propyl alcohol and alkali saponification had done with NaOH and this material

was modified with oxalic acid which gives 127.01 mg/g adsorption capacity of

Cd(II) ion [61]. In another report the orange waste material was studied for the

effects of alkali saponification, different cross linking temperatures and different

citric acid concentrations on the adsorbent characters and discovered that the

optimum cross linking temperature was 353 K and the optimum citric acid

concentration was 67.44 g/dm3. The maximum cadmium capacity was found to be

101 mg/g in 120 min at pH 6 [62]. The waste pulp of sugar beet remaining from

extraction of sugar was used as adsorbent for Pb(II) and Cd(II) ions. The

Chapter 3


ADSORBENTS

122

maximum metal adsorption capacity of adsorbent was 46.1 mg/g for Cd(II) and

43.5 for Pb(II) ion at 298 K [63].

There are numerous numbers of adsorbents commercially available but

amongst them few are effectively applied and they are expensive so there is need

of developing the alternatives for same. The biosorption of Cd(II) and Zn(II) ions

on to dried Fontinalis antipyretica, a widely spread aquatic moss is reported. The

maximum biosorption capacity of 28.0 mg/g of cadmium was reported which was

independent on temperature. Cadmium uptake was unaffected by the presence of

calcium ions [64]. Dead red macroalga Mastocarpus stellatus was used for

determination of the adsorption of Cd(II) in which isotherms at constant pH

showed uptake values as 55.08 mg/g (at pH 2.4), 62.95 mg/g (at pH 4) and 66.32

mg/g (at pH 6) [65]. Another red alga Ceramium virgatum was reported with 39.7

mg/g adsorption capacity [66]. Cadmium (II) adsorption properties of pre-treated

biomass of marine alga Durvillaea potatorum were investigated. At pH 5, the

maximum adsorption capacity of Cd(II) of the pre-treated biomass was 123.64

mg/g [67]. Biosorption of Cd(II) ions from aqueous solution onto immobilized

cells of Pycnoporus sanguineus was investigated in a batch system. The results

showed that biosorption of Cd(II) ions was spontaneous and of endothermic nature

and with 3.18 mg/g adsorption capacity [68].

Sheep manure waste (SMW) had been shown to be very efficient in

removing nickel and cadmium from dilute aqueous solutions which shows the

relatively higher affinity for cadmium binding than that for nickel. The removal of

cadmium was up to 71% when Cd(II) concentration was 100 ppm and SMW

adsorbent 8 mg/dm3 [69]. Crayfish carapace was applied to remove divalent heavy

metal ions Cu, Cd, Zn and Pb from wastewater where recorded maximum uptakes

are of 200, 217.39, 80, and 322.58 mg/g for Cu, Cd, Zn, and Pb, respectively [70].

Cadmium, lead and nickel from industrial waste waters have been separated by

using tea waste as a natural adsorbent. The removal efficiency was highest for lead

Chapter 3


ADSORBENTS

123

and was less for cadmium. The removal efficiency was found to be 100% for lead,

for nickel 85.7 and 77.2% for cadmium [71]. Along with this, brewer’s yeast was

used as adsorbent for the removal of Ni(II) and Cd(II) metal ions from aqueous

solution. Maximum uptakes of Ni(II) and Cd(II) by brewer’s yeast were estimated

to be 5.34 and 10.17 mg/g, respectively [72].

The agro wastes are abundantly available all over which introduced a new

application as an adsorbent in recent years by many researchers. The feasibility of

using various agricultural residues viz. sugarcane bagasse (SCB), maize corncob

(MCC) and Jatropha oil cake (JOC) for the removal of Cd(II) from aqueous

solution is checked. The maximum adsorption of cadmium (II) metal ions was

observed at pH 6 for all the adsorbents viz. 99.5, 99 and 85% for JOC, MCC and

SCB respectively [73]. Grape bagasse as an alternative natural adsorbent to

remove Cd(II) and Pb(II) ions from laboratory effluent was developed. The

Langmuir model shows adsorption to be 86.99 and 88.68 mg/g for Cd(II) and

Pb(II) respectively [74]. Coconut copra meal, a waste product of coconut oil

production used as adsorbent for biosorption of cadmium ions from solution,

which was spontaneous and exothermic process. The saturated monolayer

biosorption capacity of the copra meal for cadmium ions at 299K was calculated

to be 4.92 mg/g [75]. Husk of Lathyrus sativus was used as adsorbent which had

the very fast process and more than 90% of the total adsorption took place within

the first 5 min having final maximum adsorption capacity 35 mg/g [76]. Corncob

is plentifully available agro waste; it is used as it is natural and had 0.0772 mmol/g

adsorption capacity [77]. The modifications were carried out in corncob to

improve the capacity and the Cd(II) ions were adsorbed mainly at the carboxylic

sites. The adsorption capacity is directly proportionally to the concentration of

carboxylic sites in the corncob. The adsorption capacity of natural corncob was

increased to 10.8 and 3.8 times when the corncob was oxidized with citric acid and

nitric acid respectively. The adsorption capacity of natural corncob was 4.73 mg/g

Chapter 3


ADSORBENTS

124

and that of oxidized with 0.6 M citric acid and 1M nitric acid 52.1 mg/g 19.3 mg/g

was observed respectively [78]. The corn stalk modified using graft

copolymerization to produce absorbent and raw corn stalk showed the 22.17 and

3.81 mg/g adsorption capacity respectively [79].

The leaves of olive tree (Olea europaea) were used as adsorbent by three

methods and they had monolayer adsorption capacity as 42.19, 55.87 and 64.94

mg/g for the conventional method, the ultrasound assisted method and the

combined method, respectively [80]. Olive cake is a waste of olive factory and

usually used as fertilizer and as feeding material. Its structure contains organic

compounds like lignocellulosic material, polyphenols and also amino acid, protein,

oil, and tannins. It is used as adsorbent and Langmuir adsorption capacity was

found to be 10.560 mg/g and Freundlich adsorption capacity 0.196 mg/g at 308 K

and pH 4.50 [81]. The use of natural adsorbent such as olive cake to replace

expensive imported synthetic adsorbent is particularly appropriate for developing

countries. Cadmium ions from its aqueous solution using olive cake as adsorbent

shown that with an increase in temperature from 301 to 318 K, the adsorption

capacity is decreased from 65.4 to 44.4 mg/g [82]. The removal characteristics of

cadmium and nickel ions from aqueous solution by exhausted olive cake ash were

studied. The estimated maximum capacities of nickel and cadmium ions adsorbed

were 8.38 and 7.32 mg/g, respectively [83]. An agricultural solid by-product olive

stone was converted to activated carbon with 20% ZnCl2 solution and was found

to be the best sample of the produced activated carbons from olive stone with the

specific surface area of 790.25 m2/g and has 1.851 mg/g adsorption capacity at

293K [84].

Rice husk as well its modified conversions or activated carbon were used

as adsorbents. In case of rice husk the maximum adsorption reported was 98.65%

with 21.28 mg/g adsorption capacity [85]. Some simple and low-cost chemical

modifications resulted in increasing the adsorption capacity of raw rice husk

Chapter 3


ADSORBENTS

125

(RRH) from 8.58 mg/g to 11.12, 20.24, 16.18 mg/g and reducing the equilibrium

time from 10 h of RRH to 2, 4 and 1 h for epichlorohydrin treated rice husk,

NaOH treated rice husk, sodium bicarbonate treated rice husk respectively [86].

Low cost rice husk ash shows maximum metal ions removal of 35.3% for Zn(II),

27.8% for Ni(II) and 23.3% for Cd(II) at initial concentration of 500 mg/dm3 at 10

kg/m3 adsorbent dosage [87]. Novel bio-adsorbent wheat bran has been

successfully utilized for the removal of Cd(II) from wastewater. The maximum

removal of Cd(II) was found to be 87.15% at pH 8.6, at initial Cd(II)

concentration of 12.5 mg/dm3 with 0.703 mg/g adsorption capacity [88]. In one

another case wheat bran was used without any treatment and 15.71 mg/g

adsorption capacity was reported [89]. By using sulphuric acid as impregnating

agent for wheat bran the cadmium adsorption capacity was increased from 43.1

mg/g to 101 mg/g [90].

Various biomasses were used as adsorbent like, juniper wood and bark was

applied to adsorb cadmium. The pseudo second order had given the equilibrium

adsorption capacity of Cd(II) 10.30 mg/g for juniper bark and 3.18 mg/g for

juniper wood [91]. Using maize tassel as an alternative adsorbent for the removal

of Cr(VI) and Cd(II) ions from aqueous solutions, an adsorption capacity of 79.1%

for Cr(VI) at pH 2, exposure time of 1h at 298 K and maximum adsorption

capacity of Cd(II) of 88% was obtained in the pH range of 5-6 at 298 K after

exposure time of 1 h [92]. Castor (Ricinus communis) seed hull is an agricultural

residue obtained during processing of castor seeds before oil extraction. It is high

in fiber content that is expected to provide ample negatively charged sites for

capturing positively charged species which explored 6.983 mg/g as adsorption

capacity at pH 5.8 [93]. The biosorption capability of Ulmus leaves and their ash

for Cd(II) ions removal from wastewaters has been investigated which was found

to be rapid and reached to 92% of equilibrium capacity in 60 minutes [94]. A

biosorbent, neem leaf powder (NLP), was prepared from the mature leaves of the

Chapter 3


ADSORBENTS

126

Azadirachta indica (neem) tree. Adsorption increases from 8.8% at pH 4.0 to

70.0% at pH 7.0 and 93.6% at pH 9.5. The Langmuir monolayer adsorption

capacity for Cd(II) of NLP was 158 mg/g reported from aqueous solution [95]. In

another case the Cd(II) was removed by neem saw dust which has 26.73 mg/g and

neem bark has 25.57 mg/g adsorption capacity respectively [96]. Tree sawdust of

walnut in Turkey is explored for the removal of toxic heavy metal ions such as

Pb(ll), Cd(1I) and Ni(II) from aqueous solutions, amongst them Cd(II) was

adsorbed to 5.76, 5.69, 5.70 mg/g with respect at 298, 318, 333 K temperature

respectively [97].

Extensive research has been carried out during the past few years to find

low cost and high capacity adsorbents for the removal of metal ions. A wide range

of adsorbents have been developed and tested, including several activated carbons

such as, bone char which has high adsorption capacities for cadmium, copper and

zinc ions, namely 53.62, 45.06 and 33.01 mg/g respectively [98]. The jackfruit

peels, an agricultural waste from food processing industry, after carbonization can

be employed for the economical removal of Cd(II) from aqueous solution. With

increase in Cd(II) concentration from 20 to 40 mg/dm3, the amount of Cd(II)

adsorbed increased from 28.3 to 50.6 mg/g at equilibrium time [99]. In another

report the jack fruit seed carbon (JFSC) was compared with the commercial

activated carbon (CAC) which concluded that, Cd(II) was found to adsorb strongly

on the surface of both commercial activated carbon and jack fruit seed. JFSC

possess 1.215 mg/g and CAC had 0.695 mg/g as adsorption capacity, hence it is an

effective adsorbent for the removal of Cd(II) [100]. The walnut (Juglans regia L.),

hazelnut (Corylus avellana), pistachio (Pistaca), almond (Amygdolus) shells and

apricot (Armeniaca bulgar) stone precursor were found to be good raw materials

for developing activated carbons. Cd(II) was removed by walnut, hazelnut,

almond and apricot as 50.9, 90.5, 74.8 and 86.0% respectively while pistachio had

shown only 33.8% removal [101].

Chapter 3


ADSORBENTS

127

Ceiba pentandra tree is widely distributed in the deciduous forests of

western and eastern India especially in hotter areas. The plant parts, root, bark,

gum and leaf have high medicinal applications except hulls. Activated carbon

prepared from Ceiba pentandra hulls, an agricultural solid waste by-product was

used for removal of copper and cadmium and adsorption capacity was found to be

20.8 and 19.5 mg/g, respectively [102]. Another waste, bean husk (Phaseolus

vulgaris) was developed into activated carbon at 643 K in Argon (Ar), followed by

chemical activation using HNO3. The maximum uptake of Cd(II) was 11, 60 and

180 mg/g for commercial carbon, bean husk carbon and activated carbon,

respectively [103]. Bamboo charcoal was produced from the rapidly growing

moso bamboo plants, which had the maximum adsorption capacity of 12.08 mg/g

[104]. Cashew nut shells were converted into activated carbon powders using

KOH activation plus CO2 gasification at 1027 K. The adsorption capacity of

activated carbon prepared from cashew nut shells for Pb(II) and Cd(II) ions was

reported 28.90 and 14.29 mg/g respectively [105]. Apricot stones were carbonized

and activated after treatment with sulphuric acid (1:1) at 473 K having ability to

adsorb metal ions were obtained in the descending order of Cr(VI) > Cd(II) >

Co(II) > Cr(III) > Ni(II) > Cu(II) > Pb(II). Highest adsorption occurred at pH 1–2

for Cr(VI) and at pH 3–6 for the rest of the metal ions, respectively. In case of

Cd(II), as the pH was increased from 1 to 6 the capacity was also increased from

3.08 to 3.57 mg/g [106]. Recently a new form of activated carbon has appeared:

carbon aerogel, which has the maximum adsorption capacity of 15.53 mg/g of

Cd(II) [107].

The adsorption technique is the effective and economical to application

level. The regular commercial activated carbon is expensive, so there is a need of

alternatives for same. In present study, wood apple (Limonia acidissima) shell

activated carbon has developed as an adsorbent. The activated carbon developed

by using impregnating agent which has helped to make the porous which is

Chapter 3


ADSORBENTS

128

responsible for the more adsorption capacity of metal ion. In present study, well

known isotherms are applied, while kinetic study was carried out using two

models. The thermodynamic study was carried for Cd(II) adsorption on Wood

Apple Shell Activated Carbon (WASAC).

The wood apple has medicinal uses as well as it is used in making sweet in

Kolhapur and Belgaum District (India). Wood apple shell is unemployed easily

and abundantly available which could be applied as current need of humankind to

remove heavy metal pollutants as its application. It helps to remove Cd(II) very

effectively and economical.

3.3 EXPERIMENTAL

3.3.1 Preparation of materials and characterization of adsorbent

Sample of Limonia acidissima (wood apple) shell was collected from local

market. The procedure of preparation of material was followed as that reported in

Chapter 2 (2.3.1). The stock solution of Cd(II) 1g/dm3 was prepared from

CdSO4.8H2O. By using this stock solution the desired dilutions were made and

used throughout the study.

The developed adsorbent was characterized as discussed in chapter 2 (2.3.2).

3.3.2 Batch adsorption experiment

Batch mode adsorption studies were carried out with 400 mg of adsorbent

and 50 mL of Cd(II) solution of desired concentrations at an initial pH of 6.5 in

250 mL Erlenmeyer flasks and agitated at 150 rpm for predetermined time

intervals at constant temperature on an orbital shaker. The concentration of free

Cd metal ion in the effluent was determined with atomic adsorption spectroscopy

(A Analyzer 300).

Adsorption isotherm study was done with varying the concentration

of Cd(II) from 100 to 420 mg/dm3 at 299 ± 2 K, pH 6.5 and time of contact 4h at

Chapter 3


ADSORBENTS

129

150 rpm in the Erlenmeyer flasks. For the thermodynamic study, temperature was

varied from 303 K to 323 K. The equilibrium adsorption capacity of WASAC was

evaluated using the equation, which is given in chapter 2 (2.3.3).

3.4 RESULT AND DISCUSSION 3.4.1 Effect of pH

The effect of pH on adsorption of Cd(II) was studied with varying the pH

from 1to 9. The concentration of Cd(II) was taken to be 100 mg/dm3 while the

volume of solution was kept to 50 mL, at constant temperature 299 ± 2 K and it

was agitated for 4 h at 150 rpm. From Fig. 3.1, (Table 3.1) it clearly indicates that,

the adsorption was significant above pH 6. For the further study pH 6.5 was

confirmed because, above neutral pH the reaction mixture forms precipitate. The

cadmium percentage removal and adsorption capacity was found to be 98.80% and

12.35 mg/g respectively for WASAC.

The pH of the solution was found to have a great effect on the adsorption

of Cd(II) ions. The adsorption increased sharply in the pH range 3 to 5 attaining

almost a constant value at higher pH. Such results could be attributed on the basis

of the change in the carbon surface charge with change in pH of the solution [108].

The lower adsorption capacity observed at low pH may be explained on

the basis on electrostatic repulsive forces between positively charged H3O+ and

Cd(II) ions. At low pH values, the concentration of H3O+ is higher than that of

Cd(II) ions and, hence, these ions are adsorbed on the active sites of activated

adsorbents, leaving Cd(II) ions free in the solution. When the pH was increased,

Cd(II) ions would replace with H3O+ ions. Competing effect of H3O

+ decreased

with increase of the pH, which increases the adsorption yield of the Cd(II) ions.

The adsorption capacity increases with increase in pH value up to 6 and remains

constant up to pH 9.0 but we have considered range of pH 6 - 7; as the removal

takes place by adsorption as well as precipitation of Cd(II) ions in the form of

Chapter 3


ADSORBENTS

130

Cd(OH)2. The decrease in adsorption yield at alkaline conditions can be attributed

to the formation of Cd(OH)3− ions taking place as a result of dissolution of

Cd(OH)2 due to its amphoter characteristic. The hydrolysis and precipitation of

metal ions affect adsorption by changing the concentration and form of soluble

metal species those are available for adsorption. The hydrolysis of Cd(II) ions may

be represented by following reaction,

Cd2+ + 2nH2O ↔ Cd(OH)n2−n +nH3O+ (1)

Depending upon the pH of the solution, various species of cadmium can be formed

during the hydrolysis. The hydrolysis extent of Cd(II) ions is unimportant up to

approximately pH 7.5 and cadmium is in the form of Cd2+ ions at this pH. For that

reason it can be said that the adsorption mechanisms can be explained on the basis

of H3O+–Cd2+ exchange reaction [90].

Initial pH of solution was varied within the range 1 – 7. This pH range was

chosen in order to avoid metal hydroxide precipitation. The metal hydroxide

precipitation was observed from pH 7.5 [109]. The effect of initial pH of solution

on the sorption dynamics for cadmium onto WASAC is shown in Fig. 3.1 (Table

3.1). It was observed from the results, negligible precipitations occurred at

pH<8.0, but at higher pH (namely pH 12) more precipitation occurred, and the

initial concentration (C0 = 100 mg/dm3) decreased to 89.4 mg/dm3.

3.4.2 Effect of time

It’s very normal observation among all adsorption studies that, as per the

increase in the contact time there is enhancement in the adsorption of adsorbate in

both cases in percentage as well as amount adsorbed. This is probably due to a

larger surface area of the WASAC being available at the beginning for the

adsorption of cadmium. As the surface adsorption sites become exhausted, the

Chapter 3


ADSORBENTS

131

uptake rate is controlled by the rate at which the adsorbate is transported from the

exterior to the interior sites of the adsorbent particles. Present experiments were

done at the constant temperature. The cadmium metal ion concentration was 100

mg/dm3 while, other remaining conditions pH, rpm etc. were constant. Effect of

shaking period was done at various time intervals from 30 min to 360 min. The

increase in percentage adsorption from 31.78% to 98.80% (Table 3.2, Fig. 3.2)

was observed up to 220 min. After that, there was no any significant change

observed. So, for further study the 240 min was fixed as contact time.

3.4.3 Effect of initial concentration of Cd(II)

The effect of initial cadmium concentration in the range of 100 to 420

mg/dm3 on adsorption was investigated (Fig. 3.3). Along with pH all parameters

were kept constant in this study. It is evident from the Fig. 3.3 that, as the

concentration of Cd(II) was increased, the amount adsorbed was increased but,

there was decrease in percentage removal. It is because, the initial cadmium

concentration provides the necessary driving force to overcome the resistances to

the mass transfer of cadmium between the aqueous phase and the solid phase. The

increase in initial cadmium concentration also enhances the interaction between

cadmium and WASAC i.e. adsorbent. Therefore, an increase in initial

concentration of cadmium enhances the adsorption uptake of cadmium and results

in higher adsorption, while the adsorption was carried out for fixed number of

active sites, there was decrease in percentage removal of Cd(II). The amount

adsorbed of Cd(II) was increased from 12.35 to 27.64 mg/g (Table 3.3) as the

initial metal ion concentration increased.

3.4.4 Effect of adsorbent dosage

Adsorption dosage is one of the vital parameter in the study. The adsorbent

dosage i.e. WASAC was varied from 50 − 400 mg/dm3, to study the effect on the

Chapter 3


ADSORBENTS

132

adsorption of Cd(II). To study this effect, the concentration of Cd(II) was taken as

100 mg/dm3 and other parameters were kept constant. As the amount of adsorbent

was increased, the amount adsorbed and percentage removal of Cd(II) was

respectively increased. The adsorbent dosage affects directly on the adsorption

capacity, as there is increase in dosage more active sites becomes available for

adsorbate and it was confirmed from the Fig. 3.4 and Table 3.4. The maximum

amount of 12.35 mg/g of Cd(II) was adsorbed for 400 mg of WASAC and 98.80%

removal of Cd(II) was found, so throughout the study the 400 mg/dm3 amount of

WASAC as adsorbent was kept constant.

3.4.5 Effect of agitation speed

The agitation speed effect on the adsorption amount and percentage

removal has investigated. To study this parameter, rpm was varied from 50-200

rpm. For this experiment, the period of agitation was 4 h and temperature was 299

± 2 K with remaining all optimum conditions kept constant. In present study, it

was observed that, the interaction between adsorbate and adsorbent was effective

at high speed i.e. 150 rpm and more up to 200 rpm. It is very clear from the Fig.

3.5 (Table 3.5) that, there was increase in adsorption with respect to rpm and

above 150 rpm no any significant change was observed. So the rpm was fixed at

150 for the further study.

3.4.6 Adsorption isotherm

Adsorption equilibrium isotherms are basic requirements for designing any

adsorption system. The adsorption isotherm indicates how the adsorbate

distributes between the liquid phase and the solid phase when the adsorption

process reaches an equilibrium state. Fig. 3.6 (Table 3.6) presents the plot of

amount of cadmium adsorbed against its concentration in aqueous phase at

equilibrium. Isotherm data obtained with a range of initial cadmium concentration

Chapter 3


ADSORBENTS

133

showed an increase in the amount of cadmium adsorbed when the initial metal

concentration was raised from 100 to 420 mg/dm3. The shape of the curves clearly

indicated that the isotherms for all temperatures belong to L-type according to the

classification of equilibrium isotherm in solution [89].

Adsorption isotherms express the mathematical relationship between the

quantity of adsorbate and equilibrium concentration of adsorbate remaining in the

solution at a constant temperature. The adsorption data has been analyzed with,

Langmuir and Freundlich isotherm models.

3.4.7 Langmuir isotherm

Langmuir isotherm model is based on assumption that a saturated

monolayer of adsorbate molecules is present on the adsorbent surface, the

adsorption energy is constant and there is no migration of adsorbate molecules in

the surface plane when maximum adsorption capacity occurs. The Langmuir

equation is as given in chapter 2 (2.4.7).

A plot of Ce/qe versus Ce (Fig. 3.7, Table 3.7) indicates a straight line of

slope 1/qm and an intercept of 1/KLqm. A further analysis of the Langmuir equation

can be made on the basis of a dimensionless equilibrium parameter, RL also known

as the separation factor, as discussed in chapter 2 (2.4.7).

The Langmuir constants (qm and KL) are calculated from the plots (Fig.

3.7) and are presented in Table 3.8. The data related to the equilibrium obeyed

well the Langmuir models. The maximum adsorption capacity of adsorption of

Cd(II) by Langmuir isotherm was 28.33 mg/g which is more agreed to calculated

value 27.64 mg/g (Table 3.8). The value of was RL subsist in between 0.049 to

0.896 which indicates the favour of adsorption i.e. formation of monolayer of

Cd(II) ions on the surface of WASAC.

Chapter 3


ADSORBENTS

134

3.4.8 Freundlich isotherm

The Freundlich isotherm model is the empirical relationship and is based

on an assumption that the adsorption energy of a metal ion binding to a site of an

adsorbent depends on whether the adjacent sites are already occupied or not. The

experiments were carried out when the agitating period was 4 h and temperature

was 299 ± 2 K with remaining parameters kept steady. The Freundlich equation

used is as given in chapter 2 (2.4.8). The plot the log qe vs. log Ce (Fig. 3.8, Table

3.9) gives a linear trace with a slope of 1/n and intercept of log Kf. The Kf is the

measure of adsorption capacity and n is the adsorption intensity which is given in

table 3.10. The Freundlich adsorption capacity by this plot is 11.280 mg/g and

regression factor (R2) was 0.953.

From the results it was clearly observed that both models were well suited

for adsorption of Cd(II) on WASAC, but the regression factor as well as the

calculated and experimental values correlates more correctly with the Langmuir

values; on this basis it could be concluded that, Cd(II) ion form monolayer on

surface of WASAC and the adsorption was chemisorption.

3.4.9 Adsorption kinetics

The study of adsorption kinetics describes the solute uptake rate and

evidently these rate controls the residence time of adsorbate uptake at the solid–

solution interface including the diffusion process [96]. The kinetic study for the

adsorption of Cd(II) was conducted at optimum pH 6.5, where maximum

adsorption takes place. The adsorption study was tested for two models i.e. pseudo

first and pseudo second order model. The experiments were carried out for time

intervals varied from the 0 to 240 min at constant temperature, with 100 mg/dm3

concentration of Cd(II) by keeping other parameters constant. The pseudo first

order was studied with Lagergren equation, as discussed in chapter 2 (2.4.9). Plot

Chapter 3


ADSORBENTS

135

of log (qe − qt) vs. t (Fig. 3.9, Table 3.11) gives a straight line for first order

adsorption kinetics, which allow computation of the adsorption rate constant k1.

For pseudo-second order rate equation was used as discussed chapter 2

(2.4.9). The rate parameters k2 and qe can be directly obtained from the intercept

and slope of the plot of t/qt vs. t (Fig. 3.10, Table 3.12). For pseudo first order and

pseudo second order model the equilibrium adsorption capacity was 13.652 and

17.762 mg/g respectively. The calculated equilibrium adsorption capacity was

12.35 mg/g. The rate constant and other results obtained graphically for both

adsorption models are listed in Table 3.13. The calculated and experimental results

reveal that, the pseudo-first order model provided a better approximation to the

experimental kinetic data than the pseudo-second order model for adsorption of

Cd(II) ion from aqueous solution.

3.4.10 Intraparticle diffusion study

There are essentially three consecutive mass transport steps associated with

the adsorption of solute from the solution by an adsorbent. These are (i) film

diffusion, (ii) intraparticle or pore diffusion, and (iii) sorption into interior sites.

The third step is very rapid and hence film and pore transports are the major steps

controlling the rate of adsorption. In order to understand the diffusion mechanism,

kinetic data was further analyzed using the intraparticle diffusion model based on

the theory proposed by Weber and Morris [54]. The amount of cadmium adsorbed

(qt) at time (t), was plotted against (t1/2), from the intraparticle diffusion equation,

(which is discussed in chapter 2 (2.4.10)) and the resulting plot is shown in Fig.

3.11 (Table 3.14). In present experiment, concentration of Cd(II) was 100 mg/dm3

and all other conditions were kept constant including temperature. The rate

constants of intraparticle diffusion are given in Table 3.15. The intraparticle

diffusion process is controlled by the diffusion of ions within the adsorbent.

Chapter 3


ADSORBENTS

136

3.4.11 Adsorption thermodynamics

As the theory of adsorption gives the general information about the

influence of temperature on the adsorption, the study of adsorption

thermodynamic is essential. We have used 420 mg/dm3 Cd(II) ion concentration to

study the adsorption on 400 mg WASAC and agitation was done for 4h at 150

rpm. The adsorption was increased with increase in temperature from 303 to 323

K with 5 K (Fig. 3.12, Table 3.16). This indicates that the adsorption reaction was

endothermic in nature. The enhancement in the adsorption capacity may be due to

the chemical interaction between adsorbate and adsorbent, creation of some new

adsorption sites or the increased rate of intraparticle diffusion of Cd(II) ions into

the pores of the adsorbent at higher temperatures.

For the above condition, the standard Gibb’s energy (∆G○), standard

enthalpy (∆H○) and standard entropy (∆S○) were calculated from well known

standard Gibb’s energy and Van’t Hoff’s equations which as given in chapter 2

(2.4.11). The ∆H○ and ∆S○ were obtained from the slope and intercept of Van’t

Hoff’s plot of lnKc versus 1/T (Fig. 3.13, Table 3.17). The positive value of ΔH○

indicates that the adsorption process is endothermic. The negative values of ΔG○

reflect the feasibility of the process and the values become more negative with

increase in temperature. Standard entropy determines the disorderliness of the

adsorption at solid–liquid interface, Table 3.19 summarizes the results. The

positive value of ΔS° shows that increasing randomness at the solid/liquid

interface during the adsorption of Cd(II) ions on WASAC.

3.5 COMPARISON OF ADSORPTION CAPACITY OF WASAC WITH

OTHER ADSORBENT

In present study, the different parameters were investigated to get

equilibrium concentration as well as to determine the maximum adsorption with

isotherm model. The obtained adsorption capacity has been compared with

Chapter 3


ADSORBENTS

137

another reported adsorbents and given in Table 3.20, which shows that, the

WASAC has good adsorption capacity.

3.6 CONCLUSION

1) This study clearly suggests that, the use of WASAC as adsorbent is much

effective and economical, as it is abundant. It can be efficiently used to remove

cadmium ions up to 98.80% from aqueous solution.

2) The different operational parameters observed during the process of

investigations reveal that the contact time, initial concentration, adsorbent

mass, pH, stirring speed and temperature govern the overall process of

adsorption.

3) The experimental data fitted for both Langmuir and Freundlich isotherms. The

adsorption constants and regression factor indicates that the Langmuir fits

better than Freundlich isotherm with 28.33 mg/g maximum adsorption

capacity.

4) The increase in the adsorption capacity observed with increasing temperature

showed that the adsorption process was chemisorption, being feasible,

spontaneous and endothermic as confirmed by the evaluation of the relevant

thermodynamic parameters, viz. ∆H0, ΔG0 and ∆S0.

5) Kinetic study of the adsorption was tested with help of pseudo first and pseudo

second order models. From the results it was concluded that, pseudo first order

which has 13.652 mg/g equilibrium adsorption capacity was agreed more

finely than pseudo second order.

6) It could be concluded that, WASAC is a good adsorbent as it is inexpensive

and has high efficiency of adsorption of Cd(II) as well as abundantly available.

It could be applied for removal of Cd(II) from waste water effectively.

Chapter 3


ADSORBENTS

138

Table 3.1

Effect of pH on removal, % and amount adsorbed, mg/g of Cd(II)

Cd(II)=100 mg/dm3, Time = 240 min. T= 299 ± 2 K, WASAC=400 mg, agitation

speed = 150 rpm

pH Amount adsorbed, q mg/g Removal of Cd(II), %

1 4.61 36.88

2 5.32 42.58

3 7.98 63.78

4 10.34 82.73

5 11.79 94.31

6 12.35 98.80

6.5 12.35 98.80

7 12.35 98.80

Chapter 3


ADSORBENTS

139

Table 3.2

Effect of shaking period on removal, % and amount adsorbed, mg/g of Cd(II)

Cd(II)=100 mg/dm3, pH=6.5, T= 299 ± 2 K, WASAC=400 mg, agitation speed =

150 rpm

Time, min

Amount adsorbed, qt mg/g

Removal of Cd(II), %

30 3.98 31.78

60 6.56 52.48

90 7.80 62.42

120 10.36 82.22

180 11.35 90.78

210 11.84 94.72

240 12.35 98.80

300 12.35 98.80

360 12.35 98.80

Chapter 3


ADSORBENTS

140

Table 3.3

Effect of initial concentration of Cd(II) on amount adsorbed mg/g and removal, %

of Cd(II)

Time= 240min, pH=6.5, T= 299 ± 2 K, WASAC= 400 mg, agitation speed = 150

rpm

Initial Conc Cd(II)

mg/dm3

q mg/g amount

adsorbed

Removal of Cd(II) %

100 12.35 98.80

120 14.55 97.03

140 16.59 94.80

160 18.48 92.38

180 18.83 83.67

200 20.22 80.89

220 20.98 76.31

240 21.47 71.55

260 22.64 68.55

280 22.64 64.67

300 24.73 65.95

320 26.21 65.53

340 26.82 63.11

360 27.33 60.72

380 27.47 57.82

400 27.56 55.12

420 27.64 52.64

Chapter 3


ADSORBENTS

141

Table 3.4

Effect of adsorbent dosage on Cd(II) removal, % and amount adsorbed, mg/g

Cd(II) = 100 mg/dm3, Time= 240min, pH=6.5, T= 299 ± 2 K, agitation speed =

150 rpm

WASAC, mg Amount adsorbed, q mg/g Removal of Cd(II) %

50 5.05 5.05

100 6.94 13.88

150 7.25 21.77

200 9.26 37.0.3

250 9.43 47.11

300 10.11 60.63

350 10.81 75.73

370 12.29 90.92

390 12.34 96.24

400 12.35 98.80

Chapter 3


ADSORBENTS

142

Table 3.5

Effect on agitating speed of Cd(II) on removal, % and amount adsorbed, mg/g

Cd(II)=100 mg/dm3, time=240 min, T= 299 ± 2 K, WASAC= 400 mg, rpm= 150

Agitation speed, rpm Amount adsorbed, q mg/g Removal of Cd(II), %

50 4.71 37.67

70 6.53 52.24

100 7.83 62.6

120 10.91 87.30

130 12.21 97.70

140 12.35 98.80

150 12.35 98.80

160 12.35 98.80

180 12.35 98.80

200 12.35 98.80

Chapter 3


ADSORBENTS

143

Table 3.6

Adsorption isotherm for adsorption of Cd(II) on WASAC


rpm

Ce q

1.20 12.35

3.56 14.55

7.28 16.59

12.19 18.48

29.38 18.83

38.22 20.22

52.11 20.98

68.27 21.47

81.78 22.64

98.90 22.64

102.15 24.73

110.30 26.21

125.45 26.82

141.40 27.33

160.27 27.47

179.54 27.56

198.92 27.64

Chapter 3


ADSORBENTS

144

Table 3.7

Langmuir isotherm for adsorption of Cd(II) on WASAC


rpm

Ce Ce/q

1.20 0.0972

3.56 0.2454

7.28 0.4388

12.19 0.6596

29.38 1.5903

38.22 1.8902

52.11 2.4838

68.27 3.1798

81.78 3.6722

98.90 4.3684

102.15 4.1307

110.30 4.2083

125.45 4.6775

141.40 5.1738

160.27 5.8344

179.54 6.5145

198.92 7.1968

Table 3.8

Langmuir constant for the adsorption of Cd(II) on WASAC

qm (mg/g) KL (1/mg) R2

28.33 0.0967 0.986

Chapter 3


ADSORBENTS

145

Table 3.9

Freundlich adsorption isotherm for Cd(II) on WASAC


rpm

log Ce log qe

0.792 1.0917

0.5527 1.1628

0.8621 1.2199

1.086 1.2667

1.468 1.2749

1.5823 1.3058

1.7169 1.3218

1.8643 1.3318

1.9127 1.3477

1.9952 1.3549

2.0092 1.3932

2.0426 1.4185

2.0985 1.4285

2.1505 1.4366

2.2049 1.4388

2.2542 1.4403

2.2987 1.4415

Table 3.10

Freundlich constant for the adsorption of Cd(II) on WASAC

Kf n R2

11.280 5.935 0.953

Chapter 3


ADSORBENTS

146

Table 3.11

Pseudo first order for Cd(II) adsorption on WASAC


150 rpm

t min log (qe-qt)

0 1.0917

30 0.9227

60 0.7627

90 0.6580

120 0.2989

180 -0.0044

210 -0.2924

Chapter 3


ADSORBENTS

147

Table 3.12

Pseudo second order for Cd(II) adsorption on WASAC


150 rpm

t t/qt

0 0

30 7.5377

60 9.1464

90 11.5385

120 11.5830

180 15.8450

210 17.7365

240 19.4332

Table 3.13

Kinetic parameters for the adsorption of Cd(II) Ions onto WASAC

Pseudo first order Pseudo second order

qe exp.

(mg/g)

k1x10–3

(min–1)

qe calc.

(mg/g)

R2

k2 x10–3

qe calc.

(mg/g)

R2

12.35

0.65

13.652

0.982

0.0545

17.762

0.988

Chapter 3


ADSORBENTS

148

Table 3.14

Intraparticle diffusion plot at different temperature for adsorption of Cd(II) on

WASAC


150 rpm

t 1/2 qt

5.4773 3.98

7.7460 6.56

9.4869 7.80

10.9545 10.36

13.4164 11.35

14.4914 11.84

15.4919 12.35

Table 3.15

Study of intraparticle diffusion of adsorption of Cd(II) on WASAC

kid

(mg g−1min−1)

R2

0.834

0.961

Chapter 3


ADSORBENTS

149

Table 3.16

Effect of temperature on amount adsorbed of Cd(II) on WASAC

Cd(II)=420mg/dm3, Time= 240min, pH=6.5, WASAC= 400 mg, agitation speed =

150 rpm

T K Amount adsorbed, q mg/g

303 29.638

308 33.598

313 39.737

318 42.210

323 45.983

Chapter 3


ADSORBENTS

150

Table 3.17

Van't Hoff plots for removal of Cd(II) on WASAC

Cd (II)= 420mg/dm3, Time= 240min, pH=6.5, T= 299 ± 2 K, WASAC= 400 mg,

agitation speed = 150 rpm

1/T lnKc

0.00330 0.8633

0.00324 0.9887

0.00319 1.1566

0.00314 1.217

0.00309 1.3025

Table 3.18

Thermodynamic parameters of adsorption of Cd (II) on WASAC

T K

ΔG○, kJ/mol

∆H○, kJ/mol

∆S○, J/mol k

303 -1.110

1.582

5.707

308 -1.604

313 -1.824

318 -1.971

323 -2.115

Chapter 3


ADSORBENTS

151

Table 3.19

Comparison of adsorption capacity of WASAC with other adsorbent

Adsorbent qm (mg/g) Reference

Raw corn stalk

Acrylonitrile modified

3.39

12.73

[1]

[1]

Riverbed sand 0.150 [15]

Volcanic rocks a) Pumice

b) Scoria

3.84

2.24

[16]

[16]

Illitic clay 52.5 [21]

Kaolinite clay a) modified

b) unmodified

14.03

9.23

[24]

[24]

Loess soils 9.37 [26]

Mine tailing 3.52 [27]

Jordanian low grade phosphate 7.54 [29]

Zeolite tuff

Granulated activated carbon

5.157

17.153

[34]

[34]

Duolite ES 467 13.77 [44]

Carbon nanotubes

Oxidized with a) H2O2

b) KMnO4

c) HNO3

1.1

2.6

5.1

11.0

[48]

[48]

[48]

[48]

Bagasse fly ash 6.194 [51]

Bagasse fired fly ash 1.24 [52]

Coal fly ash pellets 18.98 [53]

Betel nut 1.12 [58]

Olive cores

Olive waste

12.56

6.55

[59]

[59]

Red alga Ceramium virgatum 39.7 [66]

Chapter 3


ADSORBENTS

152

Pycnoporus sanguineus 3.18 [68]

Brewer’s yeast 10.17 [72]

Corncob

Oxidized with 1M nitric acid

4.73

19.3

[78]

[78]

Raw corn stalk

Modified using graft copolymerization

3.81

22.17

[79]

[79]

Olive cake 10.56 [81]

Olive stone activated carbons 1.85 [84]

Rice husk 21.28 [85]

Raw rice husk

Epichlorohydrin treated rice husk

NaOH treated rice husk

Sodium bicarbonate treated rice husk

8.58

11.12

20.24

16.18

[86]

[86]

[86]

[86]

Wheat bran 0.703 [88]

Wheat bran 15.71 [89]

Castor (Ricinus communis) seed hull 6.98 [93]

Walnut tree sawdust 5.76 [97]

Jack fruit seed carbon 1.215 [100]

Ceiba pentandra hulls activated carbon 19.5 [102]

Bamboo charcoal 12.08 [104]

Cashew nut shell activated carbon 14.29 [105]

Wood apple shell activated carbon 27.64 Present study

Chapter 3


ADSORBENTS

153

.

0

20

40

60

80

100

0 2 4 6 8

pH

Rem

oval o

f C

d(II), %

0

2

4

6

8

10

12

14

Am

ou

nt ad

so

rbed

of C

d(II), m

g/g

Fig. 3.1

Effect of pH on removal of Cd(II), % and amount adsorbed, mg/g

Cd(II)=100 mg/dm3, time = 240 min. T= 299 ± 2 K, WASAC=400 mg, agitation

speed = 150 rpm

Chapter 3


ADSORBENTS

154

0

20

40

60

80

100

0 100 200 300 400

Time, min

Rem

oval o

f C

d(II), %

0

2

4

6

8

10

12

14

Am

ount adsorb

ed o

f C

d(II), m

g/g

Fig. 3.2

Effect of shaking period on removal of Cd(II), % and amount adsorbed, mg/g


150 rpm

Chapter 3


ADSORBENTS

155

0

20

40

60

80

100

0 100 200 300 400 500

Initial conc. Cd(II), mg/dm3

Rem

oval o

f C

d(II), %

0

5

10

15

20

25

30

Am

ou

nt ad

so

rbed

of C

d(II), m

g/g

Fig. 3.3

Effect of initial concentration of Cd(II) on amount adsorbed, mg/g and removal, %

of Cd(II)

Time=240min, pH=6.5, T= 299 ± 2 K, WASAC= 400 mg, agitation speed = 150

rpm

Chapter 3


ADSORBENTS

156

0

2

4

6

8

10

12

14

0 100 200 300 400 500

Adsorbent dose mg

Am

ount ad

sorb

ent C

d(II) m

g/g

0

20

40

60

80

100

Rem

oval

Cd(II) %

Fig. 3.4

Effect of adsorbent dosage on Cd(II) removal, % and amount adsorbed, mg/g

Cd(II) = 100mg/dm3, time=180min, pH=6.5, T= 299 ± 2 K, agitation speed = 150

rpm

Chapter 3


ADSORBENTS

157

0

20

40

60

80

100

0 50 100 150 200 250

rpm

Rem

ova

l of C

d(II), %

0

2

4

6

8

10

12

14

Am

ount ad

sorb

ed o

f C

d(II), m

g/g

Fig. 3.5

Effect on agitating speed on removal of Cd(II), % and amount adsorbed, mg/g

Cd(II)=100 mg/dm3, time=240 min, T= 299 ± 2 0K, WASAC=400 msg, agitation

speed = 150 rpm

Chapter 3


ADSORBENTS

158

0

5

10

15

20

25

30

0 50 100 150 200 250

Ce mg/dm3

qe m

g/g

Fig. 3.6

Adsorption isotherm for adsorption of Cd(II) adsorption on WASAC


rpm

Chapter 3


ADSORBENTS

159

0

1

2

3

4

5

6

7

8

0 50 100 150 200 250

Ce

Ce/q

Fig. 3.7

Langmuir isotherm for adsorption of adsorption of Cd(II) on WASAC


rpm

Chapter 3


ADSORBENTS

160

0

0.4

0.8

1.2

1.6

0 0.5 1 1.5 2 2.5

log Ce

log

qe

Fig. 3.8

Freundlich adsorption isotherm for adsorption of Cd(II) on WASAC


rpm

Chapter 3


ADSORBENTS

161

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 50 100 150 200 250

t min

log

(q

e-q

t)

Fig. 3.9

Pseudo first order for adsorption of Cd(II) on WASAC


150 rpm

Chapter 3


ADSORBENTS

162

0

5

10

15

20

25

0 50 100 150 200 250 300

t min

t/qt

Fig. 3.10

Pseudo second order for adsorption of Cd(II) on WASAC


150 rpm

Chapter 3


ADSORBENTS

163

0

2

4

6

8

10

12

14

0 5 10 15 20

t1/2

qt

Fig. 3.11

Intraparticle diffusion plot for adsorption of Cd(II) on WASAC


150 rpm

Chapter 3


ADSORBENTS

164

0

10

20

30

40

50

300 305 310 315 320 325

T K

Am

ou

nt

ad

so

rbe

nt

of

Cd

(II)

, mg

/g

Fig. 3.12

Effect of temperature on amount adsorbed of Cd(II) on WASAC

Cd(II)=420 mg/dm3, Time=240min, pH=6.5, T= 299 ± 2 K, WASAC= 400 mg,


Chapter 3


ADSORBENTS

165

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0.00305 0.0031 0.00315 0.0032 0.00325 0.0033 0.00335

1/T K

ln K

c

Fig. 3.13

Van't Hoff plots for adsorption of Cd(II) on WASAC

Cd(II) = 420 mg/dm3,Time=240min, pH=6.5, T= 299 ± 2 K, WASAC= 400 mg,


Chapter 3


ADSORBENTS

166

References

[1] L. Zheng, Z. Dang, X. Yi, H. Zhang, Equilibrium and kinetic studies of

adsorption of Cd(II) from aqueous solution using modified corn stalk, J.

Hazard. Mater. 176 (2010) 650–656.

[2] M. Athar, S. B. Vohora, Heavy Metals and Environment , Wiley Eastern

Ltd., New Age International publishers Ltd., New Delhi, (1995).

[3] K. Kadirvelu, C. Namasivayam, Activated carbon from coconut coirpith as

metal adsorbent: adsorption of Cd(II) from aqueous solution, Adv. Environ.

Res. 7 (2003) 471–478.

[4] L. Nouri, O. Hamdaoui, Ultrasonication-assisted sorption of cadmium

from aqueous phase by wheat bran, J. Phys. Chem. A 111 (2007) 8456-

8463

[5] A. F. Tajar, T. Kaghazchi, M. Soleimani Adsorption of cadmium from

aqueous solutions on sulfurized activated carbon prepared from nut shells

J. Hazard. Mater. 165 (2009) 1159–1164.

[6] Cadmium in Drinking-water, WHO Guidelines for Drinking-water Quality,

Edition 3rd, Geneva, Switzerland (2008).

[7] W. Wang, V. Fthenakis, Kinetics study on separation of cadmium from

tellurium in acidic solution media using ion-exchange resins J. Hazard.

Mater. 125 (2005) 80-88.

[8] J. Nakajima, M. Fujinami, K. Oguma, A Novel separation and

preconcentration method for traces manganese, cobalt, zinc and cadmium

using coagulation of colloidal silica, Anal. Sci. 20 (2004) 1733-1736.

[9] S. E. Ghazy, G. A. Mostafa, Separation of cadmium (II), mercury (II),

bismuth (III) and antimony (III) from drinking and river waters by flotation,

Canad. J. Anal. Sci. Spectro. 53 (2008) 28-35.

[10] K. Inagaki, A. Takatsu, A. Uchiumi, A. Nakama, K. Okamoto,

Determination of cadmium in sediment by isotope dilution inductively

Chapter 3


ADSORBENTS

167

coupled plasma mass spectrometry using a co- precipitation separation

technique, J. Anal. At. Spectrom. 16 (2001) 1370–1374.

[11] C. P. Mane, Analytical applications of 2-octylaminopyridine, Ph. D.

Thesis, Shivaji University, Kolhapur, India. (2008).

[12] A. M. Urtiaga, A. Alonso, I. Ortiz, J. A. Daoud, S. A. El-Reefy, S. Pérez

de Ortiz, T. Gallego, Comparison of liquid membrane processes for the

removal of cadmium from wet phosphoric acid, J. Memb. Sci. 164 (2000)

229-240.

[13] B. Bansal, r. Mahajan, Md M. Hossain, M. S. Liaw, Application of liquid

membrane to recover cadmium, Dev. Chem. Eng. Mineral Process. 14

(2006) 227-238.

[14] M. A. Awan, I. A. Qazi, I. Khalid, Removal of heavy metals through

adsorption using sand, J. Environ. Sci. 15 (2003) 413-416.

[15] Y.C. Sharma, S.N. Kaul, C.H. Weng, Adsorptive separation of cadmium

from aqueous solutions and wastewaters by riverbed sand, Environ. Pollut.

150 (2007) 251-257.

[16] E. Alemayehu, B. Lennartz, Virgin volcanic rocks: Kinetics and

equilibrium studies for the adsorption of cadmium from water, J. Hazard.

Mater. 169 (2009) 395–401.

[17] L. Pappalardo, F. Jumean, N. Abdo, Removal of Cadmium, Copper, Lead

and Nickel from Aqueous Solution by White, Yellow and Red United Arab

Emirates Sand, Am. J. Environ. Sci. 6 (2010) 41-44.

[18] D. Quintanilla, I. Hierro, M. Fajardo, I. Sierra, Adsorption of cadmium (II)

from aqueous media onto a mesoporous silica chemically modified with 2-

mercaptopyrimidine, J. Mater. Chem. 16 (2006) 1757–1764.

[19] Y. C. Sharma, V. Shrivastava, Adsorption of cadmium from aqueous

solutions by an indigenous clay mineral, Ind. J. Chem. Technol. 13 (2006)

218-221.

Chapter 3


ADSORBENTS

168

[20] Y.C. Sharma, Thermodynamics of removal of cadmium by adsorption on

an indigenous clay, Chem. Eng. J. 145 (2008) 64–68.

[21] I. G. Abid, K. Galai, M. T. Ayadi, Retention of chromium (III) and

cadmium (II) from aqueous solution by illitic clay as a low-cost adsorbent,

Desalination 256 (2010) 190–195.

[22] M. G. da Fonseca, M. M. de Oliveira, L. N.H. Arakaki, Removal of

cadmium, zinc, manganese and chromium cations from aqueous solution

by a clay mineral, J. Hazard. Mater. B137 (2006) 288–292.

[23] C. N. Haas, N. D. Horowitz, Adsorption of cadmium to kaolinite in the

presence of organic material, Water, Air, Soil Pollut. 27 (1986) 131-140.

[24] K. O. Adebowale, I. E. Unuabonah, B. I. Olu-Owolabi, The effect of some

operating variables on the adsorption of lead and cadmium ions on

kaolinite clay, J. Hazard. Mater. B134 (2006) 130–139.

[25] E. I. Unuabonah, B. I. Olu-Owolabi, E. I. Fasuyi, K. O. Adebowale,

Modeling of fixed-bed column studies for the adsorption of cadmium onto

novel polymer–clay composite adsorbent, J. Hazard. Mater. 179 (2010)

415–423.

[26] Y. Wang, X. Tang, Y. Chen, L. Zhan, Z. Li, Q. Tang, Adsorption behavior

and mechanism of Cd(II) on loess soil from China, J. Hazard. Mater. 172

(2009) 30–37.

[27] T. Shi, S. Jia, Y. Chen, Y.Wen, C. Du, H. Guo, Z. Wang, Adsorption of

Pb(II), Cr(III), Cu(II), Cd(II) and Ni(II) onto a vanadium mine tailing from

aqueous solution, J. Hazard. Mater. 169 (2009) 838–846.

[28] G. R. Porras, J.B. G. Magno, M.P. G. Muñoz, Lead and cadmium

immobilization on calcitic limestone materials, Desalination 262 (2010)

1–10.

[29] M. I. Kandah, Zinc and cadmium adsorption on low-grade phosphate,

Sep. Purif. Technol. 35 (2004) 61–70.

Chapter 3


ADSORBENTS

169

[30] G. Mustafa, B. Singh, R. S. Kookana, Cadmium adsorption and desorption

behaviour on goethite at low equilibrium concentrations: effects of pH

and index cations, Chemosphere 57 (2004) 1325–1333.

[31] K. Rout, M. Mohapatra, B. K. Mohapatra, S. Anand, Pb(II), Cd(II) and

Zn(II) adsorption on low grade manganese ore, Int. J. Eng. Sci. Technol.

1 (2009) 106-122.

[32] D.B. Singh, D.C. Rupainwar, G. Prasad, K.C. Jayaprakas, Studies on the

Cd(II)/ removal from water by adsorption, J. Hazard. Mater. 60 (1998)

29–40.

[33] A. Sarı, M. Tuzen, Kinetic and equilibrium studies of Pb(II) and Cd(II)

removal from aqueous solution onto colemanite ore waste, Desalination

249 (2009) 260–266.

[34] M. Minceva, L. Markovska, V. Meshko, Removal of Zn2+, Cd2+ And

Pb2+ from binary aqueous solution by natural zeolite and granulated

activated carbon, Maced. J. Chem. Chem. Eng. 26 (2007)125–134.

[35] J. T.Bamgbose, S. Adewuyi, O.Bamgbose, A. A.Adetoye, Adsorption

kinetics of cadmium and lead by chitosan, Afr. J. Biotechnol. 9 (2010)

2560-2565.

[36] R. Laus, T. G. Costa, B. Szpoganicz, V. T. Favere, Adsorption and

desorption of Cu(II), Cd(II) and Pb(II) ions using chitosan crosslinked with

epichlorohydrin-triphosphate as the adsorbent, J. Hazard. Mater. 183 (2010)

233–241.

[37] S. Hasan, A. Krishnaiah, T. K. Ghosh, D. S. Viswanath, Adsorption of

divalent Cadmium (Cd(II)) from aqueous solutions onto chitosan-coated

perlite bads, Ind. Eng. Chem. Res. 45 (2006) 5066-5077.

[38] M. L. Cervera, M. C. Arnal, M. Guardia, Removal of heavy metals by

using adsorption on alumina or chitosan, Anal. Bioanal. Chem. 375

(2003) 820–825.

Chapter 3


ADSORBENTS

170

[39] J. C. Ryu, H. K. Jeon, K. S. Park, Adsorption and removal of heavy metals

by chitosan-phthalocyanine complex, J. Chitin Chitosan 9 (2004) 85-88.

[40] M. S. Rodríguez, M. S. Zalba A. L. Debbaudt, E. Agullo, New chitosan–

calcium pectinate pellets and their adsorption capacity, Colloid. Polym.

Sci. 285 (2006) 119–124.

[41] V. Singh, S. Pandey, S.K. Singh, R. Sanghi, Removal of cadmium from

aqueous solutions by adsorption using poly(acrylamide) modified guar

gum–silica nanocomposites, Sep. Purif. Technol. 67 (2009) 251–261.

[42] T.S. Anirudhan, P.G. Radhakrishnan, Kinetic and equilibrium modelling

of Cadmium (II) ions sorption onto polymerized tamarind fruit shell,

Desalination 249 (2009) 1298–1307.

[43] Buhani, Narsito, Nuryono, E. Sri Kunarti, Production of metal ion

imprinted polymer from mercapto–silica through sol–gel process as

selective adsorbent of cadmium, Desalination 251 (2010) 83–89.

[44] K. S. Rao, G. R. Chaudhury, B.K. Mishra, Kinetics and equilibrium

studies for the removal of cadmium ions from aqueous solutions using

Duolite ES 467 resin, Int. J. Miner. Process. (2010) (article in press)

doi:10.1016/j.minpro.2010.08.003.

[45] C.H. Xiong, C.P. Yao, Study on the adsorption of cadmium(II) from

aqueous solution by D152 resin, J. Hazard. Mater. 166 (2009) 815–820.

[46] L. Dong, Z. Zhu, H. Ma, Y. Qiu, J. Zhao, Simultaneous adsorption of lead

and cadmium on MnO2-loaded resin, J. Environ. Sci. 2 (2010) 225–229.

[47] N.V.P.Aguilar, E. M. Sandoval, P. E. D. Flores, J. R. R. Mendez,

Adsorption of cadmium and lead onto oxidized nitrogen-doped multiwall

carbon nanotubes in aqueous solution: equilibrium and kinetics, J.

Nanopart. Res. 12 (2010) 467–480.

Chapter 3


ADSORBENTS

171

[48] Y. H. Li, S. Wang, Z. Luan, J. Ding, C. Xu, D. Wu, A dsorption of

cadmium(II) from aqueous solution by surface oxidized carbon nanotubes,

Carbon 41 (2003) 1057–1062.

[49] G. D. Vukovic, A. D. Marinkovic, M. Colic, M. Ð. Ristic, R. Aleksic, A.

A. P. Grujic, P. S. Uskokovic, Removal of cadmium from aqueous

solutions by oxidized and ethylenediamine-functionalized multi-walled

carbon nanotubes, Chem. Eng. J. 57 (2010) 238–248.

[50] S. Wang, H. Wu, Review,Environmental-benign utilisation of fly ash as

low-cost adsorbents, J. Hazard. Mater. B136 (2006) 482–501.

[51] V. C. Srivastava, I. D. Mall, I. M. Mishra, Equilibrium modelling of single

and binary adsorption of cadmium and nickel onto bagasse fly ash, Chem.

Eng. J. 117 (2006) 79–91.

[52] V. K. Gupta, C.K. Jain, I. Ali, M. Sharma, V.K. Saini, Removal of

cadmium and nickel from wastewater using bagasse fly ash—a sugar

industry waste, Wat. Res. 37 (2003) 4038–4044.

[53] A. Papandreou, C.J. Stournaras, D. Panias, Copper and cadmium

adsorption on pellets made from fired coal fly ash, J. Hazard. Mater. 148

(2007) 538–547.

[54] A. Bhatnagar, A. K. Minocha, Utilization of industrial waste for cadmium

removal from water and immobilization in cement, Chem. Eng. J. 150

(2009) 145–151.

[55] N. Balkaya, H. Cesur, Adsorption of cadmium from aqueous solution by

phosphogypsum, Chem. Eng. J. 140 (2008) 247–254.

[56] S. Çay, A. Uyanık, A. Özasık, Single and binary component adsorption of

copper(II) andcadmium(II) from aqueous solutions using tea-industry

waste, Sep. Purif. Technol. 38 (2004) 273–280.

Chapter 3


ADSORBENTS

172

[57] L. Ming, X. Xiao L. Lian, Biosorption Of Cadmium(II) From Aqueous

Solutions By Industrial Fungus Rhizopus Cohnii, Nonferrous Met. Soc.

China 20 (2010) 1104–1111.

[58] W. Zheng, X. Li, F. Wang, Q. Yang, P. Dengb, G. Zeng, Adsorption

removal of cadmium and copper from aqueous solution by areca—A food

waste, J. Hazard. Mater. 157 (2008) 490–495.

[59] N. Azouaou, Z. Sadaoui, H. Mokaddem, Removal of cadmium from

aqueous solution by adsorption on vegetable wastes, J. Appl. Sci. 8

(2008) 4638-4643.

[60] A.B. P. Marın, V. M. Zapata, J.F. Ortuno, M. Aguilar, J. Saez, M. Llorens,

Removal of cadmium from aqueous solutions by adsorption onto orange

waste J. Hazard. Mater. B139 (2007) 122–131.

[61] X. Li, Y. Tang, X. Cao, D. Lu, F. Luo, W. Shao, Preparation and

evaluation of orange peel cellulose adsorbents for effective removal of

cadmium, zinc, cobalt and nickel, Colloids Surfaces A: Physicochem.

Eng. Aspects 317 (2008) 512–521.

[62] X. Li, Y. Tang, Z. Xuan, Y. Liu, F. Luo, Study on the preparation of

orange peel cellulose adsorbents and biosorption of Cd2+ from aqueous

solution, Sep. Purif. Technol. 55 (2007) 69–75.

[63] E. Pehlivan, B.H. Yanık, G. Ahmetli, M. Pehlivan, Equilibrium isotherm

studies for the uptake of cadmium and lead ions onto sugar beet pulp,

Bioresource Technol. 99 (2008) 3520–3527.

[64] R. J.E. Martins, R. Pardo, R. A.R. Boaventur, Cadmium(II) and zinc(II)

adsorption by the aquatic moss Fontinalis antipyretica: effect of

temperature, pH and water hardness, Water Res. 38 (2004) 693-699.

[65] R. Herrero, P. Lodeiro, R. Rojo, A. Ciorba, P. Rodrıguez, M. E. S. de

Vicente, The efficiency of the red alga Mastocarpus stellatus for

Chapter 3


ADSORBENTS

173

remediation of cadmium pollution, Bioresource Technol. 99 (2008) 4138–

4146.

[66] A. Sarı, M. Tuzen, Biosorption of cadmium(II) from aqueous solution by

red algae (Ceramium virgatum): Equilibrium, kinetic and thermodynamic

studies, J. Hazard. Mater. 157 (2008) 448–454.

[67] J. T. Matheickal, Q. Yu, G. M. Woodburn, Biosorption of cadmium(II)

from aqueous solutions by pre-treated biomass of marine alga durvillaea

potatorum, Wat. Res. 33 (1999) 335-342.

[68] M.D. Mashitah, Y. Y. Azila, S. Bhatia, Biosorption of cadmium (II) ions

by immobilized cells of Pycnoporus sanguineus from aqueous solution,


[69] F. A. A. Al-Rub, M. Kandah, N. Al-Dabaybeh, Competitive Adsorption of

Nickel and Cadmium on Sheep Manure Wastes: Experimental and

Prediction Studies, Sep. Sci. Technol. 38 (2003) 483–497.

[70] X. Zheng, B. Li, B. Zhu, R. Kuang, X. Kuang, B. Xu, M. Ma, Crayfish

carapace micro-powder (CCM): A novel and efficient adsorbent for

heavy metal ion removal from wastewater, Water 2 (2010) 257-272.

[71] A. H. Mahvi, D. Naghipour, F. Vaezi, S. Nazmara, Teawaste as An

Adsorbent for Heavy Metal Removal from Industrial Wastewaters,

Am. J. Appl. Sci. 2 (2005) 372-375.

[72] L. Cui, G. Wu, T. Jeong, adsorption performance of nickel and cadmium

ions onto brewer’s yeast, The Can. J. Chem. Eng. 88 (2010) 109-115.

[73] U. Garg, M.P. Kaur, G.K. Jawa, D. Sud, V.K. Garg Removal of cadmium

(II) from aqueous solutions by adsorption on agricultural waste biomass, J.

Hazard. Mater. 154 (2008) 1149–1157.

[74] N.V. Farinella, G.D. Matos, E.L. Lehmann, M.A.Z. Arruda, Grape

bagasse as an alternative natural adsorbent of cadmium and lead for

effluent treatment, J. Hazard. Mater. 154 (2008) 1007–1012.

Chapter 3


ADSORBENTS

174

[75] Y. Hoa, A. E. Ofomaja, Biosorption thermodynamics of cadmium on

coconut copra meal as biosorbent, Biochem. Eng. J. 30 (2006) 117–123.

[76] G.C. Panda, S.K. Das, S. Chatterjee, P.B. Maity, T.S. Bandopadhyay, A.K.

Guhaa, Adsorption of cadmium on husk of Lathyrus sativus: Physico-

chemical study, Colloid Surfaces B 50 (2006) 49–54.

[77] J. Shen, Z. Duvnjak, Adsorption kinetics of cupric and cadmium ions

on corncob particles, Process Biochem. 40 (2005) 3446–3454.

[78] R. L. Ramos, L.A. B. Jacome, I. A.Rodriguez, Adsorption of cadmium (II)

from aqueous solution on natural and oxidized corncob, Sep. Purif.

Technol. 45 (2005) 41–49.

[79] L. Zheng, Z. Dang, C. Zhu, X. Yi, H. Zhang, Congqiang Liu, Removal of

cadmium(II) from aqueous solution by corn stalk graft copolymers,


[80] O. Hamdaoui, Removal of cadmium from aqueous medium under

ultrasound assistance using olive leaves as sorbent, Chem. Eng. Proc. 48

(2009) 1157–1166.

[81] S. Doyurum, A. Celik, Pb(II) and Cd(II) removal from aqueous solutions

by olive cake, J. Hazard. Mater. B138 (2006) 22–28.

[82] Z. A. Al-Anber, M. A. D. Matouq, Batch adsorption of cadmium ions

from aqueous solution by means of olive cake, J. Hazard. Mater. 151

(2008) 194–201.

[83] Z. Elouear, J. Bouzid, N. Boujelben, M. Feki, A. Montiel, The use of

exhausted olive cake ash (EOCA) as a low cost adsorbent for the removal

of toxic metal ions from aqueous solutions, Fuel 87 (2008) 2582–2589.

[84] I. Kula, M. Ugurlu, H. Karaoglu, A. Celik, Adsorption of Cd (II) ions from

aqueous solutions using activated carbon prepared from olive stone by

ZnCl2 activation, Bioresource Technol. 99 (2008) 492–501.

Chapter 3


ADSORBENTS

175

[85] P. S. Kumar, K. Ramakrishnan, S. D. Kirupha, S. Sivanesan,

Thermodynamic and kinetic studies of cadmium adsorption from aqueous

solution onto rice husk, Braz. J. Chem. Eng. 27 (2010) 347 – 355.

[86] U. Kumar, M. Bandyopadhyay, Sorption of cadmium from aqueous

solution using pretreated rice husk, Bioresource Technol. 97 (2006)

104–109.

[87] V. C. Srivastava, I. D. Mall, I. M. Mishra, Characterization of mesoporous

rice husk ash (RHA) and adsorption kinetics of metal ions from aqueous

solution onto RHA, J. Hazard. Mater. B134 (2006) 257–267.

[88] K.K. Singh, A.K. Singh, S.H. Hasan, Low cost bio-sorbent ‘wheat bran’

for the removal of cadmium from wastewater: Kinetic and equilibrium

studies, Bioresource Technol. 97 (2006) 994–1001.

[89] L. Nouri, I. Ghodbane, O. Hamdaoui, M. Chiha, Batch sorption dynamics

and equilibrium for the removal of cadmium ions from aqueous phase

using wheat bran, J. Hazard. Mater. 149 (2007) 115–125.

[90] A. Ozer, H.B. Pirincci, The adsorption of Cd(II) ions on sulphuric acid-

treated wheat bran, J. Hazard. Mater. B137 (2006) 849–855.

[91] E. W. Shin, K.G. Karthikeyan, M. A. Tshabalala, Adsorption mechanism

of cadmium on juniper bark and wood, Bioresource Technol. 98 (2007)

588–594.

[92] C. M. Zvinowanda, J. O. Okonkwo, P. N. Shabalala, N. M. Agyei, A novel

adsorbent for heavy metal remediation in aqueous Environments, Int. J.

Environ. Sci. Tech. 6 (2009) 425-434.

[93] T. K. Sen, M. Mohammod, S. Maitra, B. K. Dutta, Removal of Cadmium

from aqueous solution using castor seed hull: A kinetic and equilibrium

study, Clean – Soil, Air, Water 38 (2010) 850–858.

Chapter 3


ADSORBENTS

176

[94] A.H. Mahvi, F. Gholami, S. Nazmara, Cadmium biosorption from

wastewater by ulmus leaves and their ash, Europ. J. Sci. Res. 23 (2008)

197-203.

[95] A. Sharma, K. G. Bhattacharyya, Azadirachta indica (Neem) leaf powder

as a biosorbent for removal of Cd(II) from aqueous medium, J. Hazard.

Mater. B125 (2005) 102–112.

[96] T. K. Naiya, P. Chowdhury, A. K. Bhattacharya, S. K. Das, Saw dust and

neem bark as low-cost natural biosorbent for adsorptive removal of Zn(II)

and Cd(II) ions from aqueous solutions, Chem. Eng. J. 148 (2009) 68–79.

[97] B. Yasemin, T. Zek, Removal of heavy metals from aqueous solution by

sawdust adsorption, J. Environ. Sci. 19 (2007) 160-166.

[98] K. K.H. Choy, G. McKay, Sorption of cadmium, copper, and zinc ions

onto bone char using Crank diffusion model, Chemosphere 60 (2005)

1141–1150.

[99] B. S. Inbaraj, N. Sulochana, Carbonised jackfruit peel as an adsorbent

for the removal of Cd(II) from aqueous solution, Bioresource Technol.

94 (2004) 49–52.

[100] N. Kannan, T. Veemaraj, Batch adsorption dynamics and equilibrium

studies forthe removal of cadmium (II) ions from aqueous solution using

jack fruit seed and commercial activated carbons – a comparative study,

EJEAFChe. 9 (2010) 327-336.

[101] M. Kazemipour, M. Ansari, S. Tajrobehkar, M. Majdzadeh, H. R.

Kermani, Removal of lead, cadmium, zinc, and copper from industrial

wastewater by carbon developed from walnut, hazelnut, almond,

pistachio shell, and apricot stone, J. Hazard. Mater. 150 (2008) 322–327.

[102] M. M. Rao, A. Ramesh, G. P. C. Rao, K. Seshaiah, Removal of copper

and cadmium from the aqueous solutions by activated carbon derived

from Ceiba pentandra hulls, J. Hazard. Mater. B129 (2006) 123–129.

Chapter 3


ADSORBENTS

177

[103] L. C. Guerrero, R. R. Mendez, E. M. Sandoval, D. A. Cullen, D. J. Smith,

H. Terrones, M. Terrones, Production and detailed characterization of

bean husk-based carbon: Efficient cadmium (II) removal from aqueous

solutions, Wat. Res. 42 (2008) 3473 – 3479.

[104] F. Y. Wang, H. Wang, J. W. Ma, Adsorption of cadmium (II) ions from

aqueous solution by a new low-cost adsorbent—Bamboo charcoal

adsorption of cadmium (II) ions from aqueous solution by a new low-cost

adsorbent—Bamboo charcoal, J. Hazard. Mater. 177 (2010) 300–306.

[105] S. Tangjuank, N. Insuk, J. Tontrakoon, V. Udeye, Adsorption of

Lead (II) and Cadmium (II) ions from aqueous solutions by adsorption on

activated carbon prepared from cashew nut shells, World Acad. Sci. Eng.

Technol. 52 (2009) 110-116.

[106] M. Kobya, E. Demirbas, E. Senturk, M. Ince, Adsorption of heavy metal

ions from aqueous solutions by activated carbon prepared from apricot

stone, Bioresource Technol. 96 (2005) 1518–1521.

[107] J. Goel, K. Kadirvelu, C. Rajagopal, V. K. Garg, Cadmium(II) uptake

from aqueous solution by adsorption onto carbon aerogel using a

response surface methodological approach, Ind. Eng. Chem. Res.

45(2006) 6531-6537.

[108] R. C. Bansal, M. Goyal, Activated Carbon Adsorption, CRC Press,

Taylor & Francis Group, Boca Raton (2005) 345.

[109] B. J. Suder, J.P. Wightman, Adsorption from solution, Proceeding of a

symposium, Bristol, (1982), Academic press, Londaon, (1983) 235.

kinetic and equilibrium studies of the adsorption of cd...

Documents