12

Chapter – II

LITERATURE REVIEW

Various methods are operated to remove the heavy metals from effluents. These

methods include ion-exchange, reverse osomosis, electrodialysis, precipitation,

etc. Biosorption is gaining importance due to abantantly, easily and freely

available biosorbents. This chapter contains the literature available to the author

from various sources – university library, journals and internet.

Chromium

The batch removal of chromium (VI) from aqueous solutions by Fagas orientalis

L. (Beech) saw dust was investigated by Acar and Malkoc [1]. Optimum time was

found to be 80 min. The biosorption of chromium (VI) was rapidly increased with

increase in concentration. Maximum biosorption efficiency occurred at pH 1.0.

Both Langmuir and Freundlich isotherms fitted well to equilibrium data. The

maximum uptake was 16.13 mg/g by Langmuir’s model.

Agarwal et al [2] studied the effectiveness of Tamarindus Indica seed (TS),

crushed Coconut Shell (CS), Almond Shell (AS), Ground Nut Shell (GS) and

Walnut Shell (WS) for Cr (VI) biosorption. At pH 4, Cr (VI) removal was 30, 36,

35, 40 and 80% for CS, AS, GS, WS and TS respectively. Equilibrium time was

60, 120, 150 and 120 min for GS, WS and TS respectively. Removal of Cr (VI)

increased with increase of temperature for TS. First order reversible model fitted

well for all the sorbents. Freundlich isotherm fitted better than Langmuir isotherm

for the equilibrium data. Downflow column studies were conducted for evaluation

of TS for Cr (VI) removal.

13

Aksu and Balibek [3] studied the chromium (VI) biosorption by dried Rhizopus

arrhizus as a function of pH, initial chromium (VI) and salt (NaCl) concentrations

in a batch system. Equilibrium was reached at 60 min. The maximum Cr (VI)

sorption capacity was obtained at pH = 2.0 both in the absence and presence of

increasing concentrations of the salt.In the absence of salt, when the initial

chromium (VI) concentration increased from 25 to 250 mg/L, the loading capacity

increased from 23.2 to 108.9 mg/g due to the increase in the number of ions

competing for the available binding sites on the biomass surface. The uptake of

chromium (VI) reached a plateau at 250 mg/L showing the saturation of binding

sites at higher concentration levels. As the concentration of salt increased from 0

to 50 g/L, the amount of chromium (VI) adsorbed by dried R.arrhizus and

chromium (VI) removal yield diminished from 23.2 to 18.4 mg/g and from 92.1 to

72.2%. Langmuir–Freundlich (Sips) model was best fitted at all salt

concentrations.

The ability of low rank Turkish brown coals (Ilgin: BC1, Beysehir: BC2 and

Ermenite: BC3) to remove chromium (VI) from aqueous solutions was studied by

Arslan and Pehlivan [4] and compared the data with the values obtained with

activated carbon (AQ-30). The optimum biosorption took place at 80 min for all

the sorbents. The sorption capacities of the brown coals and activated carbons

were 11.2, 12.4, 7.4 and 6.8 mM/g of BC1, BC2, BC3 and AQ-30 respectively at

pH = 3.0. The percentage biosorption of BC2, BC3 and AQ-30 increased with an

increase in pH upto 3.0 (100 %, 60 % and 52 % respectively) and decreased

rapidly for the further increase in pH. The percentage biosorption was maximum

at pH = 2.3 for BC1. Equilibrium tests showed that the chromium (VI) removal

14

was fitted with Freundlich isotherm. The Go, Ho and So values were

calculated to be -4302.71 J/mol, -10,175.87 J/mol and -20.03 J/K-mol for BC1; -

6448.8 J/mol, -17,417.368 J/mol and -37.41 J/K-mol for BC2; -405.6 J/mol, -

1867.85 J/mol and -4.98J/K-mol for BC3 and -118.81 J/mol, -713.82 J/mol and

2.02 J/K-mol for AQ-30 respectively.

Ashok et al [5] studied removal of Cr (VI) from aqueous solutions by Yarrowia

lipolytica (NCIM 3589 and 3590). At pH 1.0 and temperature of 35oC, maximum

biosorption was observed. Equilibrium was reached within 2 h. With the increase

of biomass and sea salts, metal uptake decreased. For NCIM 3589 and 3590, the

biosorption capacities increased from 5.25 to 63.73 mg/g and 4.26 to 49.09 mg/g

respectively with increase in Cr (VI) concentration from 50 to 950 mg/L. Both

Langmuir and Freundlich isotherms fitted well to biosorption data.

Characterization of the biomass is analysed by SEM, XRD and FTIR

spectroscopy.

Batch experiments were carried out by Baran et al [6] for biosorption Cr (VI) ions

on chitin, chiotosan, purolite CT-275 (purolite I), purolite MN-500 (purolite II)

and Amberlite XAd-7. The optimum pH was found to be 3.0, 3.0, 7.0, 7.0 and 8.0

for chitin, chitosan, purolite I, purolite II and Amberlite XAd-7 respectively. The

equilibrium time was 50, 30, 30, 40 and 50 min for chitin chitosan, purolite I,

purolite II and Amberlite XAd-7 respectively. The maximum adsorption

capacities of 153.85 mg/g for chitosan, 126.56 mg/g for purolite II, 89.29 mg/g for

purolite I and 70.42 mg/g for chitin were attained. The adsorption data could be

accurately interpreted by Langmuir equation for chitosan, chitin, purolite I and

15

purolite II and by the Freundlich equation for chitosan, chitin and Amberlite

XAd-7.

Baral et al [7] studied Cr (VI) removal from aqueous solution by onto treated saw

dust. The percentage biosorption was increased from 20% to 100%, as dosage

increased from 02 g/L to 1.6 g/L. As the temperature increased from 303 to 313 K,

percentage biosorption decreased from 91% to 48%. Maximum removal was

found to be in the pH range of 4.5 to 6. Pseudo second order and Langmuir

adsorption isotherm was suited well to process. Thermodynamics parameters

indicated the process is exothermic in nature.

Barel et al [8] investigated the efficiency of treated bauxite to remove chromium

(VI) from a synthetic solution. The percentage of Cr (VI) was increased from 60.7

to 88.7% as biosorbent dosage was increased from 20 to 100 g/L. It was observed

that the percentage decreased with the increase of biosorbate concentration

whereas the reverse trend was observed in case of uptake. At pH 3.8, the

percentage of Cr (VI) was found to be maximum. The equilibrium was attained at

less than 10 min, for higher biosorbate concentration, while it was 60 min for low

biosorbate concentrations. The treated bauxite (1 g/25 mL) was found to be

capable of removing 98% chromium (VI) from solution having concentration 10

mg/L. The optimum temperature for chromium (VI) biosorption was found to be

46oC. The Gibbs free energy change (Go) and enthalpy (H) was found to be

3.26 kJ/mol and 553.32 J/mol. A pseudo second order model exactly fitted the

process. Physical structure were analysed using XRD, SEM and FTIR.

The removal of chromium and toxic ions present in mine drainage by thermally

treated Ecodermis of Opuntia was studies by Barrera et al [9]. When 100 mg was

16

used, maximum Cr (VI) biosorption was found to be 77 %, whereas that of Cr

(III) removal was 99 %. The Cr (III) and Cr (VI) uptake was maximum at pH =

4.0. The sorbent material was characterized using SEM, energy dispersive X-ray

spectroscopy, infrared spectroscopy, thermo gravimetric analysis before and after

adsorption. Experimental data were described by the Langmuir model. SEM

analysis indicated that the chromium adsorption took place on the surface of the

control biomass. EDX analysis confirmed the metal presence in the sorbent

material after contact with the solutions.

The comparative study of biosorption properties of the two types of Turkish fly

ashes (Afsin-Elbistan and Seyitomer) for chromium (VI) and cadmium (II) was

performed by Bayat [10]. The equilibrium attained for chromium (VI) and

cadmium (II) was 2 hours, for both the fly ashes. Optimum pH for Cr (VI) was 4

and 3 for Afsin-Elbistan and Seyitomer ashes respectively. The removal of Cr

(VI) by Afsin-Elbistan and Seyitomer fly ashes decreased from 50 to 25.46 and

56.45 to 30.91% respectively, by increasing the Cr (VI) concentration from 1 to

55 mg/L. Both Langmuir and Freundlich isotherms did not fit well to equilibrium

data.

Bhattacharya et al [11] studied batch process fro biosorption of Cr (VI) using

clarified sludge, rice husk ash, activated alumina, fuller’s earth, fly ash, saw dust

and neem bark. The optimum pH was found to be 2–3. Equilibrium was found to

be 2 h for clarified sludge and rice husk ash and 3 h for other biosorbents. Both

Langmuir and Freundlich isotherm model fitted well with the experimental data.

The maximum and minimum biosorption capacity was obtained for clarified

sludge (26.31 mg/g) and neem bark (19.60 mg/g) respectively. Thermodynamic

17

studies indicated the process is endothermic and spontaneous in nature. The

clarified sludge was found to be the most effective, for which the removal

efficiency reached to 99.8% of Cr (VI) at 30±2oC.

Blazquez et al [12] studied the effect of pH on biosorption of Cr (III) and Cr (VI)

with olive stone. At pH between 4 and 6, maximum percentage removal of Cr (III)

was found to be 90 %. More than 80 % of Cr (VI) removal was found at pH 2.

Results obtained from mixtures of Cr (III)/Cr (VI) (i.e., 5/15, 10/10 and 15/5

mg/L) indicated that Cr (VI) remained increases and Cr (III) decreases as pH

increases. Characterization of native, Cr (III) and Cr (VI) were analysed by FTIR

spectroscopy.

The use of activated rice husk (ARH) and activated alumina (AA) for the

biosorption of chromium (VI) from synthetic solutions were studied by Bishnoi et

al [13]. The maximum removal was found to be 88.88% and 80.86% by 0.3 and

1.0 mm of ARH, respectively at pH 2, whereas for AA it was 91.09% at pH 4.

Optimum dosage was found to be 10 g/L and 6 g/L for ARH and AA respectively.

The removal was 94.86% with ARH (0.3 mm), 85.02 with ARH (1.0 mm) and

97.44% with AA in 90 minutes. The biosorption pattern followed the Freundlich

isotherm model and biosorption efficiency for different biosorbents was

AA>ARH (0.3 mm) >ARH (1.0 mm).

Chergui et al [14] studied biosorption of Cu2+, Zn2+ and Cr6+ from aqueous

solution by NaoH pretreated Streptomyces rimosus biomass. Equilibrium was

reached at 90, 120 and 150 min for Cu2+, Zn2+ and Cr6+ respectively. At pH 6,

maximum equilibrium uptake was found to be 30.5, 29.6 and 29 mg/g for Cu2+,

Zn2+ and Cr6+ respectively. Optimum stirring speed was 250 rpm for all metal

18

ions. Both Freundlich and Langmuir isotherms were poorly fitted to the

experimental data. Maximum uptake was 30, 27.4 and 26.7 mg/g for Cu2+, Zn2+

and Cr6+ at concentration of 100mg/L.

Donmez et al [15] studied biosorption of copper(II), nickel(II) and chromium(VI)

on Chlorella vulgaris, Scenedesmus obliquus and Synechocustis sp. Optimum pH

values of Cu (II), Ni (II) and Cr (VI) were found to be 5.0, 4.5 and 2.0

respectively for all three algae. At Cr (VI) concentration of 250mg/L, the

maximum uptake was found as 33.8, 30.2 and 39.0 mg/g for C. vulgaris, S.

obliquus and S. sp. respectively. Cr (VI) uptake was 28.5, 21.4 and 31.0 mg/L for

C. vulgaris, S. obliquus and S. sp. respectively at 2.0 g/L dosage. Freundlich and

Langmuir isotherms fitted well for biosorption of Cu (II), Ni (II) and Cr (VI) on

all algal species.

Donmez and Aksu [16] reported the removal of chromium (VI) from saline

wastewaters by dunaliella species. The equilibrium was obtained at 72 hours with

53.6% and 45% total chromium (VI) removal with dunaliella species I and II

respectively. The highest uptake values were found at pH 2.0. At pH 2.0, the

removal of chromium (VI) was decreased from 37.7 to 13.4 mg/g for dunaliella I

and from 27.7 to 8.6 mg/g for dunaliella II with NaCl concentration upto 20%

(w/v). In the absence of salt, the loading capacity increased from 37.7 to 102.5

mg/g of Dunaliella sp. 1 and 27.7 to 85.5 mg/g of Dunaliella sp. 2, as metal

concentration was increased from 50 to 250 mg/L. Both Freundlich and Langmuir

adsorption models were suitable for describing the biosorption algae species. The

maximum uptake capacities for dunaliella species I and II were 189.8 and 153.6

19

mg/g for chromium (VI) in the absence of salt. The pseudo second order kinetic

model was also found to be in good agreement with the experimental results.

El-Sikaily et al [17] studied biosorption of chromium using green algae Ulva

lactuca and its activated carbon. Equilibrium was attained at 120 min for both

Ulva lactuca and its activated carbon. At pH 1.0, maximum removal was

observed. With increase of Cr (VI) concentration from 5 to 50 mg/L, Cr (VI)

removal decreased from 66 to 45 % for Ulva lactuca and when Cr (VI)

concentration increased from 5 to 250 mg/L, percentage removal decreased from

100 to 90 % for activated carbon. Langmuir isotherm model was found to describe

the data well. Maximum biosorption capacity was found to be 10.61 and 112.36

mg/g for Ulva lactuca and activated carbon. Pseudo second order kinetics was

well fitted to the equilibrium data.

Erdem et al [18] investigated the removal of Cr (VI) by using heat activated

bauxite. Maximum yield was found as 64.9% at dosage of 20 g/L, pH of 2.0, time

180 min and 20oC. Chromium (VI) efficiency was decreased from 61.3% to

27.8% with increasing the temperature from 20 to 45 oC. The maximum

chromium (VI) biosorption was found as 87.2% for 2.5 mg/L and 19.4% for 50

mg/L initial metal concentration. The activation energy was 10.27kJ/mol. The

Langmuir equation better fitted the experimental data. Thermodynamic

parameters Go, Ho and So were found to be 23.317 kJ/mol, -33.238 kJ/mol

and -0.034 kJ/gmol-K respectively. The negative value of So and Ho change

suggested no structural changes in biosorbate and biosorbent and process is

exothermic in nature.

20

Erol and Altun [19] studied Cr (VI) biosorption from aqueous solutions using

walnut (WNS), hazelnut (HNS) and almond (AS) shell. From the results of

kinetic studies equilibrium was reached with 100 min. Optimum pH for WNS,

HNS and AS were found to be 3.5, 3.5 and 3 respectively. Removal of Cr (VI) by

WNS, HNS and AS was 85.32, 88.46 and 55.0 % respectively at concentration of

0.5 mM. Sorption capacities were 8.01, 8.28 and 3.40 mg/g for WNS, HNS and

AS respectively.

Ertugay and Bayhan [20] studied biosorption of Cr (VI) from aqueous solutions

by biomass of mushroom species i.e., Agaricus bisporus. The highest metal

uptake yield was 92.4 % at pH 1.0, biosorpbent dosage of 10 g/L, speed of 150

rpm and temperature of 20oC. Langmuir isotherm fitted well than freundlich for

the biosorption data. Pseudo second order model fitted well to equilibrium data.

As temperature increased from 20 to 40oC, the uptake increased from 8.0 to 13.79

mg/g. Results from thermodynamics indicates that sorption is endothermic,

irreversible and spontaneous.

Gary et al [21] investigated the Cr (VI) biosorption from aqueous solutions on to

formaldehyde (SD) activated carbon (ACR) and sulfuric acid treated sawdust

(SDC) of Indian Rosewood, a timber industry waste. At pH of 3.0, maximum Cr

(VI) removal was found to be 99.7, 86.6 and 62.2 % for ACR, SDC and SD

respectively. The equilibrium reached quickly within 15, 60 and 180 min for

ACR, SDC and SD. Chromium (VI) removal by ACR was 100 % at all

concentrations. The biosorption removal was increased from 65.4 to 100 % and

50.7 to 92.2 %, as the SDC ans SD dosage was increased from 0.2 to 1.0 g/100

21

mL, while ACR had 100 % biosorption at all doses. The biosorption followed first

order Lagergren equation.

Gokhale et al [22] studied chromium biosorption on fresh and spent algal biomass

of Spirulina platensis and Chlorella vulgaris. The optimum pH was found to be

1.5. At chromium concentration of 50mg/L, maximum biosorption yield was

found to be 84.54 and 81.82% for S. platensis and C. vulgaris respectively.

Almost complete removal of Cr (VI) was found at 2.4 g/L algal dosage for both

the species. Freundlich and Langmuir isotherms fitted well to equilibrium data.

The adsorption capacity was found to be 188.68 and 163.93 mg/g for S. platensis

and C. vulgaris respectively.

Gupta et al [23] studied on biosorption of chromium (VI) by green algae

Spirogyra species. Equilibrium was observed at 120 min. Optimum pH was found

to be 2.0. At algal dosage of 5 g/L and Cr (VI) concentration of 5 mg/L, maximum

removal was found to be 96 %. Sorption isotherms followed Langmuir model.

Maximum Cr (VI) biosorption was found to be 14.7 x 103 mg/metal/kg of dry

weight biomass, at pH 2.0.

Gupta and Ali [24] studied the removal of lead and chromium from wastewater

using bagasse fly ash, a sugar industry waste. The equilibrium time was found to

be 40 and 60 min for lead and chromium respectively. The maximum biosorption

for lead and chromium was attained at metal concentration of 40 and 20 mg/L

respectively. The maximum uptake of lead and chromium took place at pH 6.0

and 5.0, dosage of 10 g/L was sufficient for the maximum uptake of lead and

chromium The biosorption capacity was 1.8 mg/g at pH = 5.0, dosage of 10 g/L

and Cr (VI) concentration of 20 mg/L. The optimum temperature was 30oC. The

22

Go, Ho and So at 30oC was -1.46 KJ/ mol, 49.0 KJ/mol and 49.0 J/mol for

chromium respectively. The experimental data fitted well with Langmuir and

Freundlich isotherms. The removal of these two metal ions was achieved up to

95–96% by column operations at a flow rate of 0.5 mL/min.

The adsorption of Cr (VI) by activated neem leaves was investigated by Gupta

and Babu [25]. The parameters investigated in this study were biosorption dosage,

contact time, initial chromium (VI) concentration and pH. The maximum

biosorption of Cr (VI) was found to be at pH values between 1 and 3. The

optimum contact time for maximum removal was 60 h with removal of 80%. The

biosorption capacity dropped from 6.15 mg/g to 1.9 mg/g by increasing the

biosorbent dosage from 4 g/L to 24 g/L. Application of the Langmuir isotherm to

the systems yielded maximum biosorption capacity of 10.5 mg/g at solution

pH of 7.

Gupta and Rastogi [26] conducted batch experiments to determine the biosorption

of hexavalent chromium by raw and acid-treated green alga Oedogonium hatei. At

pH of 2.0, biomass dose of 0.8 g/L, contact time of 110 min, and temperature

318K the biosorption capacities from Langmiur model was found to be 31 and

35.2mg/g for raw and acid-treated green algae respectively. Both Langmuir and

Freundlich model fitted well to the experimental data. Kinetics is well followed by

pseudo-first order model. Thermodynamic constants Go, Ho and So were

found to be −21.345 kJ/mol, 2.639 kJ/mol and 0.078 kJ/mol K respectively at

30oC. The thermodynamic calculations indicated the feasibility, endothermic and

spontaneous nature. Physical and chemical properties were evaluated by FTIR and

BET analysis

23

Gupta and Rastogi [27] studied biosorption and desorption of Cr (VI) on Nostoc

muscorum biomass. Maximum biosorption of 93.02% was observed at pH 3.0.

Equilibrium was attained within 120 min. Optimum dosage was found to be 1.0

g/L. Both Langmuir and Freundlich isotherm models fitted to the equilibrium

data. The maximum capacity was 22.92 mg/g at 25oC and pH 3.0. First and

second order models were found to follow biosorption process. Thermodynamic

parameters results show that the system is endothermic, spontaneous and increases

the randomness at solid-solution interface. Surface area and functional groups

were characterized by BET and FTIR respectively.

Cr (VI) biosorption on micro algal isolate, Chorella miniata was investigated by

Han et al [28]. The biosorbed chromium (VI) was reduced to chromium (III) and

desorption studies indicated that chromium (III) occupied most of the biosorption

sites on the biomass. Complete Cr (VI) removal was obtained at 150 h. At the

initial pH of 1.0, biomass concentration of 2.0 g/L, nearly 100 % of chromium

(VI) was removed within 58 hours.The maximum capacity was obtained at an

initial pH =3.0. The FTIR confirmed the presence of amino group on the algal

biomass and carboxylate group.

Ilhan et al [29] studied the removal of chromium, lead and copper ions from

industrial wastewater using Staphyloccus Saprophyticus. The highest biosorption

of 44 % Cr (VI) was obtained at pH = 2.0, at 27oC and at initial concentration of

193.66 mg/L. The equilibrium time was 120 min. While in the individual

solutions, the biosorption yield of the metals by S.Saprophyticus was 100%,

24.2% and 14.5% for Pb (II), Cr (VI) and Cu (II) respectively. In a mixed

solution, these were 100%, 25%, and 24% for Pb (II), Cr (VI) and Cu (II)

24

respectively. The usage of S.Saprophyticus as an biosorbent could be successful to

remove chromium element from the wastewater containing higher levels of Cr

(VI) ions.

Karthikeyan et al [30] investigated the biosorption of Cr (VI) onto Hevea

Brasilinesis (Rubber wood) sawdust activated carbon in a batch system. Cr (VI)

removal was maximum at pH = 2.0. Equilibrium was attained in 300 min.With

increase in concentration from 50 to 200 mg/L, the amount biosorbed was

increased from 33.51 to 42.64 mg/g. With increase in temperature from 293 to 323

K, the biosorption capacity was increased from 20.78 to 63.99 mg/g. Pseudo

second-order kinetics and Langmuir isotherm model fitted well to thw

experimental data. Thermodynamics results stated that the process is endothermic,

feasible and disorderliness of the biosorpiotn at solid-liquid interface.

Khambhaty et al [31] studied on biosorption of hexavalent chromium by dead

fungal biomass of marine Aspergillus niger. Maximum uptake was found to be

117.33 mg/g at pH 1.0, chromium concentration of 400 mg/L at 50oC. Langmuir

model and pseudo-second order fits the equilibrium and kinetic data respectively.

The results from thermodynamics study indicate that process is endothermic and

show randomness at solid/liquid interface during sorption.

Kiran et al [32] investigated the biosorption of chromium (VI) by native isolate of

Lyngbea putealis (HH-15) in the presence of salts. Maximum biosorption

(93.02%) was obtained at pH = 3.0. The optimum contact time was 120 min. As

the initial Cr (VI) concentration was varied from 10 to 50 mg/L in the absence of

salts, the biosorption capacity was increased from 8.0 to 48.0 mg/g, same pattern

was observed for salt combination. As salt concentration increased from 0 to 0.2%

25

at 20 mg/L, uptake decreased slightly from 18.0 to 17.0 mg/g. Maximum

biosorption capacity was found to be 113.6 mg/g in the absence of salts. The

experimental data fitted well with Langmuir and Freundlich isotherms models for

0.2% salt concentration. The pseudo second order equation fitted well with

experimental data

Kumar et al [33] studied biosorption of Cr (VI) from aqueous solution and

electroplating wastewater using Aspergillus niger, Aspergillus sydoni and

Penicillium janthinellum. Maximum removal of Cr (VI) was found to be 88.88 ±

2.04 %, 80.86 ± 2.24 % and 78.53 ± 2.28 % by A. niger, A. sydoni and P.

janthinellum respectively at pH 2.0. The removal of Cr (VI) was found to be 91.03

± 2.27 % with A. niger at dosage 0.6/50mL, 87.95 ± 1.64 % and 86.61 ± 1.62 %

with A. sydoni and P. janthinellum respectively at 0.8g/50mL. Maximum removal

was obtained at 30 mg/L. Equilibrium time was 60 min for all biosorbents. Both

Langmuir and Freundlich model fitted well for equilibrium data. Removal of Cr

(VI) from electroplating wastewater was observed less than from synthetic

solution.

Batch and continous experiments were conducted by Lakshmanraj et al [34] to

study chromium biosorption from aqueous solutions using boiled mucilaginous

seeds of Ocimum americanum. Toxic hexavalent chromium was reduced to less

toxic Cr (III) and reduced Cr (III) was biosorbed with the mucilage of the seeds.

Equilibrium time was reached within 180 min. The optimum chromium reduction

takes place at the pH range 1–1.5. With the increase in Cr (III) concentration, Cr

(III) adsorbed by seeds also increased. Biosorption data fitted well with Langmiur

isotherm and biosorption capacity obtained was 32 mg/g. The column study was

26

also carried out at the flow rate of 27 mL/h and initial Cr (VI) concentration 25

mg/L. 80 % of Cr (VI) reduced to Cr (III) and 56.25 % of initial chromium was

biosorbed by the seeds.

Loukidou et al [35] studied the biosorption of Cr (VI) from aqueous solutions, on

to aeromonas caviae particles. Optimu pH was found to be 2.5. The maximum

biosorption capacity was found to be in the range of 69.95 to 284.44 mg/g.

biosorption capacity increased from 124.46 to 169.10 mg/g, as temperature

increased from 20 to 60oC. At pH of 2.5, dosage of 1 g/L, concentration of 5-200

mg/L and temperature of 20oC, maximum capacity was found to be 124.46

mg/g.The equilibrium data fitted well by Langmuir isotherm than Freundlich

isotherm. Pseudo second order fitted experimental data.

Malkoc et al [36] had carried out batch and column experiments on Cr (VI)

biosorption from an aqueous solution using the waste pomace of olive oil factory

(WPOOF). Maximum biosorption occurred at pH 2.0. With increase of Cr (VI)

concentration from 50 to 200 mg/L and temperature from 25 to 60oC, uptake

capacities increased from 6.1 to 12.15 mg/g and 13.95 to 18.69 mg/g respectively.

Thermodynamic parameters state that the system is endothermic and spontaneous

in nature. Langmuir isotherm model fitted well to experimental data. For

continous syatem, the data is well fitted by Adams-Bohart model. Characterization

of WPOOF was investigated by FTIR and SEM.

Maria et al [37] studied on Cr (VI) biosorption by Aeromonas caviae. Optimum

pH value was obtained as 2.5. Maximum biosorption took place within first 30

min. Maximum capacity was obtained as 284.44 mg/g at 0.5 g/L and temperature

of 20oC. When the temperature increased increased from 20 to 60oC, biosorption

27

capacity increased from 124.46 to 169.10 mg/g. Langmuir model fitted a little

better than Freundlich model for equilibrium data. Pseudo second order fitted well

than pseudo first order from kinetic data.

Melo and D’Souza [38] studied the removal of chromium by mucaliginous seeds

of Ocimum basilicum. Maximum biosorption was observed at pH of 1.5.

Langmuir isotherm fitted well to the experimental data and maximum uptake was

found to be 205 mg/g. Cr (VI) uptake was found to be not affected by the presence

of Cu+2, Cd+2, Co+2 and Na+. In packed bed, when 0.4 L of solution was per-fused,

nearly 100% uptake was observed.

The studies on removal of chromium (VI) ions from aqueous solutions were

carried out by Mor et al [39] using activated alumina (AA) and activated charcoal

(AC). For AA and AC, maximum biosorption was observed at pH 4 and 2

respectively. At temperature 25 and 40oC, maximum biosorption for AA and AC

was observed Equilibrium time attained was 120 and 90 min for AA and AC

respectively. At Cr (VI) concentration of 10-100 mg/L, removal ranged from 99.8

to 76.94 % and 99 % for AA and AC respectively. Both Freundlich and Langnuir

isotherms fitted well to the experimental data.

Moussavi et al [40] investigated Pistachio Hull Powder (PHP) for removal of Cr

(VI) from water. Maximum biosorption capacity of 116.3 mg/g was attained at pH

2. Over 99% removal was attained from Cr (VI) concentration of 50-200 mg/L at

a pH of 2 and PHP dosage of 5g/L after 60 min of equilibrium time. Langmuir

model and pseudo-second order fits the equilibrium and kinetic data respectively.

Thermodynamic results indicated that biosorption is endothermic and

28

chemisorption occurred under the experimental conditions. Surface morphology,

specific surface area, pore volume and functional groups were characterized by

SEM, Nitrogen Adsorption Technique and FTIR respectively.

Murphy et al [41] studied chromium biosorption performance by Fucas

vesiculosus and Fucas spiralis (brown), Ulva spp. and Ulva lactuca, Palmaria

palmate and Polysiphonia lanose (red) algal biomass. Optimum pH was found to

be 2 for Cr (VI). Equibrium time for U. spp., U. lactuca and P. palmate was 120

min and F. vesiculosus, F.spiralis and P. lanose was 180 min. At lower

concentration (0.09 mM) removal efficiency was high for P. palmate (91 %) and

low for U. spp. (45 %). Maximum chromium capacity was found to be

0.88mmol/g for P. lanose. Characterization of the biomass is analysed by FTIR

spectroscopy.

Biosorpiton of chromium (VI) on Thuja orientalis were investigated by Oguz

[42]. To remove considerable amount of Cr (VI), contact time of 20 min is

sufficient at 315 and 333 K temperature. Maximum removal of Cr (VI) was

obtained at speed of 480 rpm. At pH 1.5, highest removal was attained. Freundlich

and D-R isotherm models fitted well to biosorption equilibrium. Pseudo second

order kinetics was well fitted to the sorption data. Activation energy was found to

be 11.15 kJ/mol. Results from thermodynamics show that the process is

endothermic and favourable at higher temperatures.

Removal of chromium and nickel from aqueous solutions using raw rice bran was

investigated by Oliverira et al [43]. Within 60-90 min, maximum biosorption i.e.,

60, 40 and 40 % was attained for Cr (III), Cr (VI) and Ni (II) respectively.

Maximum removal for Cr (III) and Ni (II) was observed at pH around 5-6 and for

29

Cr (VI) it was aound 1.5-2.0. For both nickel and chromium, Freundlich isotherm

model fitted well to the obtained data. Pseudo second order kinetics was well

fitted to the sorption data. Experimental data also showed that intraparticle

diffusion is significant in sorption rate determination. Thermodynamic results

state that Cr (VI) and Ni (II) sorption indicates unfavourablel sorption.

Ozdemir et al [44] reported the biosorption of chromium (VI), cadmium (II) and

copper (II) by Pantoea sp. TEM 18. Equilibrium was attained at 150 min.

Optimum pH for Cr (VI), Cd (II) and Cu (II) was found to be 3.0, 6.0 and 5.0

respectively. As Cr (VI) concentration increased from 28.9 to 245.2 mg/L

approxiamately, loading caoacity increased from 7.81 to 53.8 mg/g. Both

Langmuir and Freundlich models were well suitable for describing Cr (VI), Cd

(II) and Cu (II) biosorption. Langmuir parameters indicated that maximum

biosorption capacity was observed as 204.1 mg/g for Cr (VI).

Ozdemir et al [45] investigated the removal of chromium, cadmium and copper

metals applying a dead exopolysaccharide producing bacterium, Ochrobactrum

anthropi, isolated from activated sludge. . Equilibrium agitation time was 2 h.

Optimum pH values of Cr (VI), Cd (II) and Cu (II) were observed as 2.0, 8.0 and

3.0. As Cr (VI) concentration was varied from 30 to 280 mg/L, loading capacity

was increased from 6.4 to 57.8 mg/g. Both Langmuir and Freundlich models were

well suitable for describing Cr (VI), Cd (II) and Cu (II) biosorption. Langmuir

parameters indicated that maximum biosorption capacity was observed as 86.2

mg/g for Cr (VI).

Quintelas et al [46] studied the ability of Bacillus coagulas biofilm supported on

granular activated carbon (GAC) in batch and continous system. In batch process,

30

amount of Cr (VI) biosorbed increased from 38.87 to 784.90 mg/g, while

percentage removal decreased from 46.86 to 17.15 %, when initial Cr (VI)

concentration increased from 50 to 1000 mg/L. Toth model fitted well to

equilibrium data. Maximum capacity was found to be 19.44 mg/g from Langmuir

isotherm. Surface morphology and functional groups were characterized by SEM

and FTIR respectively. For column studies, uptake values were found to be 1.50,

1.98 and 5.34 mg/g for initial concentration of 10, 50 and 100 mg/L respectively.

Adams-Bohart and Wolborska models were found suitable for describing dynamic

behavior of column.

Radojka and Marina [47] conducted batch experiments for biosorption of Cr (VI)

and Cu (II) by waste tea fungal biomass. The optimum pH for Cr (VI) and Cu (II)

was found to be 2.0 and 4.0 respectively. Equilibrium time was 60 and 120 min

for Cr (VI) and Cu (II). It was observed that as biomass dosage increased,

biosorption efficiency increased. Freundlich and BET isotherms fitted well to

equilibrium data for Cr (VI) and Cu (II). The sorption kinetics of Cr (VI) and Cu

(II) followed first order rate law and Elovich model.

Rifaqat and Rehman [48] studied both batch and continous syatem for biosorption

of chromium on fruits of Ficus glomerata. At pH 2.0, maximum biosorption

occurred. For initial concentration of 10, 20, 50, 80 and 100 mg/L, biosorption

capacity was found to be 0.63, 1.31, 3.5, 5.4 and 6.7 mg/g respectively. As dosage

increased from 0.2 to 1.0g, percentage biosorption increased from 74 to 98%.

Thermodynamic properties indicates that the process in endothermic, spontaneous

and chemical in nature. Langmuir isotherm model is better fitted than Freundlich

model. Pseudo second order rate equation is followed by the syatem. Maximum

31

biosorption capacity was found to be 46.73 mg/g. in column studies, the

breakthrough and exhaustive capacity were found to be 5 and 23.1 mg/g

respectively. Surface morphology and functional groups were analysied by SEM

and FTIR respectively.

The chromium (VI) biosorption by Agave lechuguilla biomass was studied by

Romero-Gonzalez et al [49]. Optimum pH was obtained at pH = 2.0. Equilibrium

data fitted well with the Freundlich model. Thermodynamic parameters Go, Ho

and So were found to be -0.1288 kJ/mol, 13.46 kJ/mol and 47.88 J/mol-K

respectively at 10oC. Results from thermodynamics state that the process is

endothermic, spontanous and randomness in system. The equilibrium data fitted

well with Freundlich resulting in the maximum biosorption capacity of 12 mg/g.

The parameters of Dubinin-Radushkevick equation indicated that the sorption

mainly proceeded through binding surface functional groups.

Sahin and Ozturk [50] studied Cr (VI) biosorption on dried vegetative cell and

spore crystal mixture of Bacillus thuringiensis. Batch experiments were done as a

function of pH, initial metal ion concentration and temperature. Equlibrium time

was achieved with in 15 min. Optimum pH and temperature was determined as 2

and 25o C for both of the spore– crystal mixture and the vegetative cell. When the

Cr (VI) concentration was increased from 25 to 250 mg/L, the loading capacity of

has increased from 14.3 to 54.7 mg/g and 20.6 to 61.5 mg/g for vegetative cell and

crystal mixture respectively. Maximum biosorption yield was found to be 38.3 %

and 59.3 % for for vegetative cell and crystal mixture respectively at 25oC. Both

Langmuir and Freundlich isotherms fitted well to biosorption data and showed

good agreement to Scatchard analysis.

32

Sari and Tuzen [51] studied on the biosorption of total chromium onto red algae

(Ceramium virgatum) biomass from aqueous solution as a function of pH, contact

time, biomass dosage and temperature. At pH 1.5, 90 min equilibrium time, 10

g/L biomass dosage and 20 ◦C temperature, the biosorption capacity of C.

virgatum for total chromium was found to be 26.5 mg/g. Langmuir and pseudo-

second order model fitted well for biosorption equilibrium. Thermodynamic

parameters Go, Ho and So were found to be −16.1kJ/mol, −24.9 kJ/mol and

−29.4 J/mol K respectively at 30oC. The thermodynamic results indicated that the

process is feasible, exothermic and spontaneous in nature. To obtain the nature

between the functional groups of C. virgatum and the metal ions, FTIR analysis

was taken.

The biosorption of chromium (VI) from industrial waste by using Eucalyptus bark

was investigated by Sarin and Pant [52]. At pH 2, maximum percentage removal

i.e., 99 % was observed. Equilibrium contact time was found to be 3 h. Freundlich

isotherm was well fitted to biosorption data. Biosorption was found to follow first

order Lagergren kinetics. At 250 mg/L Cr (VI) concentration, biosorption capacity

was found to be 45 mg/g. The Go for chromium (VI) was -1.8789 kJ/ mol and

indicates the feasibility of biosorbent and spontaneity of biosorption.

Selvaraj et al [53] conducted batch experiments for the removal of hexavalent

chromium from aqueous and industrial effluent using distillery sludge.

Equilibrium was attained at 105 min. At pH 3, maximum biosorpion capacity of

93 % was observed. As Cr (VI) concentration increased from 10 to 40 mg/L,

percentage removal decreased from 93 to 64 %. Lanmuir and Freundlich isotherm

33

models fitted to the sorption data. Langmuir biosorption capacity was founs to be

5.7 mg/g. Desorption studies indicates that the removal of 82 % was possible.

Shaik et al [54] studied on Cr (VI) biosorption of marine brown algae Cystoseira

indica. C. indica was chemically modified by cross linked epicchlorohydrin (CB1,

CB2), oxidisized by KMnO4 (CB3) and washed by distilled water (RB). Highest

amount of Cr (VI) was found to be 22.7, 24.2, 20.1 and 17.8 mg/g for CB1, CB2,

CB3 and RB respectively at pH 3.0, chromium concentration 30 mg/L, dosage of

1.5 g/L and equilibrium time of 2 hrs. From Langmuir isotherm, maximum uptake

was obtained as 31.96, 34.74, 29.81 and 26.03 mg/g for CB1, CB2, CB3 and RB

respectively. D-R isotherm fitted well to equilibrium data. Surface area and

functional groups were characterized by BET and FTIR respectively.

Sharma et al [55] investigated the biosorption of chromium (VI) from water and

waste water by riverbed sand. At pH 2.5, lower Cr (VI) concentration of 1.0 x 10-5

M and temperature of 25oC, maximum removal was observed to be 74.3 %. At

smaller particle size of 100 µm of biosorbent, higher removal was found.

Thermodynamic parameters Go, Ho and So were found to be -0.81 kcal/mol, -

17.21 kcal/mol and 56.94 cal/mol-K respectively at 25oC, indicates that the

sorption is exothermic, spontaneous and confirm the possibility of favourable

biosorption.

Srividya and Mohanty [56] studied on biosorption of chromium from aqueous

solutions by Catla catla Scales. The percentage removal of Cr (VI) increased from

35.06 to 60.89 % when the dosage was increased from 0.05 to 0.4 g. optimum

conditions were found to be 1.0 pH, 0.05 g/L of biomass dosage, 200 rpm speed

and 180 min equilibrium time. Freundlich model and pseudo-second order fits the

34

equilibrium and kinetic data respectively. Surface morphology and functional

groups were characterized by SEM and FTIR respectively.

Sudha and Emilia [57] studied biosorption of Cr (VI) from aqueous solution by

Rhizopus nigricans. Optimum pH, biomass dosage, agitation speed and

temperature were found to be 2.0, 0.5% (w/v), 120 rpm and 45oC respectively.

Maximum removal was obtained after 8 h. Maximum removal of 99.2% was

obtained for smaller particle size of 90µm. At lower Cr (VI) concentration, higher

biosorption percentage was noted. Both Langmuir and Freundlich isotherms fitted

well to biosorption data.

Suksabye et al [58] studied biosorption of hexavalent chromium from

electroplating wastewater by coir pith.The equilibrium was attained at 18 h of

contact time. Maximum removal of 99% was observed at pH 2.0. The optimum

dosage for chromium (VI) sorption was at 20 g/L. The biosorption capacity of

chromium (VI) was increased from 138 to 317 mg/g with the increase of

temperature from 15oC to 60oC. The change in enthalpy (Ho) was found to be

33.39 KJ/mol and indicates that the sorption is endothermic in nature. Surface

morphology, surface area and functional groups of biosorbent were analysied by

SEM, BET and FTIR.

The biosorption of chromium (VI) by Mucor heimalis micro organism was

investigated by Tewari et al [59]. At pH 2.0, maximum biosorption was observed

to be 30.1 mg/g. Withe the increase in Cr (VI) concentration from 10 to 600 mg/L,

the uptake capacity was increased from 5.6 to 41.8 mg/g at 27oC. The equilibrium

was attained at 4 h. Langmuir isotherm was well fitted to biosorption data.

Biosorption was found to follow pseudo second order kinetics. With the increase

35

of temperature from 27 to 50oC, the maximum loading capacity increased from

47.5 to 53.5 mg/g. Results from thermodynamic parameters indicates that the

sorption is endothermic, spontaneous and increasing randomness at solid/liquid

interface.

Tunali et al [60] studied biosorption of chromium (VI) from aqueous solutions by

live and prepared Neurospora crassa fungal biomass in the batch mode. The

maximum biosorption of chromium (VI) was obtained at pH = 1.0 with an initial

chromium (VI) concentration of 250 mg/L. The equilibrium contact time was 90

min. The maximum uptake obtained at 250 mg/L Cr (VI) concentration was 9.15

mg/g. Maximum loading capacity was found to be 9.97 ± 1.32 mg/g at biomass

dosage of 0.3 g. Characterizsation of biosorbent was analysied by FTIR, SEM,

and EDAX.

Ucun et al [61] have studied Cr (VI) biosorption from aqueous solution by cone

biomass of Pinus sylvestris. The study was done with variation in the parameters

of pH, initial metal ion concentration and agitation speed. Equlibrium time was

reached in 2 hrs. Highest efficiency was obtained at pH 1.0. As Cr (VI)

concentration increased from 50 to 300 mg/L, biosorption removal decreased from

100 to 67.26 %. Maximum Cr (VI) was obtained at 150 rpm.

Vinod et al [62] studied the parameters (pH, contact time, initial metal ion and

biosorbent concentrations) effecting biosorption of nickel and total chromium

from aqueous solution by gum kondagogu (Cochlospermum gossypium). The

maximum biosorption capacity was found to be 129.8 mg/g for total chromium at

pH 2.0±0.1. For both nickel and total chromium, equilibrium was reached after

120 min. The % metal biosorption increased from 58.9±1.54 to 87.5±3.05% for

36

total chromium. However, the adsorption capacity decreased from 58.9±1.54 to

7.5±0.49mg/g for total chromium, when gum kondagogu concentration was

increased from 1000 to 5000mg/L. FTIR, SEM-EDXA and XPS analysis were

used to evaluate the binding characteristics of gum kondagogu with metals.

Langmuir and pseudo-second order model provides the best correlation for the

experimental data.

Verma et al [63] studied the biosorption characteristics of hexavalent chromium

using tamarind hull. Maximum removal of 99 % was observed at pH 1.0. Cr (VI)

removal decreased with increase in Cr (VI) concentration and increases with

increase in biosorbent dosage. Maximum capacity was found to be 60 mg/g at

10oC, which increased to 81 mg/g at 50oC. Results from thermodynamic

parameters indicate that the sorption is endothermic, spontaneous and increasing

randomness at solid/liquid interface. Freundlich, Redlich-Peterson and Fritz-

Schlunder isotherm models are in good agreement to the equilibrium data. Pseudo

fisrt order kinetics followed sorption data.

Wang et al [64] studied biosorption of Cr (VI) from aqueous solution by walnut

hull. Maximum removal (97.3%) of Cr (VI) was obtained at pH 1.0. With the

increase of Cr (VI) concentration from 240 to 480 mg/L, equilibrium capacity

increased from 59.2 to 90.8 mg/g. With the increase of biosorbent dosage, the

removal efficiency increases but metal uptake decreases. The first order, modified

Freundlich, intraparticle diffusion and Elovich models were found to follow

biosorption process. Maximum uptake capacity was found to be 98.13 mg/g.

Thermodynamic parameters results show that the system is endothermic, increases

the randomness and feasible.

37

Cadmium

Agarwal and Sahu [65] studied the biosorption of cadmium onto manganese

nodule residue. The optimum pH was found to be 5.5 with cadmium removal of

about 98.8 %. For the sufficient cadmium removal, equilibrium time was

maintained at 4 h. With the increase of cadmium concentration from 200 to

500mg/L, percentage removal of cadmium decreased from 99.75 to 85 %

respectively. With the increase of MNR dosage from 0.5 to 3 g, percentage

removal of cadmium increased from 56.25 to 99.9 % respectively. Biosorption

isotherm both fitted Freundlich and Langmiur isotherm and maximum biosorption

capacity of Cd (II) was found to 19.8 mg/g. Experimental data was better fitted to

pseudo second order than pseudo first order and intra particle diffusion.

Thermodynamic parameters indicated that the system is spontaneous and

endothermic in nature. Surface morphology was characterized by SEM.

Aksu [66] studied the cadmium biosorption from aqueous solution from dried

green algae C.vulgaris. Equilibrium time was found to be 120 min. At pH 4.0,

maximum uptake was found as 62.3 mg/g. The optimum temperature was

determines as 20oC. As initial cadmium concentration increased from 24.9 to

198.6 mg/L, the loading capacity increased from 22.0 to 85.3 mg/g and percentage

removal decreased from 89.2 to 42.9 %. As the temperature rises from 20 to 50oC,

the percentage removal decreased from 89.2 to 47.7 %. Equilibrium data fitted

well to both Freundlich and Langmuir isotherms models with maximum capacity

of 111.1 mg/g. Biosorption kinetics followed pseudo-second-order model.

Anayurt et al [67] studied the Pb (II) and Cd (II) biosorption from aqueous

solution onto Lactarius scrobiculatus-macrofungas. At pH 5.5, maximum

38

biosorption for Pb (II) and Cd (II) ions was found to be 98 % and 96 %

respectively. Equilibrium time was observed to be 60 min. Optimum biomass

dosage and temperature was selected as 4 g/L and 20oC respectively. Equilibrium

data was fitted to Langmuir model than Freundlich isotherm model for both

metals and maximum uptake capacity for Pb (II) and Cd (II) ions was found to be

56.2 and 53.1 mg/g respectively. The mean free energy from D-R model for Pb

(II) and Cd (II) ions was calculated as 10.4 and 9.6 kJ/mol respectively.

Biosorption kinetics followed pseudo-second-order model for both metals.

Thermodynamic parameters indicated that biosorption process is exothermic,

feasible and spontaneous in nature. Functional groups were analyzed by FTIR.

Areco and Afonso [68] studied the biosorption of cadmium (II), copper (II), lead

(II) and zinc (II) onto Gymnogongrus torulosus. Equilibrium period of 24 h was

selected for bioosorption experiments. Maximum uptakes were found at pH values

above 5.0. Among Langmuir, Freundlich, Dubinin-Radushkevich and Temkin

isotherms, equilibrium data obtained was better represented by Langmuir isotherm

model. Among pseudo-first order, pseudo second-order and intra-particle

diffusion, biosorption kinetics followed pseudo-second-order model. The

thermodynamic parameter indicated that the biosorption is exothermic,

irreversible and spontaneous in nature. All energy values obtained are higher than

8kJ/mol, implied that the metals were biosorbed chemically onto the biomass.

Morphological characterization of G. torulosus was evaluated by Scanning

Electron Microscope (SEM).

Barka et al [69] studied Cd (II) removal of aqueous solution by Scolymus

hispanicus L. As particle size decreased from 500 µm to 100 µm, Cd (II) uptake

increased from 23.23 to 36.96 mg/g. At pH 6.5, maximum biosorpion capacity

39

was observed. With increase of initial Cd (II) concentration, equilibrium uptake

also increased. With increase of biosorbent dosage from 1 to 6.0 g/L, Cd (II)

removal increased from 26.45 to 92.05 %. Cadmium biosorption is better

described by pseudo second order kinetics model. Langmuir isotherm model fitted

the experimental data with maximum uptake of 54.05 mg/g. Cd (II) removal did

not change significantly with raise in temperature. Functional groups of unloaded

and loaded S. hispanicus were analysed by FTIR.

Chakravarty et al [70] investigated the biosorption of Cd (II) ions from aqueous

solution by heartwood of Areca catechu (HPAC). Equilibrium time was attained

within 30 min. Maximum removal of cadmium was observed at pH 6.0. With the

increase in Cd (II) concentration from 10 to 70 mg/L, the percentage of removal

decreased from 98 to 72 %. At Cd (II) concentration of 20 mg/L, the optimum Cd

(II) removal was found to be 97 %. Optimum HPAC dosage was found to be 0.4

g. Biosorption kinetics followed pseudo-second-order rate equation. Equilibrium

biosorption followed Langmuir model better than Freundlich and D-R model.

Maximum biosorption capacity was found to be 10.66 mg/g with respect to

Langmuir isotherm. Functional groups and surface morphology of fresh and Cd

(II) loaded were characterized by FTIR and SEM respectively.

Chen et al [71] studied the biosorption of cadmium by byproduct of brown-rot

fungus Lentinus edodes a kind of agricultural waste. The maximum pH for

biosorption occurred at 6.0-7.0. As initial concentration decreased from 100, 50

and 20 mg/L, the cadmium uptake increased from 60.0, 32.1 and 14.25 mg/g

respectively. At biosorbent dosage of 1 g/L, maximum biosorption was occurred.

Equilibrium data was better fitted to Freundlich model than Langmuir and Temkin

40

model and maximum uptake of Cd (II) was found to be 5.58mmol/g. To reveal

ion-exchange mechanism between Cd (II) and functional groups during

biosorption, FTIR spectrum and energy-dispersive X-ray microanalyzer were

used.

Choi and Yeoung-Sang [72] studied cadmium biosorption on cost-effective four

types of sludge i.e., drinking water treatment plant sludge (DWS), landfill leachate

sludge (LWS), anaerobically digested sewage sludge (ADSS) and sewage sludge

(SS). Equilibrium time was attained at 4 h. In order to determine the most

effective sludge, all experiments were conducted at initial concentration ranging

from 0-5 mM and at pH 5.0. At equilibrium concentration of 3.29 mM, the

amount of cadmium biosorbed was found to be highest for SS with uptake of

0.38mmol/g. The cadmium capacities of DWS, LLS, and ADSS were found to be

0.13, 0.24 and 0.18 mmol/g respectively. Data obtained for DWS, LLS, and

ADSS did not fit to Langmuir adsorption model, but well fitted to SS with

correlation coefficient (R2) 0.996. Functional groups were analyzed by FTIR.

Cruz et al [73] investigated biosorption of cadmium ions from aqueous solution

onto dead Sargassum sp. biomass. Equilibrium was attained after 30 min.

Maximum biosorption capacity was attained for agitation time greater than 100

min, so 150 min was chosen for further experiments. Optimum pH was found to

be 3.0. With the increase of Cd (II) concentration from 25 to 1000 mg/L, the

biosorption capacity increased from 5.04 to 114 mg/g. Biosorption isotherm

followed Langmiur isotherm and maximum biosorption capacity of Cd (II) was

found to be 120 mg/g. Experimental data was better described by pseudo second

41

order model. Thermodynamic parameters indicated that the system is exothermic

and no change on entropy occurs.

Dang et al [74] investigated the biosorption of Cd (II) and Cu (II) ions on wheat

straw Triticum aestivum in aqueous solution. At equilibrium time of 3.5 h,

cadmium removal was found be 87 %. With the increase of pH from 4.0 to 7.0,

the equilibrium capacity increased about 130 and 60 % for Cd (II) and Cu (II)

respectively. As the initial metal concentration increases, the percentage removal

of metal ions increases and values of the electronegativity for Cd (II) and Cu (II)

are 1.69 and 1.90 respectively. When the temperature increased from 20 to 30oC,

the amount of Cd (II) removal increased slightly from 42 to 45 mg/L. Equilibrium

data fitted well to Langmuir model for both metals than Freundlich, Temkin and

D-R isotherms and maximum capacity was found to be 0.13 and 0.18 mmol/g for

Cd (II) and Cu (II) respectively. Biosorption of Cd (II) and Cu (II) was well

described by pseudo-second order kinetics.

Fan et al [75] investigated the cadmium (II), zinc (II) and lead (II) biosorption

onto Penicillium simplicissimum. Maximum biosorption capacities for Cd (II), Zn

(II) and Pb (II) were obtained at pH 4.0, 6.0 and 5.0 respectively. Equilibrium was

attained at 3 h for Cd (II), 4h for Zn (II) and Pb (II) respectively. At 200 mg/L for

Cd (II), 250 mg/L for Zn (II) and Pb (II), the maximum uptake capacities were

obtained as 52.50, 65.60 and 76.90 mg/g respectively. Equilibrium data obtained

was better represented by Langmuir isotherm and Redlich-Peterson models and

maximum biosorption capacities for Cd (II) derived from Langmuir and D-R

model were found to be 61.35 and 168.32 mg/g respectively. Biosorption kinetics

followed pseudo-second-order model rather than pseudo-first-order for Cd (II), Zn

42

(II) and Pb (II). Thermodynamic parameters indicated that biosorption of Cd (II),

Zn (II) and Pb (II) were endothermic and spontaneous in nature.

Gupta and Rastogi [76] studied cadmium (II) biosorption by nonliving algal

biomass Oedogonium sp. from aqueous phase. Maximum biosorption capacity

was found to be 88.2 mg/g at an algal dosage of 1.0 g/L in 55 min of contact time

with initial concentration of 200 mg/L and optimum pH of 5.0. With increase in

temperature from 25 to 45oC, biosorption of Cd (II) decreased from 88.9 to 80.4

mg/g. Biosorption of Cd (II) followed pseudo-second-order model. Equilibrium is

well described by Langmuir isotherm. Thermodynamic parameters indicate that

sorption is exothermic, spontaneous and increases randomness at the solid –

solution interface. By BET method, surface area was found to be 1.22 m2/g and

FTIR analysis, showed the presence of carboxyl, amino, amide and hydroxyl

groups.

Hai-Ping et al [77] investigated the biosorption of Cd (II) by Streptomyces sp. K33

and HL-12. Experiments were carried out at pH ≤ 6, to ensure no interference

from metal precipitation. As initial Cd (II) concentration increased from 1, 10 and

50 mg/L, metal uptake increased from 1.245, 12.15 and 33.41 mg/g for K 33 and

0.64, 7.15 and 17.45 mg/g for HL 12. Equilibrium data was best fitted to

Langmuir model and maximum biosorption capacity was found to be 39.222 mg/g

(0.349 mmol/g) and 49.02 mg/g (0.436mmol/g) for HL-12 and K33 respectively.

Biosorption kinetics followed pseudo second order model. There is no significant

change in biosorption capacities, as the temperature is increased and experimental

temperature was chosen to be 28oC. FTIR was used to characterize the interaction

between Cd (II) and K33 and HL-12.

43

Herrero et al [78] studied the cadmium binding by the dead red macroalga

Mastocarpus stellatus. Biosorption reaches over 90 % of total metal uptake in the

first 9 min. As Cd (II) concentration increases from 0.3, 1, 3 and 4 mmol/L,

percentage removal decreases from 45.4, 31.3, 29.1and 26.8 % respectively. With

the increase of temperature from 15, 25, 35 and 45oC, percentage removal

decreases from 31.5, 31.3, 26.4 and 18.1 % respectively. Biosorption kinetics

followed pseudo second order model. Equilibrium data was better fitted to

Langmuir model and Langmuir-Freundlich models. Maximum cadmium uptake

was found in the range between 0.54 and 0.59 mmol/g.

Jyh-Ping and Yung-Sheng [79] studied the cadmium biosorption on Sol-gel-

immobilized recombinant Escherichia coli in batch and continous systems.

Equilibrium was reached in 3 h. With the increase of cadmium concentration from

25 to 250 mg/L, the metal uptake increased from 31.5 to 80.2 mg/g. Equilibrium

data fitted well to Langmuir isotherm model and maximum uptake capacity was

found to be 79.9 mg/g at 25oC. Biosorption kinetics followed pseudo-second-order

model. Thermodynamic parameters indicated that biosorption process is

endothermic and confirms the randomness at solid-surface solution interface

during biosorption. Though the maximum capacity occurred at 25oC, temperature

did not affect significantly on biosorption of cadmium. For continuous system,

with the increase of flow rate, breakthrough time shortens and flatteners the curve.

For flow rate of 0.3 and 0.5cm3/min, the integrations of the effluent concentration

over elution volume up to saturation point gave overall biosorption capacities at

46.4 and 44.6 mg/g respectively.

44

Li et al [80] studied Cd (II) and Pb (II) ions biosorption by Phanerochaete

chryosporium, a filamentous fungas. At pH 4.5, the maximum metal uptake for Cd

(II) and Pb (II) was found to be 15.2 and 12.34 mg/g respectively. At initial

concentration of 50 mg/L, the maximum metal uptake for Cd (II) and Pb (II) was

found to be 15.2 and 12.34 mg/g respectively. When the pellet diameter was

between 1.58 and 2.03 mm, the maximum uptake of 15.2 mg/L was obtained.

When the temperature increased from 25 to 30oC, there is no significant effect on

Cd (II) uptake and Pb (II) uptake decreased monotonically, biosorbed quantity at

35oC was only half at 27oC. Biosorption data fitted Freundlich model well with

correlation coefficient 0.9856 and 0.9919 for Cd (II) and Pb (II) respectively.

Liu et al [81] studied the biosorption of marine brown algae Laminaria japonica

and was chemically modified by crosslinking with epichlorohydrin (EC1 and

EC2), oxidizing by potassium permanganate (PC), with glutaraldehyde (GA) and

only washed by distilled water (DW). Equilibrium was reached in less than 2 h.

The optimum percentage removal for all four metals was found for the pH range

of 4.3-6.5 for chemically modified and raw algae. The optimum s/l ratio is 3.0 g/L

in terms of cost efficiency. Pseudo first order kinetic model fits experimental data

compared to second order model. Equilibrium was well described by both

Langmuir and Redlich-Peterson isotherm models. Maximum Cd (II) capacities

were found to be 1.85, 1.42, 1.05, 0.67 and 0.93 mmol/g for EC1, EC2, PC, GA

and DW respectively. Maximum metal capacities were found to be 1.85, 1.78,

1.13 and 1.42mmol/g for Cd (II), Cu (II), Ni (II) and Zn (II) respectively.

Lodeiro et al [82] studied the ability to remove cadmium with brown seaweeds

i.e., Bifurcaria bifurcata, Saccorhiza polyschides, Ascophylloum nodosum,

45

Laminaria ochroleuca and Pelvetia caniculata. Equilibrium time for all aglae’s

was found to be 3 h. Maximum Cd (II) uptake was found to 95 mg/g for P.

caniculata. Biosorption process followed Langmuir isotherm for all aglae.

Cadmium biosorption is better described by pseudo second order kinetics model

for all aglae. The maximum uptake found to be inorder S. polyschides (95±3

mg/g) > A. nodosum (79±2 mg/g) > P. caniculata (75±2 mg/g) > B.bifurcate

(74±3 mg/g) > L. ochroleuca (64±3 mg/g).

Martinez et al [83] studied biosorption of lead (II) and cadmium (II) from aqueous

solution onto grape stalk waste a byproduct of wine production. Contact time of 2

h was chosen as equilibrium time. Maximum biosorption of Pb (II) and Cd (II)

was attained at pH 4.5 and 6.5 respectively. The reduction of Pb (II) and Cd (II)

biosorption was due to the presence of NaCl and NaClO4 in the solution.

Biosorption isotherm fitted Langmiur isotherm and maximum biosorption

capacity of Pb (II) and Cd (II) was found to be 0.241 and 0.248 mmol/g.

Functional groups and surface morphology were characterized by FTIR and SEM

respectively.

Mashitah et al [84] studied cadmium biosorption by immobilized cells of

Pycnoporus sanguineus from aqueous solution. At pH of 6, maximum cadmium

biosorption was obtained. With the increase of Cd (II) concentration from 50 to

300 mg/L, removal decreased from 79 to 37 %. Cadmium uptake decreased from

3.42 to 1.36 mg/g and increased from 2.75 to 3.27 mg/g, with the increase of

dosage from 1.0 to 6.0 g and temperature from 30 to 40oC respectively. Langmuir

isotherm model best fitted the experimental data followed by Redlich-Peterson

and Freundlich models. Cadmium biosorption is better described by pseudo first

46

order kinetics model followed by pseudo second order kinetics model and

intraparticle diffusion. Thermodynamic parameters indicated that the process is

spontaneous and endothermic in nature.

Mata et al [85] studied the biosorption of cadmium, lead and copper with brown

algae Fucus vesiculosus. Equilibrium was reached after 2 h. Equilibrium data

obtained was better represented by Langmuir isotherm model. The maximum

capacity sequence obtained from Langmuir isotherm was Cu > Pb ≈ Cd i.e., 1.66,

1.02 and 0.9626 mmol/g. Biosorption kinetics followed pseudo-second-order

model and did not fit for intraparticle diffusion model. Morphological

characterization and functional groups of F. vesiculosus was evaluated by SEM

and FTIR respectively.

Mathialagan and Viraraghavan [86] studied the cadmium biosorption by perlite

from aqueous solution in batch and continuous systems. At optimum pH of 6.0,

cadmium removal was found to be 55 %. Equilibrium was attained in 6 h.

Experimental data was better fitted to Ho’s pseudo second order. Biosorption

isotherm followed Freundlich isotherm model. The maximum cadmium removal

from batch studies was found to be 55 %. Column data was described by Thomas

model and biosorption capacity was found to be 0.42 mg/g.

Munagapati et al [87] studied the biosorption of Cu (II), Cd (II) and Pb (II) onto

Acacia Leucocephala bark powder from aqueous solution. The maximum

biosorption was observed at pH 6.0, 5.0 and 4.0 for Cu (II), Cd (II) and Pb (II)

respectively. Optimum biosorbent dosage of 0.6 g/0.1 L was found to be optimum.

At contact time of 180 min, maximum of 82.5 % of Cd (II) was removal, so

contact time of 180 min was found to be optimum. For all the metals, second

47

order kinetic model was best fitted. Equilibrium data was better fitted to Langmuir

model for all metals and maximum uptake of Cd (II) was found to be 166.7 mg/g.

Thermodynamic parameters indicated that the system is exothermic and

spontaneous in nature. Functional groups and surface morphology were

characterized by FTIR and SEM respectively.

Ozdemir et al [88] studied the removal of Cr (VI), Cd (II) and Cu (II) onto dead

exopolysaccharide producing Ochrobactrum anthropi isolated from activated

sludge. Optimum pH values of Cr (VI), Cd (II) and Cu (II) were found to be 2.0,

8.0 and 3.0 respectively. Equilibrium time for all metals was found to be 2 h. At

initial Cd (II) concentration of 100.6 mg/L, the maximum loading capacity was

found to be 28.5 mg/g. Both Langmuir and Freundlich biosorption models were

suitable for describing the biosorption of all metals. The maximum biosorption

capacities obtained from Langmuir parameters were found to be 86.2, 37.3 and

32.6 mg/g for Cr (VI), Cd (II) and Cu (II) respectively.

Ozdemir et al [89] studied the biosorption of chromium (VI), cadmium (II) and

copper (II) by Pantoea sp. TEM 18. Equilibrium time was found to be 15 min for

all three metals. The maximum capacity was obtained at pH 3.0, 6.0 and 5.0 for Cr

(VI), Cd (II) and Cu (II) respectively. At initial cadmium concentration of 95.8

mg/L, maximum loading capacity was found to be 52.0 mg/g. Freundlich and

Langmuir isotherms models were suitable for describing biosorption of chromium

(VI), cadmium (II) and copper (II). Langmuir parameters indicated that the

maximum biosorption capacity for Cr (VI), Cd (II) and Cu (II) was found to be

204.1, 58.1 and 31.3 mg/g respectively.

48

Ozdemir et al [90] studied the biosorption of Cd, Cu, Ni, Mn and Zn from aqueous

solutions by thermophilic bacteria i.e., Geobacillus toebii sub-species decanicus

(G1) and Geobacillus thermoleovorans sub-species stromboliensis (G2). The

optimum pH values for Cd, Cu, Ni, Zn and Mn in G1 were found to be 6.0, 4.0,

4.0, 5.0 and 6.0 respectively and 4.0, 4.0, 4.0, 4.0 and 5.0 for G2 respectively. The

optimum temperature of Cd for G1 and G2 was found to be 70oC. With the

increase of biosorbent dosage from 0.25 to 10 g/L, biosorption capacity decreased

sharply from 38.1 to 4.7 mg/g for G2 and from 30.3 to 4.4 mg/g for G1. Pseudo

second order kinetic model provide good correlation for biosorption of heavy

metals. Maximum Cd (II) capacities for G1 and G2 were found to be 29.2 and

39.8 mg/g respectively. Thermodynamic parameters indicated that the system is

endothermic and suggest an increase in randomness at the solid/solution interface

during the process. Characterizations of biomass were analyzed by FTIR.

Panda et al [91] investigated cadmium biosorption from aqueous solution on to

husk of Lathyrus sativus. The optimum pH was found to be 5.0–6.0. Equilibrium

was attained within 60 min. Temperature has no significant effect. Biosorption

isotherm fitted Langmiur isotherm and maximum biosorption capacity was found

to be 35 mg/g. Experimental data was better described by pseudo second order

model. Surface morphology was characterized by SEM.

Perez-Marin et al [92] investigated the biosorption of cadmium onto orange waste

from orange juice industry. Equilibrium was attained within 60 min. With the

increase of pH from 2 to 6, percentage removal increased from 8 to 98 %. The

optimum orange waste dosage was found to be 4 g/L. Biosorption isotherm was

best fitted to Sips model than Langmuir, Freundlich and Redlich-Peterson

49

isotherm model. The maximum uptake from Sips model was found to be 0.40,

0.41 and 0.43mmol/g at pH 4, 5 and 6 respectively. Experimental data was better

described by Elovich equation than pseudo first order, pseudo second order and

intra particle diffusion equation. Functional groups were characterized by FTIR.

Pino et al [93] studied the effective removal of cadmium by green coconut shell

powder. Optimum pH was found to be 7.0 and highest removal capacity for

cadmium was found to be 98 %. With the decrease of particle size of the coconut

shell powder, the removal of cadmium also decreased. Equilibrium data fitted well

to both Langmuir and Freundlich isotherm models and maximum capacity was

found to be 285.7 mg/g. Cadmium biosorption provides better correlation for

pseudo second order kinetics model. Morphological characterization of coconut

was evaluated by Scanning Electron Microscope (SEM).

Rangasayatorn et al [94] studied the cadmium biosorption by immobilized

Spirulina platensis TISTR 8217 on alginate gel and silica gel. Equilibrium was

attained at 45 min for both immobilized cells on alginate and silica gels and the

cadmium removal was higher than 95 % for both gels. For alginate immobilized

cells, highest biosorption was found to be 96.96 % at pH 6 and for silica

immobilized cells, biosorption was not affected at pH between 4 and 7. With

increase in temperature from 20, 26, 30 and 40oC, maximum biosorption was

found to be 96.20, 92.32, 94.72 and 94.88 mg/g for alginate immobilized cells and

95.48, 94.72, 92.96 and 92.68 mg/g for silica immobilized cells respectively.

From Langmuir isotherm, the maximum capacities for alginate and silica

immobilized cells were 70.92 and 36.63 mg/g respectively.

50

Rao et al [95] studied the biosorption of Cd (II) from aqueous solution onto

Fennel biomass (Foeniculum vulgari) – a medicinal herb. At pH 4.3, maximum

biosorption of 92 % was obtained. With the increase of Cd (II) concentration from

5, 25, 50 and 100 mg/L, the equilibrium uptake was increased from 0.49, 2.46, 4.9

and 9.3 mg/g respectively. With the increase of temperature from 30, 40 and 50oC,

maximum biosorption capacity was increased from 21, 24 and 30 mg/g

respectively. Biosorption isotherm followed Freundlich isotherm at 50oC.

Experimental data was better described by pseudo second order model.

Thermodynamic parameters indicated that the system is spontaneous, endothermic

and increased randomness at the solid/solute interface. Functional groups and

surface morphology were characterized by FTIR and SEM respectively.

Rathinam et al [96] studied cadmium biosorption from stimulated wastewaters

using Hypnea valentiae biomass. At pH of 6.0, maximum removal of 17 mg/g was

observed. With the increase of dosage from 4 to 8 g/L, biosorption capacity

decreased from 27.08 to 6.21 mg/g. As the initial concentration was varied from

25 to 500 mg/L, biosorpion capacity increased from 4.34 to 24.60 mg/g. At

temperature of 60oC, maximum biosorption of 23.14 mg/g has been obtained.

Cadmium biosorption is better described by pseudo first order kinetics model.

Biosorption process followed Langmuir isotherm equation. Thermodynamic

parameters indicated that the process is spontaneous and endothermic in nature.

Romera et al [97] studied biosorption of cadmium, nickel, zinc, copper and lead

on Codium vermilara, Spirogyra insignis, Asparagopsis armata, Chondrus

crispus, Fucas spiralis, Ascophyllum nodosum. Except for S. insignis, the

optimum pH for all algae was found to be 6. Irrespective of type of algae or metal,

51

the maximum sorption capacity was observed at biomass dosage of 0.5 g/L.

Experimental data was well fitted to Langmuir model in according to sorption

values: Pb > Cd ≥ Cu > Zn > Ni. Biosorption capacities for C. vermilara, S.

insignis, A. armata, Chondrus crispus, A. nodosum and F. spiralis were found to

be 21.8, 22.9, 32.3, 75.2, 114.9 and 87.7 respectively.

Saeed et al [98] studied the biosorption of Cu (II), Cd (II) and Zn (II) ions from

aqueous solution onto papaya wood. Equilibrium was attained within 60 min. At

pH 5.0, the maximum removal of Cu (II), Cd (II) and Zn (II) was found to be 97.3,

95.3 and 66.6 % respectively. The optimum biomass dosage was 5 g/L. The

maximum removal of Cu (II), Cd (II) and Zn (II) was found to be 97.8, 94.9 and

66.8 % at 10 mg/L of metal concentration with 5 g/L of papaya wood dosage and

contact time of 60 min. Biosorption isotherm fitted Langmiur isotherm and

maximum biosorption capacity of Cu (II), Cd (II) and Zn (II) was found to be

19.88, 17.22 and 13.45 mg/g respectively. Experimental data was better described

by pseudo second order model.

Sari and Tuzen [99] investigated the Pb (II) and Cd (II) biosorption from aqueous

solution onto Ulva lactuca-green algae. At pH 5.0, maximum biosorption for Pb

(II) and Cd (II) ions was found to be 95 % and 90 % respectively. Equilibrium

time was observed to be 60 min. Optimum biomass dosage and temperature was

selected as 20 g/L and 20oC respectively. Equilibrium data was fitted to Langmuir

model than Freundlich isotherm model for both metals and maximum uptake

capacity for Pb (II) and Cd (II) ions was found to be 34.7 and 29.2 mg/g

respectively. The mean free energy from D-R model for Pb (II) and Cd (II) ions

was calculated as 10.4 and 9.6 kJ/mol respectively. Biosorption kinetics followed

52

pseudo-second-order model for both metals. Thermodynamic parameters indicated

that biosorption process is exothermic, feasible and spontaneous in nature.

Sari and Tuzen [100] investigated biosorption of cadmium by red algae Ceramium

virgatum. At pH 5, maximum efficiency was found to be 96 %. Equilibrium time

was attained at 60 min. The optimum biosorbent dosage was found to be 10 g/L.

As temperature increases from 293 to 323 K, biosorption yield decreased from 97

to 87 %. Equilibrium data fitted well to Langmuir model than Freundlich

isotherm and maximum capacity was found to be 39.7 mg/g. From the D-R model,

the mean energy was obtained as 12.7 kJ/mol. Biosorption kinetics followed

pseudo-second-order model. Thermodynamic parameters indicated that

biosorption is exothermic, feasibility and spontaneous in nature. Functional

groups of unloaded and loaded C. virgatum were analysed by FTIR.

Sari et al [101] studied the characterization of Cd (II) and Cr (II) ions using

Hylocomium splendens biomass from aqueous solution. Equilibrium time was

found to be 60 min for both metals. At pH 5.0, the maximum biosorption was

found to be 98 and 99 % for Cd (II) and Cr (III) respectively. Optimum biomass

dosage was found to be 4 g/L. As temperature increased from 20 to 50oC,

biosorption percentage removal decreased from 97 to 82 % for Cd (II) and from

99 to 86 % fron Cr (III), so optimum temperature was selected as 20oC.

Biosorption kinetics followed pseudo second order model. Equilibrium data was

better fitted to Langmuir model and maximum biosorption capacity was found to

be 32.5 mg/g for Cd (II) and 42.1 mg/g for Cr (III). Thermodynamic parameters

showed that the system is exothermic, feasible and spontaneous in nature.

53

Sari and Tuzen [102] studied the biosorption of Cd (II) and Pb (II) ions using the

macrofungus Amanita rubescens biomass from aqueous solution. Equilibrium

time was found to be 30 min for both metals. At pH 5.0, the maximum biosorption

was found to be 97 and 98 % for Cd (II) and Pb (II) respectively. Optimum

biomass dosage was found to be 4 g/L. As temperature increased from 20 to 50oC,

biosorption percentage removal decreased from 95 to 86 % for Cd (II) and from

97 to 88 % from Pb (II), so optimum temperature was selected as 20oC.

Biosorption kinetics followed pseudo second order model. Equilibrium data was

better fitted to Langmuir model and maximum biosorption capacity was found to

be 27.3 mg/g for Cd (II) and 38.4 mg/g for Cr (III). Thermodynamic parameters

showed that the system is exothermic, feasible and spontaneous in nature. The

nature of cell-metal ions interactions was analysed by FTIR.

Say et al [103] studied the biosorption of Cd (II), Pb (II) and Cu (II) onto the dry

fungal biomass of Phanerochaete chryosporium in aqueous solution. At pH 6.0,

the maximum biosorption of Cd (II), Pb (II) and Cu (II) were found to be 13.24,

45.25 and 10.72 mg/g respectively. Within 2 h, more than 60 % of metal was

biosorbed and saturation was reached at about 6 h for all metals. Equilibrium data

fitted well to Langmuir model with correlation coefficient (R) 0.996 for Cd (II),

0.9959 for Pb (II) and 0.9927 for Cu (II). Maximum biosorption capacities for Cd

(II), Pb (II) and Cu (II) were found to be 27.79, 85.86 and 26.55 mg/g

respectively.

Seker et al [104] studied the biosorption of lead (II), cadmium (II) and nickel (II)

ions from aqueous solution onto Spirulina platensis. At optimum pH 6.0, removal

of lead (II), cadmium (II) and nickel (II) ions were found to be 92, 87 and 59 %

54

respectively. Equilibrium time for Pb (II), Cd (II) and Ni (II) was found to be less

than 1 h. Equilibrium data obtained was better represented by Freundlich,

Dubinin-Radushkevich and Temkin isotherm models. Biosorption kinetics

followed pseudo-second-order model. Activation energy for Pb (II), Cd (II) and

Ni (II) ions were found to be 44, –16 and 54 kJ/mol respectively. The

thermodynamic parameter indicated that the biosorption is endothermic,

irreversible and spontaneous in nature. Morphological characterization of S.

platensis was evaluated by Scanning Electron Microscope (SEM).

Sheng et al [105] investigated the biosorption of Pb (II), Cu (II), Cd (II), Zn (II)

and Ni (II) onto Sargassum sp., Padina sp., Ulva sp., and Gracillaria sp. - brown

seaweeds. The optimum pH for Pb (II) and Cu (II) was 5.0 and for Cd (II), Zn (II)

and Ni (II) were 5.5. Equilibrium time was attained at 60 min. Overall, Sargassum

sp. and Padina sp. showed higher potential for removal of metals. The maximum

uptake capacities for Pb (II), Cu (II), Cd (II), Zn (II) and Ni (II) were 1.16, .099,

0.76, 0.50 and 0.61 for Sargassum sp. and 1.25, 1.14, 0.75, 0.81 and 0.63mmol/g

for Padina sp. respectively. Functional groups were characterized by FTIR.

Shu-Juan et al [106] investigated the removal of cadmium from electroplating

wastewater by adsorption-precipitation method using waste Saccharomyces

cerevisiae (WSC). Better biosorption was observed at pH 4.0 to 6.0 and at pH 6.0,

biosorption was observed as 83.71 %. When biosorbent dosage increases from 15

to 16.25 g/L, percentage removal increases slowly and biosorbent dosage reaches

16.25 g/L, percentage removal reaches 86.44 %. As temperature increases from16

to 34oC, the biosorption rate increases and when the temperature increases from

22 to 28oC, biosorption rate gets upto 87 %. The maximum removal is over 88 %

55

at cadmium concentration of 26 mg/L, dosage of 16.25 g/L, temperature of 18oC,

pH 6.0 and precipitation time 4h. Functional groups and surface morphology were

characterized by FTIR and SEM respectively.

Singh et al [107] studied the removal of cadmium from wastewater using rice

polish an agricultural waste. The optimum pH was found to be 8.6 and maximum

removal at this pH was 92.15 %. Equilibrium was attained in 90 min. With the

increase of cadmium concentration from 100, 200 and 150 mg/L, percentage

removal of cadmium decreased from 96.95, 92.15 and 85.80 % respectively. With

the increase of temperature from 20 to 40oC, percentage removal of cadmium

decreased from 97.20 to 86.35. Biosorption isotherm fitted Langmiur isotherm

and maximum biosorption capacity was found to be 0.801 mg/g. Thermodynamic

parameters indicated that the system is spontaneous and exothermic in nature.

Taty-Costodes et al [108] studied the biosorption of Pb (II) and Cd (II) from

aqueous solution onto sawdust of Pinus sylvestris. The maximum uptake was

obtained at pH 5.5 for both metals. Rapid removal for both metals was found to be

less than 20 min, but contact time was maintained for 60 min to ensure that

equilibrium was really attained. With the increase of initial concentration from 1

to 10 mg/L, percentage removal of Pb (II) and Cd (II) increased from 84 to 98 %

and 80 to 95 % respectively. Biosorption isotherm was well fitted to Langmuir

isotherm and maximum biosorption capacity of Pb (II) and Cd (II) was found to

be 22.22 and 19.08 mg/g. Experimental data was better described by pseudo

second order model and intra particular diffusion is significant in order to

determine the sorption rate. Surface morphology was characterized by SEM.

56

Tuzen et al [109] studied the biosorption of Hg (II), Cd (II) and Pb (II) ions onto

Chlamydomonas reinhardtii. Equilibrium was attained within 60 min. Optimum

algal dosage was selected as 800 mg/L. The maximum biosorption for Hg (II), Cd

(II) and Pb (II) was observed at pH 6.0, 6.0 and 5.0 respectively. Biosorption

capacity of Hg (II), Cd (II) and Pb (II) did not significantly change with the

change in temperature. Biosorption isotherm followed Freundlich isotherm and

maximum biosorption capacity of Hg (II), Cd (II) and Pb (II) from Langmuir

isotherm models was found to be 0.61, 0.69 and 0.71mmol/g respectively.

Experimental data was better described by pseudo second order model. Functional

groups were characterized by FTIR.

Vimala and Das [110] studied the biosorption of Cd (II) and Pb (II) from aqueous

solutions by oyster mushroom (Pleurotus platypus), button mushroom (Agaricus

bisporus) and milky mushroom (Calocybe indica). Equilibrium time was found to

be 60, 240 and 240 min for P. platypus, A. bisporus and C. indica respectively.

Optimum pH was found to be 6.0 and 5.0 for Cd (II) and Pb (II) respectively for

all the mushrooms. Optimum cadmium dosage was found to be 3, 4 and 5 g/L for

P. platypus, A. bisporus and C. indica respectively. Initial concentration increased

the biosorption of cadmium and lead. Langmuir biosorption model was better

suitable than Freundlich model for all mushrooms. The maximum metal uptake

for Cd (II) was 34.96, 29.67 and 24.09 mg/g for P. platypus, A. bisporus and C.

indica respectively.

Wei-Chen et al [111] studied the biosorption of cadmium on poly vinyl alcohol

(PVA) immobilized recombinant Escherichia coli. Optimum pH was found to be

5.0, biosorption capacity of biomass-free PVA beads was 1.30 mg/g and

57

biosorption capacity of PVA-immobilized cells with biomass dosage of 8.42 and

19.5 wt % was found to be 2.18 and 4.41 mg/g respectively. With the increase of

temperature from 20 to 42oC, there is no significant change in metal uptake

capacity. At 10 mg/L, PVA-immobilized cells with biomass loading of 15.4 and

9.71 wt % had higher removal of cadmium of 83 and 58 % respectively and for

biomass-free PVA beads, there is no significant effects on the percentage removal

of cadmium. Biosorption kinetics followed pseudo-second-order model.

Equilibrium data fitted well to Langmuir model and maximum capacity onto

biomass-free PVA beads was 6.35 mg/g, PVA-immobilized cells with biomass

loading of 9.71 and 15.4 wt % was found to be 8.67 and 10.66 mg/g. with the

increase of biomass dosage from 8.4 to 332.0 wt %, the metal uptake capacity

increased from 2.31 to 4.29 mg/g.

Xiao et al [112] studied the Cd (II) bisorption by endophytic fungas (EF)

Microsphaeropsis sp. LSE 10 isolated from cadmium hyperaccumulator Solanum

nigrum L. Equilibrium was attained in 3 h. At pH 6.5, highest biosorption capacity

was occurred. With the increase of Cd (II) concentration from 20, 50 and 100

mg/L, the biosorption capacity increased from 15.5, 35.3 and 69.7 mg/g

respectively. At biomass dosage of 1 g/L, maximum biosorption capacity was

occurred. Biosorption isotherm followed Langmiur isotherm and maximum

biosorption capacity of Cd (II) was found to be 247.5 mg/g. Experimental data

was better described by pseudo second order model. Functional groups were

characterized by FTIR.

Xue-Jaing et al [113] studied the removal of Cd (II) and Pb (II) from aqueous

solution onto dried activated sludge. Equilibrium time was attained at 60 min for

58

Cd (II) and Pb (II). At pH 6.0 and 4.0, the maximum biosorption for Cd (II) and

Pb (II) were found to be 26.5 and 39.3 mg/g respectively. As the initial cadmium

concentration varied from 20 to 100 mg/L, the equilibrium capacity increased

from 9.8 to 61.3 mg/g. Kinetics followed pseudo-second-order model for both

metals. Equilibrium data obtained was better represented by Langmuir isotherm

model than Freundlich isotherm model for both metals. Maximum biosorption

capacities for Cd (II) and Pb (II) were found to be 84.3 and 131.6 mg/g

respectively. Activation energy for Cd (II) and Pb (II) obtained were 21.4 and

17.21 kJ/mol respectively. Functional groups were analyzed by FTIR.

Yalcinkaya et al [114] studied the cadmium biosorption onto calcium alginate,

entrapped live and dead fungal biomass Trametes versicolor mycelia. Maximum

biosorption of cadmium occurred pH between 5.0and 6.0. Equilibrium time was

found to be 60 min. Initial cadmium concentration was raised upto 600 mg/L, the

cadmium uptake was on calcium alginate, entrapped live and dead T. versicolor

was found to be 39.1, 102.3 and 120mg/g respectively. Both Freundlich and

Langmuir isotherms models were fitted well to the equilibrium data, with

maximum capacity of 40.1, 141.3 and 164.3 mg/g for calcium alginate, entrapped

live and dead T. versicolor. Biosorption kinetics followed pseudo-second-order

model. Surface morphology of calcium alginate, fungas entrapped alginate beads

were characterized SEM.

Yun-Guo et al [115] studied the potential of living Aspergillus niger for the

removal of cadmium and zinc from aqueous solution. At pH 4.0 and 6.0,

maximum Cd (II) and Zn (II) uptake capacities were found to be 15.1 and 18.25

mg/g respectively. Equilibrium time was attained within 24 h for both Cd (II) and

59

Zn (II). The best temperature and agitation speed were found to be in range of 25

to 30oC and 120 rpm for metal ions. At initial Cd (II) concentration of 75 mg/L

and Zn (II) concentration of 150 mg/L, the maximum uptake capacities were

found to be 15.50 and 23.70 mg/g respectively. Equilibrium data was better fitted

to Langmuir model and maximum uptake for Cd (II) and Zn (II) were found to be

18.08 and 26.10 mg/g respectively. Biosorption followed pseudo second order

kinetics.

Yuh-Shan and Ofomaja [116] studied the biosorption of cadmium ions from

aqueous solution onto coconut copra meal, a waste product of coconut oil

production. At pH 6.0, maximum removal of cadmium was occurred. With the

increase of copra meal dosage from 5.0 to 30 g/dm3, the biosorption capacity

decreased from 8.20 to 2.29 mg/g. Equilibrium data obtained was best fitted to

two –parameter Langmuir and three-parameter Redlich-Peterson isotherms. With

the increase of temperature from 299 to 333 K, saturated monolayer biosorption

capacity decreased from 4.99 to 1.97 mg/g. Thermodynamic parameters indicated

that biosorption process is exothermic and spontaneous in nature.

Zhou et al [117] studied the biosorption of Cd (II) and Cu (II) on a novel

exopolysaccharide (EPS) secreted by a mesophilic bacterium namely Wangia

profunda (SM-A87) isolated from deep-sea sediment. With the increase of EPS

dosage from 0.05 to 0.4 g/L, the biosorption amounts for Cu (II) and Cd (II)

increased from 17.50 to 66.0 mg/g and 17.90 to 39.75 mg/g respectively. At pH

5.0 and 6.0, the maximum uptakes for Cu (II) and Cd (II) were found to be 48.0

and 39.75 mg/g respectively. Equilibrium data obtained was better represented by

Langmuir isotherm model than Freundlich isotherm model for both metals. The

60

maximum biosorption capacity for Cu (II) and Cd (II) was found to be 128.21 and

116.28 mg/g respectively. Biosorption kinetics followed pseudo-second-order

model compared to pseudo-first-order and intraparticle diffusion models.

Functional groups were analyzed by FTIR.

Ziagova et al [118] studied the biosorption of cadmium and chromium ions onto

Staphylococcus xylosus and Pseudomonas species in single and binary mixtures.

Optimum Cd (II) pH values were found to be 7.0 for Pseudomonas sp., and 6.0 for

S. xylosus, with 60 % of Cd (II) removal for both bacteria’s. Equilibrium time for

Cd (II) was attained at 30 and 60 min for Pseudomonas sp., and S. xylosus

respectively. With the increase of initial Cd (II) concentration from 10 to 150

mg/L, the loading capacity for both bacteria’s increased from 5 to 500 mg/g.

Equilibrium data obtained was better represented by Freundlich isotherm model.

Maximum Cd (II) uptake was found to be 278 and 250 mg/g for Pseudomonas sp.,

and S. xylosus respectively.

61

Response Surface Methodology

Amini et al [119] studied to model and optimize Ni (II) biosorption from aqueous

solution onto NaOH pretreated Aspergillus niger. Equlibrium was reached at 240

min. The optimum values of pH, intial nickel concentration and biomass dosage

were found to be 6.25, 30.0 mg/L and 2.98 g/L respectively. At optimum

conditions, the optimum uptake of nickel was found to be 4.82 mg/g (70.30 %).

Biosorption followed pseudo-second order and intra-particular diffusion rate

equation. Equilibrium data was fitted to Langmuir model and the maximum

capacity was found to be 6.80 mg/g. Functional groups was characterized by FTIR

analysis.

Amini et al [120] investigated the biosorption of cadmium ions on NaOH

pretreated Aspergillus niger. Biosorption process was determined and the process

was then optimized by response surface methodology (RSM). The optimum

values of pH, intial cadmium concentration and biomass dosage were found to be

5.95, 30.0 mg/L and 1.6 g/L respectively, at contact time of 1440 min. At

optimum conditions, the uptake of cadmium was found to be 10.14 mg/g (82.2

%).

Azila et al [121] studied lead ions biosorption onto immobilized cells of

Pycnoporus sanguineus. Initial Pb (II) concentration, pH and P.sanguineus dosage

are the independent variables. The combined effect of these variables were

analysed by central composite design using response surface methodology. The

optimum values of pH, biomass dosage, and lead ion concentration was found to

be 4, 10.0 g/L and 200 mg/L respectively. At optimum conditions, the removal

62

efficiency was found to be 97.7 %. The experimental observations are in good

agreement with the predicted observations.

Can et al [122] studied the biosorption of nickel ions from aqueous solution onto

Pinus sylvestris ovulate cones. A 24 full factorial central composite design was

employed for experimental design. At pH 6.0 and biomass dosage of 24 g/L,

maximum removal efficiency was found to be about 100 %. The optimum values

of pH, intial nickel concentration and biomass dosage were found to be 6.17,

11.175 mg/L and 18.8 g/L respectively. At optimum conditions, the removal

efficiency was found to be 99.91 %. Surface morphology was characterized by

SEM analysis.

Cojocaru et al [123] investigated the optimization of copper ions biosorption onto

dried yeast Saccharomyces biomass. Experimental data was best fitted to Sips

model. According to Langmuir isotherm, the maximum capacity was forund to be

2.59 mg/g. thermodynamic parameters indicated that the system is endothermic

and spontaneous in nature. The optimum values of pH, intial copper concentration

and biomass dosage were found to be 3, 25.7 mg/L and 2.32 % (w/v) respectively.

At optimum conditions, the removal efficiency of copper was found to be 43.08

%.

Fereidouni et al [124] investigated the optimization of Cd (II) and Ni (II)

biosorption from aqueous solution onto Saccharomyces cerevisia and Ralstonia

eutropha nonliving biomass. The optimum percentage removal of Cd (II) and Ni

(II) onto S. cerevisia was found to be 43.4 and 65.5 % respectively, at pH of 7.1,

biomass dosage of 4.07 g/L, initial Cd (II) concentration of 37 mg/L and initial Ni

(II) concentration of 16 mg/L. The optimum percentage removal of Cd (II) and Ni

63

(II) onto R. eutropha was found to be 52.7 and 50.1 % respectively, at pH of 5.0,

biomass dosage of 2.32 g/L, initial Cd (II) concentration of 37 mg/L and initial Ni

(II) concentration of 28 mg/L. The experimental observations are in good

agreement with the predicted observations. Functional groups and surface

morphology were characterized by FTIR and SEM analysis respectively.

Ghorbania et al [125] studied biosorption of cadmium on Saccharomyces

cerevisiae using central composite design (CCD) under respeonce surface

methodology (RSM). The analysis of variance (ANOVA) demonstrates that the

model was significant. The optimum values were found to be pH 5.0, S.cerevisiae

dosage of 3.8 g/L, and cadium concentration of 19 mg/L. At initial cadmium

concentration of 26.46 mg/L and S.cerevisiae dosage of 2.13 g/L, optimum

cadmium uptake of 6.71 mg/g was obtained. Equilibrium data was better fitted to

Langmuir model. Biosorption followed both monolayer and intra-particle

diffusion mechanisms. Surface morphology was analysed by SEM.

Hasan et al [126] investigated the optimization of Pb (II) biosorption onto

Aeromonas hydrophilia. A 24 full factorial central composite design was

employed for experimental design. The experimental observations are in good

agreement with the predicted observations. The optimum values of pH, intial lead

concentration, biomass dosage and temperature were found to be 5, 259 mg/L, 1.0

g and 20oC respectively. At optimum conditions, the maximum uptake of lead was

found to be 122.18 mg/g. Equilibrium data was found to follow both Langmuir

and D-R model. According to Langmuir isotherm, the maximum capacity was

found to be 122.18 mg/g. Functional groups was characterized by FTIR analysis

64

Ozer et al [127] investigated the copper biosorption onto Enteromorpha prolifera,

a green algae and optimized using RSM. Equilibrium was attained after 60 min.

The optimum parameters were found to be at pH 4.0, initial concentration of 200

mg/L, biosorbent dosage of 1.2 g/L and temperature of 25oC. Biosorption

followed pseudo-second order kinetics. Equilibrium data was better fitted

toFreundlich model than the Langmuir model. Thermodynamic paremters

indicated that the system is spontaneous and exothermic in nature. The maximum

capacity was found to be 57.14 mg/g at 25oC and pH 4.0.

Preetha and Viruthagiri [128] studied copper biosprtion onto Rhizopus arrhizus

using a 24 full factorial central composite design using response surface

methodology. The analysis of variance (ANOVA) demonstrates that the model

was significant. The optimum values were found to be initial copper concentration

of 53.84 mg/L, pH 4.14, R. arrhizus dosage of 8.17 g/L and temperature of

37.75oC. At these optimum parameters, maximum removal of copper was found to

be 98.34 %. The experimental values were very close to RSM values, indicates

that the design of experiments could be effectively used to optimize the process

parameters.

Sahu et al [129] studied the biosorption capacity of chromium (VI) on activated

Tamarind wood. For optimization of chromium, a 24 full factorial central

composite design was employed. The optimum values of pH, Cr (VI)

concentration, biomass dosage and temperature was found to be 5.41, 20.15mg/L,

4.3 g/L and 32oC. At optimum conditions, the removal efficiency was found to be

89.94 %. The experimental observations are in good agreement with the predicted

observations. Functional groups and surface morphology were characterized by

FTIR and SEM analysis respectively,

65

Continuous Process

Apiratikul and Pavasant [130] investigated the biosorption of Pb (II), Cu (II) and

Cd (II) onto dried green macroalga Caulerpa lentillifera in batch and continous

systems. Equilibrium was attained within 10-20 min. The optimum dosage for Pb

(II), Cu (II) and Cd (II) were found to be 14, 17.5 and 10 g/L respectively.

Equilibrium data were fitted by both Langmuir and Sips isotherms models.

Biosorption kinetics followed pseudo-second-order model. Maximum biosorption

capacities were found to be in order Pb (II) (0.136 mol/kg) > Cu (II) (0.125

mol/kg) > Cd (II) (0.042 mol/kg). The average sorption capacity calculated from

breakthrough curve for Pb (II), Cu (II) and Cd (II) were found to be 0.136, 0.085

and 0.083mol/kg respectively. The average sorption capacity calculated from

Thomas model for Pb (II), Cu (II) and Cd (II) were found to be 0.129, 0.087 and

0.084mol/kg respectively.

Aksu and Gonen [131] studied the removal of phenol from aqueous solution by

Mowital®B30H resin, immobilized dried activated sludge. At pH 1.0, the

equilibrium phenol uptake was found to be 55.6 mg/g. With the increase in flow

rate and inlet phenol concentration, the equilibrium phenol uptake decreased and

increased respectively. At an inlet phenol concentration of 502.3 mg/L, the

maximum capacity was found to be 9.0 mg/g. Equilibrium data was very well

fitted to Langmuir model. Adams-Bohart, Thomas, Clark and Yoon-Nelson

models were found suitable for explaining the dynamic behavior of the column.

Cabuk et al [132] studied the removal of lead (II) onto Bacillus sp. ATS-2 isolated

from polluted soil immobilized with a silica matrix in batch and fixed bed column.

Equilibrium was attained within 60 min. At pH of 4.0, maximum yield of 91.73 %

66

was found. At flow rates of 60 and 180ml/h, the bioosporption yields were found

to be 91.23 and 89.46 % respectively. The optimum bed height was found to be 10

cm. The maximum yield of 91.72 and 91.73 % was attained at concentration of 25

and 50 mg/L respectively. Equilibrium data was well fitted to Langmuir,

Freundlich and D-R isotherm models. The functional groups were characterized

by FTIR analysis.

Calero et al [133] studied the biosorption of chromium (III) from aqueous solution

onto olive stone in a continuous mode. The breakthrough and saturation time

increased, with the increase of bed depth and same is resulted when the flow rate

is decreased. With the increase of Cr (III) concentration, the biosorption capacity

also increases and reaches a value close to 0.800 mg/g. The Adams-Bohart and

Dose-Responce models were found to be very satisfactory for the prediction of

breakthrough curve. The high value of pH at the beginning is due to H+ ions

sorbed in the matrix of biomass and the pH tends to a constant value, when the

sites in the bed are saturated.

Chen [134] studied biosorption of strontium onto root tissues of Amaranthus

spinosus in aquoues solution. The equilibrium was in the range of 6 h.

Equilibrium data were fitted by both Langmuir and Freundlich isotherms.

Maximum biosorption capacity was found to be 12.89 mg/g. With the increase of

temperature from 10 to 40 oC, the biosorption capacity decreased from 18.13 to

9.47 mg/g respectively. With the increase of flow rates from 0.25, 0.5 and 0.75

mL/min, the overall biosorption capcities were found to be 19.3, 18.8 and 17.9

mg/g respectively.

67

Chu and Hashim [135] investigated biosorption of copper by Sargassum

baccularia, a brown algae immobilized onto polyvinyl alcohol (PVA) gel beads

with fixed bed experiments. Breakthrough profiles were described by Bohart-

Adams model. With the increase of flow rate from 1 to 1.5 mL/min, the time

required for complete saturation decreased from 900 to about 600 min. At higher

flow rates, the breakthrough curve obtained shows a much shorter clear period

before the breakthrough point was obtained. A similar trend was observed, with

the increase of fedd concentration. The calculated breakthrough curves were in

good agreement with the experimental ones.

Gokhale et al [136] studied the chromium (VI) biosorption by immobilized

Spirulina platensis in calcium alginate beads in packed column. Bead size of 2.6

mm, biomass loading of 2.6 % (w/v) and calcium alginate concentration of 2 %

(w/v) are the optimum bead parameters for conducting the experiments.

Equilibrium data was well fitted to Freundlich isotherm model. Biosorption

kinetics followed pseudo first order model. With the increase of bed height, the

breakthrough time and exhaustion time increased. As the flow rate increased, the

breakthrough curve became steeper. The Thomas and Yoon-Nelson model were in

good agreement with the experimental data.

Hasan and Srivastava [137] studied the biosorption of copper ions on free and

polysulphone immobilized biomass of Arthrobacter sp. from aqueous solution in

batch and continuous systems. Equilibrium data was better fitted to Langmuir

model and maximum uptake capacity of Cu (II) was found to be 175.87 and 158.7

mg/g for free and immobilized biomass respectively. Biosorption followed

pseudo-second order kinetics. At bed height of 20 cm and feed rate of 3.5

68

mL/min, the maximum removal (89.56 %) and uptake (32.64 mg/g) were

obtained. The BDST model was in good agreement with the experimental data.

Hawari and Mulligan [138] investigated the biosorption of Pb (II), Cu (II), Cd (II)

and Ni (II) onto calcium treated anaerobic granules from aqueous solution using

continuous column operation. The average biosorption coloumn capacity were

found to be 1.55, 0.88, 0.89 and 0.51 meq/g for Pb (II), Cu (II), Cd (II) and Ni (II)

respectively. The pH of feed solution was 4.0 for all metals, while the pH of the

exit solution was slightly increased (5.0 to 5.5) for most of the experiments before

the breakthrough point. At the breakthrough point, the pH was adjusted to the

value of the feed solution.

The biosorption of Cr (VI) onto waste acorn of Quercus ithaburensis was

performed by Malkoc et al [139] in a fixed-bed. Highest bed capacity (26.65

mg/g) was obtained at pH 2.0. At lower flow rates (5 mL/min), maximum bed

capacity and highest breakthrough was found to be 30.23 mg/g and 1440 min

respectively. Same trend was observed for particle size. Yoon-Nelson model

correlated better than Thomas model at tested flow rate and particle size. For

determinations of functional groups and surface of the particle, biosorbent is

characterized by FTIR ansd SEM.

Malkoc and Nuhoglu [140] studied Cr (VI) biosorpion from aqueous solution onto

tea waste factory in fixed bed. The longest breakthrough time (480 min) and

maximum biosorption (33.71 mg/g) was obtained at pH 2. Maximum bed

capacities were found to be 55.65, 40.41 and 33.71 mg/g at flow rates of 5, 10 and

20 mL/min respectively. Maximum bed capacities were found to be 27.67, 34.46,

40.41 and 43.67 mg/g at Cr (VI) concentration of 50, 75, 100 and 200 mg/L

69

respectively. Thomas model gave good agreement between experimental and

calculated breakthrough curves.

Mata et al [141] studied the biosorption of copper onto sugar beet pectin gels

obtained from residues of sugar industries in fixed bed column. The optimum

conditions were 3 g of biomass, 25 mg/L metal ion concentration, 2 mL/min feed

flow rate and a reverse feeding system. With the increase in bed height, the

pressure drop in the column and saturation time increased. As the inlet metal

concentration and feed flow rate increased, the saturation time decreased. Both the

linear and nonlinear expressions of the Thomas model fitted the column

breakthrough curves.

Mungasavalli et al [142] investigated the biosorptgion of chromium onto dead

Aspergillus niger pretreated with Cetyl trimethyl ammomium bromide (CTAB) in

batch and column mode. Equilibrium was attained at 2 h. Equilibrium data were

fitted by both Langmuir and Freundlich isotherms. Biosorption kinetics followed

pseudo-second-order model. Maximum biosorption capacities were found to be

14.5, 15.2, 10.6 and 11.6 mg/g at 5, 15, 22 and 30oC respectively. Functional

groups were analyzed by FTIR. The optimum pH of 3.0 was set for the continuous

mode. Yan model was better fitted than the Thomas model. The biosorption

capacity was found to be 5 mg/g, which was less than the batch mode. Functional

groups were characterized by FTIR analysis.

Pamukoglu and Kargi [143] investigated the copper ions biosorption onto

pretreated powdered waste sludge (PWS) in a completely mixed reactor. With the

increase in dosage of PWS, the percentage removal of copper also increased. But

the removal of copper decreased, with the increase in feed flow rate and feed

70

copper concentration. Inoder determine the biosorption capacity and rate constant,

a modified Bohart-Adams equation was used. The biosorption capacity and rate

constant were found to be 27.7 g Cu.kg-1 PWS and 15.1m3 kg-1 h-1 respectively.

Perez et al [144] studied the biosorption of Cr (III) by Citrus cinensis waste from

aqueous solution in batch and continous system. Equilibrium was attained in 3

days. Biosorption kinetics followed pseudo second order model. Equilibrium data

was well fitted to Sips and Redlich-Peterson isotherm models. With the increase

of pH from 3 to 5, the maximum sorption capacity increased from 0.57 to 1.44

mmol/g, according to the Sips model. BDST model successfully describes the

breakthrough curves. The sorption capacity in continuous system was less than

that of batch system, this is due to the slow kinetics.

Preetha and Viruthagiri [145] studied the chromium biosorption using suspended

and immobilized cells of Rhizopus arrhizus in batch and packed bed reactor.

Biosorption kinetics followed pseudo second order model. Equilibrium data was

well fitted to Freundlich and Redlich-Peterson isotherm models. At 20 min of

residence time, maximum capacity was found to be 52.11 mg/g. As the bed height

increases, breakthrough point time and metal uptake are found to be increased.

The Thomas model does not represent the experimental data, as the rate of

sorption is slow during the initial period. The Adams-Bohart model was fitted

better at initial part of the breakthrough.

Sushera et al [146] investigated the removal of cadmium by dry Hydrilla

verticillata biomass by batch and continuous system. The equilibrium was attained

in 30 min. The optimum pH was found to be 5 and at 1 mg/L, the biosorption

efficiency was found to be high. The maximum biosorption capacity was found to

71

be 15 mg/g. The breakthrough curve from continous studies could purify 10 mg/L

and even below the detection limit of 0.02 mg/L. The cadmium influent-effluent at

0.5 and 1 g were reached at volumes of 4200 and 7800 mL respectively. With the

increase in influent flow rate, there is almost no effect on cadmium removal.

Vieria et al [147] studied the removal of chromium onto Sargassum sp. from

aqueous solution using packed bed column. The effluent Cr (VI) concentration

increased with time, indicating a decrease in the removal capacity. The

equilibrium time decreased from 60 to 45 min, with the increase of flow rate from

0.015 to 0.030 mL/s. With the increase in flow rate, the column capacity increased

for same chromium concentration and biosorbent dosage. Equilibrium data was

well fitted to both Langmuir and Freundlich isotherm model and maximum uptake

capacity was found to be 39.61 mg/g. Statistical design was applied and at the

optimum conditions the chromium capacity was found to be 19.06 mg/g.

Vijayaraghavan and Prabu [148] studied the copper (II) biosprption onto

Sargassum wightii, brown algae in batch and continuous mode. The maximum

capacity from Langmuir isotherm model was found to 115 mg/g at pH 4.5. At

optimum conditions of 25 cm, 5 mL/min and 100 mg/L, the copper uptake was

found to be 52.6 mg/g. The Thomas and Yoon-Nelson models were found to be

very satisfactory for the prediction of breakthrough curve. The BDST model

predicted values coincide with experimental values with high correlation

coefficients.

Ping Chen Vilar et al [149] investigated removal of Cu (II) onto marine algae Gelidium and

algae composite material from aqueous solution in a packed bed column. With the

increase of the inlet copper concentration, the copper uptakes are similar, 128 amd

72

127 mg/g for algae Gelidium and, 31 and 25 mg/g for composite material. With

the increase of the ionic strength, the sorption capacity and breakthrough time

decreases. The influence of temperature on metal uptake was negligible. For the

same flow rate, as the inlet concentration increases, the breakthrough time

decreases. With copper concentration of 50 and 25 mg/L, and at pH 5.3, the

maximum uptake capacity of algae Gelidium and composite material was found to

be 13 and 3 mg/g respectively.

Vilar et al [150] investigated the biosorption of cadmium in batch and continuous

systems onto marine algae Gelidium, algal waste from agar extraction and

composite material. The uptake capacity decreased with pH. Equilibrium data

were well described by both Langmuir and Langmuir-Freundlich isotherms. The

uptake capacities of Gelidium, algal waste and composite material were found to

be 20.5, 15 and 8.6 mg/g respectively. LDF and Homogeneous diffusion mass

transfer models were able to fit the kinetic experimental data.The breakthrough

time for algae and comnposite material were found to be 685 and 172 min

respectively, which results from the higher capacity for algae (19.8 mg/g)

compared with the composite material (4.9 mg/g).

Yan and Viraraghavan [151] studied the removal of Pb, Cd, Ni and Zn from both

single and multi component metal solution onto Mucor rouxii biomass

immobilized in a polysulfone matrix in a column. Thomas model was found

suitable to describe the column kinetics. For single component metal solutions, the

removal capcities were found to be 4.06, 3.76, 0.36 amd 1.36 mg/g for Pb, Cd, Ni

and Zn respectively. For multi component metal solution containing Cd, Ni and

Zn, the metal capacities wrer found to be 0.36, 0.31 and 0.40 mg/g for Cd, Ni and

Zn respectively.

73

References

[1]. Acar, F.N. and Malkoc, E., The removal of chromium (VI) from aqueous solution by Fagus orientalis L., Bioresource Technology, 94(1), (2004), 13-15

[2]. Agarwal, G.S., Bhuptawat, H.K. and Chaudhari, S., Biosorption of aqueous chromium (VI) by Tamarindus indica seeds, Bioresource Technology, 97(7), (2006), 949-956

[3]. Aksu, Z. and Balibek, E., Chromium (VI) biosorption by dried Rhizopus arrhinus: Effect of salt (NaCl) concentration on equilibrium and kinetic parameters, Journal of Hazardous Materials, 145(1-2), (2007), 210-220

[4]. Arslan, G. and Pehlivan, E., Batch removal of chromium (VI) from aqueous solution by Turkish brown coals, Bioresource Technology, 98(15), (2007), 2836-2845

[5]. Ashok, V. B., Ameeta, R. K. and Smita, S. Z., Removal of chromium (VI) ions from aqueous solution by adsorption onto two marine isolates of Yarrowia lipolytica, Journal of Hazardous Materials, 170, (2009), 487–494

[6]. Baran, A., Bicak, E., Baysal, S.H. and Onal, S., Comparative studies on the adsorption of Cr (VI) ions onto various sorbents, Bioresource Technology, 98(3), (2007), 661-665

[7]. Baral, S.S., Das, S.N. and Rath, P., Chaudhury, G.R., Chromium (VI) removal by calcined bauxite, Bioresource Technology, 34(1), (2007), 69-75

[8]. Baral, S.S., Das, S.N. and Rath, P., Hexavalent chromium removal from aqueous solution by adsorption on treated sawdust, Biochemical Engineering Journal, 31(3), (2006), 216-222

[9]. Barrera, H., Urena-Nunez, F., Bilyeu, B. and Barrera-Diaz, C., Removal of chromium and toxic ions present in drainage by ectodermis of opuntia, Journal of Hazardous Materials, 136(3), (2006), 846-853

[10]. Bayat, B., Comparative study of adsorption properties of Turkish fly ashes II, The case of chromium (VI) and cadmium (II), Journal of Hazardous Materials, 95(3), (2002), 275-290

[11]. Bhattacharya, A.K., Naiya, T.K., Mandal, S.N. and Das, S.K., Adsorption, kinetics and equilibrium studies on removal of Cr (VI) from aqueous solutions using different low-cost adsorbents, Chemical Engineering Journal, 137, (2008), 529–541

74

[12]. Blazquez, G., Hernainz, F., Calero, M., Martín-Lara, M.A. and Tenorio, G., The effect of pH on the biosorption of Cr (III) and Cr (VI) with Olive stone, Chemical Engineering Journal, 148, (2009), 473–479

[13]. Bishnoi, N.R., Bajaj, M., Nivedita, S. and Asha, G., Adsorption of Cr (VI) on activated rice husk carbon and activated alumina, Bioresource Technology, 91(3), (2004), 305-307

[14]. Chergui, A., Bakhti, M.Z., Chahboub, A., Haddoum, S., Selatnia, A. and Junter, G.A., Simultaneous biosorption of Cu2+, Zn2+ and Cr6+ from aqueous solution by Streptomyces rimosus biomass, Desalination, 206, (2007), 179–184

[15]. Donmez, G.C., Aksu, Z., Ozturk, A. and Kutsal, T., A comparative study on heavy metal biosorption characteristics of some algae, Process Biochemistry, 34, (1999), 885–892

[16]. Donmez, G. and Aksu, Z., Removal of chromium (VI) from saline wastewaters by Dunaliella species, Process Biochemistry, 38(5), (2002), 751-762

[17]. El-Sikaily, A., El Nemr, A., Khaled, A. and Abdelwehab, O., Removal of toxic chromium from waste water using green algae Ulva lactuca and its activated carbon, Journal of Hazardous Materials, 148, (2007), 216-228

[18]. Erdem, M., Altundogan, H.S. and Taumen, F., Removal of hexavalent chromium by using heat-activated bauxite, Minerals Engineering, 17(9-10), (2004), 1045-1052

[19]. Erol, P. and Turkan, A., Biosorption of chromium (VI) ion from aqueous solutions using Walnut, Hazelnut and Almond shell, Journal of Hazardous Materials, 155, (2008), 378–384

[20]. Ertugay, N. and Bayhan, Y.K., Biosorption of Cr (VI) from aqueous solutions by biomass of Agaricus bisporus, Journal of Hazardous Materials, 154, (2008), 432–439

[21]. Gary, V.K., Gupta K., Kumar, R. and Gupta, R.K.,

Adsorption of Chromium form aqueous solution on treated sawdust, Bioresource Technology, 92(1), (2004), 79-81

[22]. Gokhale, S.V., Jyoti, K.K. and Lele, S.S., Kinetic and equilibrium modeling of chromium (VI) biosorption on fresh and spent Spirulina platensis/Chlorella vulgaris biomass, Bioresource Technology, 99, (2008), 3600-3608

75

[23]. Gupta, V.K., Shrivastava, K. and Jain, N., Biosorption of Cr (VI) from aqueous solutions by green algae Spirogyra species, Water Resource, 35(17), (2001), 4079-4085

[24]. Gupta, V.K. and Ali, I., Removal of lead and chromium from wastewater using bagasse fly ash-a sugar industry waste, Journal of Colloid and Interface Science, 271(2), (2004), 321-328

[25]. Gupta, S. and Babu, B.V., Adsorption of Cr (VI) by a low-cost adsorbent prepared from neem leaves, Proceeding of National Conference on Environmental Conservation (NCEC-2006), BITS Pilani, September 1-3, (2006), 175-180

[26]. Gupta, V.K. and Rastogi, A., Biosorption of hexavalent chromium by raw and acid-treated green alga Oedogonium hatei from aqueous solutions, Journal of Hazardous Materials, 163, (2009), 396-402

[27]. Gupta, V.K. and Rastogi, A., Sorption and desorption studies of chromium (VI) from nonviable cyanobacterium Nostoc muscorum biomass, Journal of Hazardous Materials, 154, (2008), 347-354

[28]. Han, X., Wong, Y.S., Wong, M.H. and Tam, N.F.Y., Biosorption and bioreduction of Cr (VI) by a micro algal isolate chlorella miniate, Journal of Hazardous Materials, 146(1-2), (2007), 65-72

[29]. IIhan, S., Nourbakhsh, N.M., Kilicarslan, S. and Ozdag, H., Removal of copper, lead, and chromium ions from industrial waste waters by staphylococcus saprophyticus, Turkish Electronic Journal of Biotechnology, 2, (2004), 50-57

[30]. Karthikeyan, T., Rajgopal, S. and Minranda, L.R.,

Chromium (VI) adsorption from aqueous solution by hevae brasilinesis sawdust activated carbon, Journal of Hazardous Materials, 124(1-3), (2005), 192-199

[31]. Khambhaty, Y., Mody, K., Basha, S. and Jha, B., Kinetics, equilibrium and thermodynamic studies on biosorption of hexavalent chromium by dead fungal biomass of marine Aspergillus niger, Chemical Engineering Journal, 145, (2009), 489-495

[32]. Kiran, B., Kaushik, A. and Kaushik, C.P., Biosorption of Cr (VI) by native isolate of lyngbya putealis (HH-15) in the presence of salts, Journal of Hazardous Materials, 141(3), (2007), 662-667

76

[33]. Kumar, R., Bishnoi, N.R., Garima and Bishnoi, K., Biosorption of chromium (VI) from aqueous solution and electroplating wastewater using fungal biomass, Chemical Engineering Journal, 135, (2008), 202–208

[34]. Lakshmanraj, L., Gurusamy, A., Gobinath, M.B. and Chandra Mohan, R., Studies on the biosorption of hexavalent chromium from aqueous solutions by using boiled mucilaginous seeds of Ocimum americanum, Journal of Hazardous Materials, 169, (2009), 1141-1145

[35]. Loukidou, M.X., Zouboulis, A.I., Karapantsis, T.D. and Matis, K.A., Equilibrium and Kinetic modeling of Cr (VI) biosorption by aeromonas caviae, Colloids and Surfaces A: Phyiscochemical and Engineering Aspects, 242(1-3), (2004), 93-104

[36]. Malkoc, E., Nuhoglu, Y. and Dundar, M., Adsorption of chromium (VI) on pomace-an olive oil industry waste: Batch and Column studies, Journal of Hazardous Materials, 138(1-2), (2006), 142-151

[37]. Maria, X. L., Anastasios, I. Z., Thodoris, D. K. and Kostas A. M., Equilibrium and kinetic modeling of Cr (VI) biosorption by Aeromonas caviae, Colloids and Surfaces A: Phyiscochemical and Engineering Aspects, 242, (2004), 93-104

[38]. Melo, J.S. and DSouza, S.F., Removal of chromium by mucilaginous seeds of Ocimum basilicum, Bioresource Technology, 92(2), (2004), 151-155

[39]. Mor, S., Ravindra, K. and Bishnol, N.R., Adsorption of chromium from aqueous solution by activated alumina and activated charcoal, Bioresource Technology, 98(4), (2007), 954-957

[40]. Moussavi, G. and Barikbin, B.,

Biosorption of chromium (VI) from industrial wastewater onto pistachio hull waste biomass, Chemical Engineering Journal, 162, (2010), 893-900

[41]. Murphy, V., Hughes, H. and McLoughlin, P., Comparative study of chromium biosorption by red, green and brown seaweed biomass, Chemosphere, 70, (2008), 1128-1134

[42]. Oliveira, E.A., Montanher, S.F., Andrade, A.D., Nobrega, J.A. and

Rollemberg, M.C., Equilibrium studies for the sorption of chromium and nickel from aqueous solutions using raw rice bran, Process Biochemistry, 40(11), (2005), 3485-3490

77

[43]. Ozdemir, G., Ceyhan, N., Ozturk, T., Akirmak, F. and Cosar,T.,

Biosorption of chromium (VI), cadmium (II) and copper (II) by pantoea sp. TEM 18, Chemical Engineering Journal, 102(3), (2004), 249-253

[44]. Ozdemir, G., Ceyhan, N., Ozturk, T., Isler, R. and Cosar,T., Heavy metal biosorption by biomass of Ochrobactrum anthropi producing exopolysaccharide in activated sludge, Bioresource Technology, 90(1), (2003), 71-74

[45]. Quintelas, C., Fernandes, B., Castro, J., Figueiredo, H. and Tavares, T., Biosorption of Cr (VI) by three different bacterial species supported on granular activated carbon-A comparative study, Journal of Hazardous Materials, 153, (2008), 799–809

[46]. Radojka, R. and Marina, S., Biosorption of Cr (VI) and Cu (II) by waste tea fungal biomass, Ecological Engineering, 34, (2008), 179–186

[47]. Rifaqat, A.K.R. and Rehman, F., Adsorption studies on fruits of Gular (Ficus glomerata): Removal of Cr (VI) from synthetic wastewater, Journal of Hazardous Materials, 181, (2010), 405–412

[48]. Romero-Gonzalez, J., Peralta-Videa, J.R., Rodriguez, E., Ramirez, S.L.

and Gardea-Torresdey, J.L., Determination of thermodynamic parameters of Cr (VI) adsorption from aqueous solution onto agave lechuguilla biomass, Journal of Chemical Thermodynamics, 37(4), (2005), 343-347

[49]. Sahin, Y. and Ozturk, A., Biosorption of chromium (VI) ions from aqueous solution by the bacterium bacillus thuringiensis, Process Biochemistry, 40(5), (2005), 1895-1901

[50]. Sari, A. and Tuzen, M., Biosorption of total chromium from aqueous solution by red algae (Ceramium virgatum): Equilibrium, kinetic and thermodynamic studies, Journal of Hazardous Materials, 160, (2008), 349-355

[51]. Sarin, V. and Pant, K.K., Removal of chromium from industrial waste by Eucalyptus bark, Bioresource Technology, 97(1), (2006), 15-20

[52]. Selvaraj, K., Manonmani, S. and Pattabhi, S., Removal of hexavalent chromium using distillery sludge, Bioresource Technology, 89(2), (2003), 207-211

78

[53]. Shaik, B., Murthy, Z.V.P. and Jhaa, B., Biosorption of hexavalent chromium by chemically modified seaweed Cystoseira indica, Chemical Engineering Journal, 137, (2008), 480-488

[54]. Sharma, Y.C., Singh, B., Agarwal, A. and Weng, C.H., Removal of chromium (VI) from water and wastewater by using riverbed sand: Effect of important parameters, Journal of Hazardous Materials, 151(2-3), (2008), 789-793

[55]. Srividya, K. and Mohanty, K., Biosorption of hexavalent chromium from aqueous solutions by Catla catla scales: Equilibrium and kinetics studies, Chemical Engineering Journal, 155, (2009), 666-673

[56]. Sudha, B.R. and Emilia, A.T., Biosorption of Cr (VI) from aqueous solution by Rhizopus nigricans, Bioresource Technology, 79, (2001), 73-81

[57]. Suksabye, P., Thiravetyan, P., Nakbanpote, W. and Chayabutra, S., Chromium removal from electroplating wastewater by coir pith, Journal of Hazardous Materials, 141(3), (2007), 637-644

[58]. Tewari, N., Vasudevan, P. and Guha, B.K., Study on Biosorption of Cr (VI) by Mucor hiemalis, Biochemical Engineering Journal, 23(2), (2005), 185-192

[59]. Tunali, S., Kiran, I. and Akar, T., Chromium (VI) biosorption characteristics of Neurospore crassa fungal biomass, Minerals Engineering, 18(7), (2005), 681-689

[60]. Ucun, H., Bayhan, K.Y., Kaya, Y., Cakici, A. and Algur, F O., Biosorption of Cr (VI) from aqueous solution by cone biomass of Pinus sylvestris, Bioresource Technology, 85, (2002), 155-158

[61]. Vinod, V.T.P., Sashidhar, R.B. and Sreedhar, B., Biosorption of nickel and total chromium from aqueous solution by gum kondagogu (Cochlospermum gossypium): A carbohydrate biopolymer, Journal of Hazardous Materials, 178, (2010), 851-860

[62]. Verma, A., Chakraborty, S. and Basu, J.K., Adsorption study of hexavalent chromium using tamarind hull-based adsorbents, Separation and Purification Technology, 50(3), (2006), 336-341

[63]. Wang, X.S., Li, Z.Z. and Tao, S.R., Removal of chromium (VI) from aqueous solution using Walnut hull, Journal of Environmental Management, 90, (2009), 721-729

79

[65]. Agrawal, A. and Sahu, K.K., Kinetic and isotherm studies of cadmium adsorption on manganese nodule residue, Journal of Hazardous Materials, 137, (2006), 915–924

[66]. Aksu, Z., Equilibrium and kinetic modelling of cadmium (II) biosorption by C. vulgaris in a batch system: Effect of temperature, Separation and Purification Technology, 21, (2001), 285-294

[67]. Anayurt, R.A., Sari, A. and Tuzen, M., Equilibrium, thermodynamic and kinetic studies on biosorption of Pb(II) and Cd(II) from aqueous solution by macrofungus (Lactarius scrobiculatus) biomass, Chemical Engineering Journal, 151, (2009), 255-261

[68]. Areco, M.M. and Afonso, M.S., Copper, zinc, cadmium and lead biosorption by Gymnogongrus torulosus, Thermodynamics and kinetics studies, Colloids and SurfacesB: Biointerfaces, 81, (2010), 620-628

[69]. Barka, N., Abdennouri, M., Boussaoud, A. and Makhfouk, M.E., Biosorption characteristics of cadmium (II) onto Scolymus hispanicus L. as low-cost natural biosorbent, Desalination, 258, (2010), 66-71

[70]. Chakravarty, P., Sarma, N.S. and Sarma, H.P., Biosorption of cadmium (II) from aqueous solution using heartwood powder of Areca catechu, Chemical Engineering Journal, 162, (2010), 949-955

[71]. Chen, G., Zeng, G., Tang, L., Dua, C., Jiang, X., Huang, G., Liu, H. and Shen, G., Cadmium removal from simulated wastewater to biomass byproduct of Lentinus edodes, Bioresource Technology, 99, (2008), 7034-7040

[72]. Choi, S.B. and Yeoung-Sang, Y., Biosorption of cadmium by various types of dried sludge: An equilibrium study and investigation of mechanisms, Journal of Hazardous Materials, 138, (2006), 378-383

[73]. Cruz, C. C. V., Da Costa, A.C.A., Henriques, C.A. and Luna, A.S.,

Kinetic modeling and equilibrium studies during cadmium biosorption by dead Sargassum sp. biomass, Bioresource Technology, 91, (2004), 249-257

[74]. Dang, V.B.H., Doan, H.D., Dang-Vu, T. and Lohi, A.,

Equilibrium and kinetics of biosorption of cadmium (II) and copper (II) ions by wheat straw, Bioresource Technology, 100, (2009), 211-219

80

[75]. Fan, T., Liu, Y., Feng, B., Zeng, G., Yang, C., Zhou, M., Zhou, H., Tan, Z. and Wang, X., Biosorption of cadmium (II), zinc (II) and lead (II) by Penicillium simplicissimum: Isotherms, kinetics and thermodynamics, Journal of Hazardous Materials 160, (2008), 655-661

[76]. Gupta, V.K. and Rastogi, A., Equilibrium and kinetic modelling of cadmium (II) biosorption by nonliving algal biomass Oedogonium sp.from aqueous phase, Journal of Hazardous Materials, 153, (2008), 759-766

[77]. Hai-Ping, Y., Jun-Hui, Z., Zhen-Mei, L., Min, H. and Wu, C., Studies on biosorption equilibrium and kinetics of Cd2+ by Streptomyces sp. K33 and HL-12, Journal of Hazardous Materials, 164, (2009), 423-431

[78]. Herrero, R., Lodeiro, P., Rojo, R., Ciorba, A., Rodriguez, P., Manuel, E. and Sastre de Vicente, M.E., The efficiency of the red alga Mastocarpus stellatus for remediation of cadmium pollution, Bioresource Technology, 99, (2008), 4138-4146

[79]. Jyh-Ping, C. and Yung-Sheng, L., Sol-gel-immobilized recombinant E. coli for biosorption of Cd2+, Journal of the Chinese Institute of Chemical Engineers, 38, (2007), 235-243

[80]. Li, Q., Wu, S., Liu, G., Liao, X., Deng, X., Sun, D., Hu, Y. and Huang, Y., Simultaneous biosorption of cadmium (II) and lead (II) ions by pretreated biomass of Phanerochaete chrysosporium, Separation and Purification Technology, 34, (2004), 135-142

[81]. Liu, Y., Cao, Q., Luo, F. and Chen, J., Biosorption of Cd2+, Cu2+, Ni2+ and Zn2+ ions from aqueous solutions by pretreated biomass of brown algae, Journal of Hazardous Materials, 163, (2009), 931-938

[82]. Lodeiro, P., Cordero, B., Barriada, J.L., Herrero, R. and Sastre de Vicente M.E., Biosorption of cadmium by biomass of brown marine macroalgae, Bioresource Technology, 96, (2005), 1796-1803

[83]. Martinez, M., Miralles, N., Hidalgo, S., Fiol, N., Villaescusa, I. and Poch, J., Removal of lead (II) and cadmium (II) from aqueous solutions using grape stalk waste, Journal of Hazardous Materials, 133, (2006), 203-211

[84]. Mashitah, M.D., Azila, Y.Y. and Bhatia, S., Biosorption of cadmium (II) ions by immobilized cells of Pycnoporus sanguineus from aqueous solution, Bioresource Technology, 99, (2008), 4742-4748

81

[85]. Mata, Y.N., Blazquez, M.L., Ballester, A., Gonzalez, F. and Munoz, J.A., Characterization of the biosorption of cadmium, lead and copper with the brown alga Fucus vesiculosus, Journal of Hazardous Materials, 158, (2008), 316-323

[86]. Mathialagan, T. and Viraraghavan, T., Adsorption of cadmium from aqueous solutions by perlite, Journal of Hazardous Materials, 94, (2002), 291-303

[87]. Munagapati, V.S., Yarramuthi, V., Nadavala, S.K., Alla, S.B. and Abburi, K., Biosorption of Cu(II), Cd(II) and Pb(II) by Acacia leucocephala bark powder: Kinetics, equilibrium and thermodynamics, Chemical Engineering Journal, 157, (2010), 357-365

[88]. Ozdemir, G., Ozturk, T., Ceyhan, N., Isler, R. and Cosar, T., Heavy metal biosorption by biomass of Ochrobactrum anthropi producing exopolysaccharide in activated sludge, Bioresource Technology, 90, (2003), 71-74

[89]. Ozdemir, G., Ceyhan, N., Ozturk, T., Akirmak, F. and Cosar, T., Biosorption of chromium (VI), cadmium (II) and copper (II) by Pantoea sp. TEM18, Chemical Engineering Journal, 102, (2004), 249-253

[90]. Ozdemir, S., Kilinc, E., Poli, A., Nicolaus, B. and Guven, K., Biosorption of Cd, Cu, Ni, Mn and Zn from aqueous solutions by thermophilic bacteria, Geobacillus toebii sub.sp., decanicus and Geobacillus thermoleovorans sub.sp. stromboliensis: Equilibrium, kinetic and thermodynamic studies, Chemical Engineering Journal, 152, (2009), 195-206

[91]. Panda, G.C,, Dasm S.K,, Chatterjee, S., Maity, P.B., Bandopadhyay, T.S. and Guha, A.K., Adsorption of cadmium on husk of Lathyrus sativus: Physico-chemical study, Colloids and Surfaces B: Biointerfaces, 50, (2006), 49-54

[92]. Perez-Marin, A.B., Zapata, V.M., Ortuno, J.F., Aguilar, M., Saez, J. and

Llorens, M., Removal of cadmium from aqueous solutions by adsorption onto orange waste, Journal of Hazardous Materials, 139, (2007), 122-131

[93]. Pino, G.H., Luciana Souza de Mesquita, M., Torem, M.L. and Pinto, G.A.S., Biosorption of cadmium by green coconut shell powder, Minerals Engineering, 19, (2006), 380-387

[94]. Rangsayatorn, N., Pokethitiyook, P., Upatham, E.S. and Lanza, G.R., Cadmium biosorption by cells of Spirulina platensis TISTR 8217 immobilized in alginate and silica gel, Environment International 30, 57-63, 2004

82

[95]. Rao, R.A.K., Khan, M.A. and Rehman, F.,

Utilization of Fennel biomass (Foeniculum vulgari) a medicinal herb for the biosorption of Cd (II) from aqueous phase, Chemical Engineering Journal, 156, (2010), 106-113

[96]. Rathinam, A., Maharshi, B., Janardhanan, S.K., Jonnalagadda, R.R. and Nair, B.U., Biosorption of cadmium metal ion from simulated wastewaters using Hypnea valentiae biomass: A kinetic and thermodynamic study, Bioresource Technology, 101, (2010), 1466-1470

[97]. Romera, E., Gonzalez, F., Ballester, A., Blazquez, M.L. and Munoz, J.A., Comparative study of biosorption of heavy metals using different types of algae, Bioresource Technology, 98, (2007), 3344-3353

[98]. Saeed, A., Akhter, M.W. and Iqbal, M., Removal and recovery of heavy metals from aqueous solution using papaya wood as a new biosorbent, Separation and Purification Technology, 45, (2005), 25-31

[99]. Sari, A. and Tuzen, M., Biosorption of Pb (II) and Cd (II) from aqueous solution using green alga (Ulva lactuca) biomass, Journal of Hazardous Materials, 152, (2008), 302-308

[100]. Sari, A. and Tuzen, M., Biosorption of cadmium (II) from aqueous solution by red algae (Ceramium virgatum): Equilibrium, kinetic and thermodynamic studies, Journal of Hazardous Materials, 157, (2008), 448-454

[101]. Sari, A., Mendil, D., Tuzen, M. and Soylak, M., Biosorption of Cd (II) and Cr (III) from aqueous solution by moss (Hylocomium splendens) biomass: Equilibrium, kinetic and thermodynamic studies, Chemical Engineering Journal, 144, (2008), 1-9

[102]. Sari, A. and Tuzen, M.,

Kinetic and equilibrium studies of biosorption of Pb (II) and Cd (II) from aqueous solution by macrofungus (Amanita rubescens) biomass, Journal of Hazardous Materials, 164, (2009), 1004-1011

[103]. Say, R., Denizli, A. and Arica, M.Y., Biosorption of cadmium (II), lead (II) and copper (II) with the filamentous fungus Phanerochaete chrysosporium, Bioresource Technology, 76, (2001), 67-70

[104]. Seker, A., Shahwan, T., Eroglu, A.E., Yilmaz, S., Demirel, Z. and Dalay, M.C., Equilibrium, thermodynamic and kinetic studies for the biosorption of aqueous lead(II), cadmium(II) and nickel(II) ions on Spirulina platensis, Journal of Hazardous Materials, 154, (2008), 973-980

83

[105]. Sheng, P.X., Yen-Peng, T., Chen, J.P. and Hong, L.,

Sorption of lead, copper, cadmium, zinc, and nickel by marine algal biomass: Sargassum sp., Padina sp., Ulva sp., and Gracillaria sp., Characterization of biosorptive capacity and investigation of mechanisms, Journal of Colloid and Interface Science, 275, (2004), 131-141

[106]. Shu-juan, D., De-zhou, W., Dong-qin, Z., Chun-yun, J., Yu-juan, W. and Wen-gang, L., Removing cadmium from electroplating wastewater by waste Saccharomyces cerevisiae, Transactions of Nonferrous Metal Society China, 18(4), (2008), 1008-1013

[107]. Singh, K.K., Rastogi, R. and Hasan, S.H., Removal of cadmium from wastewater using agricultural waste rice polish, Journal of Hazardous Materials, 121, (2005), 51-58

[108]. Taty-Costodes, V.C., Fauduet, H., Porte, C. and Delacroix, A., Removal of Cd (II) and Pb (II) ions, from aqueous solutions, by adsorption onto sawdust of Pinus sylvestris, Journal of Hazardous Materials, 105, (2003), 121-142

[109]. Tuzun, I., Bayramoglu, G., Yalcin, E., Basaran, G., Celik, G. and Arica, M.Y., Equilibrium and kinetic studies on biosorption of Hg(II), Cd(II) and Pb(II) ions onto microalgae Chlamydomonas reinhardtii, Journal of Environmental Management, 77, (2005), 85-92

[110]. Vimala, R. and Das, N., Biosorption of cadmium (II) and lead (II) from aqueous solutions using mushrooms: A comparative study, Journal of Hazardous Materials, 168, (2009), 376-382

[111]. Wei-Chen, K., Jane-Yii, W., Chia-Che, C. and Jo-Shu, C.,

Cadmium biosorption by polyvinyl alcohol immobilized recombinant Escherichia coli, Journal of Hazardous Materials, 169, (2009), 651-658

[112]. Xiao, X., Luo, S.L., Zeng, G., Wei, W., Wana, Y., Chen, L., Guo, H., Cao, Z., Yang, L., Chen, J. and Xi, Q., Biosorption of cadmium by endophytic fungus (EF) Microsphaeropsis sp. LSE10 isolated from cadmium hyperaccumulator Solanum nigrum L., Bioresource Technology 101, (2010), 1668-1674

[113]. Xue-Jiang, W., Si-qing, X., Ling, C., Jian-ful, Z., Jean-marc, C. and Jaffirezic-renault, N., Biosorption of cadmium (II) and lead (II) ions from aqueous solutionsonto dried activated sludge, Journal of Envirnomental Science, 18(5), (2006), 840-844

84

[114]. Yalcinkaya, Y., Soysal, L., Denizli, A., Arica, M.Y., Bektas, S. and Genc, O., Biosorption of cadmium from aquatic systems by carboxymethylcellulose and immobilized Trametes versicolor, Hydrometallurgy 63, (2002), 31-40

[115]. Yun-Guo, L., Ting, F., Guang-ming, Z., Xin, L., Qing, T., Fe, Y., Ming,

Z., Wei-hua, X. and Yu-e, H., Removal of cadmium and zinc ions fi-om aqueous solution by living Aspergillus niger, Transactions of Nonferrous Metal Society China, 16, (2006), 681-686

[116]. Yuh-Shan, H. and Ofomaja, A.E., Biosorption thermodynamics of cadmium on coconut copra meal as biosorbent, Biochemical Engineering Journal 30, (2006), 117-123

[117]. Zhou, W., Wang, J., Shen, B., Hou, W. and Zhang, Y., Biosorption of copper (II) and cadmium (II) by a novel exopolysaccharide secreted from deep-sea mesophilic bacterium, Colloids and Surfaces B: Biointerfaces, 72, (2009), 295-302

[118]. Ziagova, M., Dimitriadis, G., Aslanidou, D., Papaioannou, X., Tzannetaki, E.L. and Liakopoulou-Kyriakides, M., Comparative study of Cd (II) and Cr (VI) biosorption on Staphylococcusxylosus and Pseudomonas sp. in single and binary mixtures, Bioresource Technology 98, (2007), 2859-2865

[119]. Amini, M., Younesi, H. and Bahramifar, N., Biosorption of nickel (II) from aqueous solution by Aspergillus niger: Response Surface Methodology and isotherm study, Chemosphere, 75, (2009), 1483-1491

[120]. Amini, M., Younesi, H. and Bahramifar, N., Statistical modeling and optimization of the cadmium biosorption process in an aqueous solution using Aspergillus niger, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 337, (2009), 67-73

[121]. Azila, Y.Y., Mashitah, M.D. and Bhatia, S.,

Process optimization studies of Pb (II) biosorption onto immobilized cells of Pycnoporus sanguineus using Response Surface Methodology, Bioresource Technology, 99, (2008), 8549-8552

[122]. Can, M.Y., Kaya, Y. and Algur, O.F.,

Response surface optimization of the removal of nickel from aqueous solution by cone biomass of Pinus sylvestris, Bioresource Technology, 97, (2006), 1761-1765

[123]. Cojocaru, C., Diaconu, M., Cretescu, I., Savic, J. and Vasic, V., Biosorption of copper (II) ions from aqua solutions using dried yeast biomass, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 335, (2009), 181-188

85

[124]. Fereidouni, M., Daneshi, A. and Younesi, H., Biosorption equilibria of binary Cd (II) and Ni (II) systems onto Saccharomyces cerevisiae and Ralstonia eutropha cells: Application of Response Surface Methodology, Journal of Hazardous Materials, 168, (2009), 1437-1448

[125]. Ghorbania, F., Younesia, H., Ghasempouri, S.M., Zinatizadeh, A.A., Aminia, M. and Daneshia, A., Application of Response Surface Methodology for optimization of cadmium biosorption in an aqueous solution by Saccharomyces cerevisiae, Chemical Engineering Journal, 145, (2008), 267-275

[126]. Hasan, S.H., Srivastava, P. and Talat, M., Biosorption of Pb (II) from water using biomass of Aeromonas hydrophila: Central Composite Design for optimization of process variables, Journal of Hazardous Materials, 168, (2009), 1155-1162

[127]. Ozer, A., Gurbuz, G., Calimli, A. and Korbahti, B.K., Biosorption of copper (II) ions on Enteromorpha prolifera: Application of Response Surface Methodology (RSM), Chemical Engineering Journal, 146, (2009), 377-387

[128]. Preetha, B. and Viruthagiri, T., Application of Response Surface Methodology for the biosorption of copper using Rhizopus arrhizus, Journal of Hazardous Materials, 143, (2007), 506-510

[129]. Sahu, J.N., Acharya, J. and Meikap, B.C., Response Surface Modeling and optimization of chromium (VI) removal from aqueous solution using Tamarind wood activated carbon in batch process, Journal of Hazardous Materials, 172, (2009), 818-825

[130]. Apiratikul, R. and Pavasant, P., Batch and column studies of biosorption of heavy metals by Caulerpa lentillifera, Bioresource Technology, 99, (2008), 2766-2777

[131]. Aksu, Z. and Gonen, F., Biosorption of phenol by immobilized activated sludge in a continuous packed bed: Prediction of breakthrough curves, Process Biochemistry, 39, (2004), 599-613

[132]. Cabuk, A., Akar, T., Tunali, S. and Tabak, O., Biosorption characteristics of Bacillus sp. ATS-2 immobilized in silica gel for removal of Pb (II), Journal of Hazardous Materials, 136, (2006), 317-323

[133]. Calero, M., Hernainz, F., Blazquez, G., Tenorio, G. and Martin-Lara, M.A., Study of Cr (III) biosorption in a fixed-bed column, Journal of Hazardous Materials, 171, (2009), 886-893

86

[134]. Chen, J-P., Batch and continous adsorption of strontium by plant root tissues, Bioresource Technology, 60, (1997), 185-189

[135]. Chu, K.H. and Hashim, M.A., Copper biosorption on immobilized seaweed biomass: Column breakthrough characteristics, Journal of Environmental Sciences, 19, (2007), 928-932

[136]. Gokhale, S.V., Jyoti, K.K. and Lele, S.S., Modeling of chromium (VI) biosorption by immobilized Spirulina platensis in packed column, Journal of Hazardous Materials, 170, (2009), 735-743

[137]. Hasan, S.H. and Srivastava, P., Batch and continuous biosorption of Cu2+ by immobilized biomass of Arthrobacter sp., Journal of Environmental Management, 90, (2009), 3313-3321

[138]. Hawari, A.H. and Mulligan, C.N.,

Heavy metals uptake mechanisms in a fixed-bed column by calcium-treated anaerobic biomass, Process Biochemistry, 41, (2006), 187-198

[139]. Malkoc, E., Nuhoglu, E. and Abali, Y.,

Cr (VI) adsorption by waste acorn of Quercus ithaburensis in fixed beds: Prediction of breakthrough curves, Chemical Engineering Journal, 119(1), (2006), 61-68

[140]. Malkoc, E. and Nuhoglu, Y., Fixed bed studied for the sorption of chromium (VI) onto tea factory waste, Chemical Engineering Science, 61(13), (2006), 4363-4372

[141]. Mata, Y.N., Blazquez, M.L., Ballester, A., Gonzalez, F. and Munoz, J.A., Optimization of the continuous biosorption of copper with sugar-beet pectin gels, Journal of Environmental Management, 90, (2009), 1737-1743

[142]. Mungasavalli, D.P., Viraraghavan, T. and Yee-Chung, J., Biosorption of chromium from aqueous solutions by pretreated Aspergillus niger: Batch and column studies, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 301, (2007), 214-223

[143]. Pamukoglu, Y. and Kargi, F.,

Biosorption of copper (II) ions onto powdered waste sludge in a completely mixed fed-batch reactor: Estimation of design parameters, Bioresource Technology, 98, (2007), 1155-1162

87

[144]. Perez, M.A.B., Aguilar, M.I., Meseguer, V.F., Ortuno, J.F., Saez, J. and Llorens, M., Biosorption of chromium (III) by orange (Citrus cinensis) waste: Batch and continuous studies, Chemical Engineering Journal, 155, (2009), 199-206

[145]. Preetha, B. and Viruthagiri, T., Batch and Continuous biosorption of chromium (VI) by Rhizopus arrhizus, Separation and Purification Technology, 57, (2007), 126-133

[146]. Sushera, B., Maleeya, K., Prayad, P., Suchart, U. and Lanza, G.R., Batch and continuous packed column studies of cadmium biosorption by Hydrilla verticillata Biomass, Journal of Bioscience and Bioengineerring, 103(6), (2007), 509-513

[147]. Vieira, M.G.A., Oisiovici, R.M., Gimenes, M.L. and Silva, M.G.C., Biosorption of chromium (VI) using a Sargassum sp. packed-bed column, Bioresource Technology, 99, (2008), 3094-3099

[148]. Vijayaraghavan, K. and Prabu, D., Potential of Sargassum wightii biomass for copper (II) removal from aqueous solutions: Application of different mathematical models to batch and continuous biosorption data, Journal of Hazardous Materials, 137, (2006), 558-564

[149]. Vilar, V.J.P., Botelho, C.M.S., Loureiro, J.M. and Boaventura, R.A.R.,

Biosorption of copper by marine algae Gelidium and algal composite material in a packed bed column, Bioresource Technology, 99, (2008), 5830-5838

[150]. Vilar, V.J.P., Santos, S.C.R., Martins, R.J.E., Botelho, C.M.S. and Boaventura, R.A.R., Cadmium uptake by algal biomass in batch and continuous (CSTR and packed bed column) adsorbers, Biochemical Engineering Journal, 42, (2008), 276-289

[151]. Yan, G. and Viraraghavan, T., Heavy metal removal in a biosorption column by immobilized M.rouxii biomass, Bioresource Technology, 78, (2001), 243-249