metal tolerance and sequestration of ni(ii), zn(ii) and cr(vi) ions from simulated and...

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International Biodeterioration & Biodegradation 66 (2012) 82e90

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International Biodeterioration & Biodegradation

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Metal tolerance and sequestration of Ni(II), Zn(II) and Cr(VI) ions from simulatedand electroplating wastewater in batch process: Kinetics and equilibrium study

Rajender Kumar a,*, Divya Bhatia b, Rajesh Singh a, Narsi R. Bishnoi a

aDepartment of Environmental Science and Engineering, Guru Jambheshwar University of Science and Technology, Hisar 125001, Haryana, Indiab Institut Francilien des Sciences Appliquées, Bât. IFI, Université Paris-Est, Marne-la-Vallée, Cedex 2, France

a r t i c l e i n f o

Article history:Received 14 June 2011Received in revised form5 November 2011Accepted 10 November 2011Available online 8 December 2011

Keywords:Filamentous fungiMetal toleranceMinimum inhibitory concentrations (MICs)Isotherms and kineticsSorption mechanisms

* Corresponding author. Tel.: þ91 1662263321.E-mail address: [email protected] (R. Kumar

0964-8305/$ e see front matter � 2011 Elsevier Ltd.doi:10.1016/j.ibiod.2011.11.006

a b s t r a c t

In the present study, total eightfilamentous fungal strainswere isolated frommetal plating effluent dischargedsoil. Among the tested isolates, four fungal strains namely Aspergillus niger, Aspergillus sydoni, Penicillium jan-thinellum and Trichoderma viridewere exhibited greater tolerance toNi(II)> Zn(II)> Cr(VI) ions. Themyceliumgrowth order of the fungal strainswas observed asA. niger> T. viride> A. sydoni> P. Janthinellum. Fungal strainA. niger is the highly tolerant strain and found minimum inhibitory concentration for Cr(VI) 3.5 mg/mL, Ni(II)4.5 mg/mL and Zn(II) 3.0 mg/mL. Maximum dry weight of A. nigerwas observed 4.59 g/L in Cr(VI), 5.09 g/L inNi(II) and 5.01 g/L in Zn(II) ions at initial concentration 50 mg/L in broth medium. Further sorption study wascarried out to sequestration of Ni(II), Zn(II) and Cr(VI) ions from simulated and real electroplating wastewaterwith mycelia of A. niger. The sorption performance was evaluated by equilibrium and kinetic studies. Aftersorption process, the bound metal ions were eluted with 0.1 M HCl solution for reusability of the biosorbent.Functional groups and cell surface morphology were analyzed using Fourier Transform Infrared Spectrometer(FTIR) and Scanning Electron Microscopy (SEM).

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1. Introduction

The presence of toxic heavy metals contamination in aqueousstreams, arising from the discharge of untreated metal-containingeffluent into water bodies, is one of the most important environ-mental issues. The development and implementation of cost-effective process for removal/recovery of metals is essential inorder to improve the competitiveness of industrial processingoperations and to minimize the environmental hazard of toxicmetal-containing effluents (Volesky, 2003). The conventionalmethods i.e. chemical precipitation, electrochemical treatment,reverse osmosis, ion exchange, precipitation (sedimentation,flotation, filtration) involve or capital and operational high costs, orthey are inefficient at low metal concentration (1e100 ppm), orthey can be associated to production of secondary residues thatpresent treatment problems (Aksu, 2001; Ahluwalia and Goyal,2007). Bio-reduction of metals and their mineralization (turningthem into natural deposits) is an attractive low-rate and cost-effective option. Bioaccumulation and biosorption are twoprocesses, one based on the assimilation of metals inside thebiomass and another process is biosorption, in which metallic ions

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remain at the cell surface by different mechanisms (Vijayaraghavanand Yun, 2008). In the concept of biosorption, several chemicalprocesses may be involved, such as adsorption, ion exchange andcovalent bonding with the biosorptive sites of the microorganismsincluding carboxyl, hydroxyl, sulfhydryl, amino and phosphategroups (Frurest and Volesky, 1997; Say et al., 2001; Montazer-Rahmati et al., 2011). The potential of biosorption is very great;for example, it may be used for the purification and recovery of rareproteins, steroids, pharmaceuticals, and drugs that are valued inthousands of dollars per gram (Volesky, 2007). Besides the studieson environmental field of biosorption processes, others applica-tions in the last few years led to developed the recovery of highdemand and/or aggregated value metals such as gold, silver,uranium, thorium, and recently rare earth metals (RE) (Palmieri,2001). For this reason, many biosorption processes are underdevelopment or have been developed and patented for commercialapplications. Selected types of biomass (algae, fungi, bacteria) willrequire different and specific treatment for their optimal formula-tion into finished ready-to-use products for industrial application.Among other biosorption agent, fungi biomasses have a highpercentage of cell wall material that shows excellent metal-bindingproperties. Fungal biomass may be utilized by biosorptiveprocesses as it often exhibits marked tolerance towards metals andother factors such as lowpH (Gadd,1990; Kapoor and Viraraghavan,

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R. Kumar et al. / International Biodeterioration & Biodegradation 66 (2012) 82e90 83

1997; Zafar et al., 2007). The use of dead fungal biomass has beenpreferred in numerous studies for biosorption of toxic metal ionsfrom aqueous solution (Kapoor and Viraraghavan, 1998; Bishnoiand Garima, 2005; Singh et al., 2010). Fungal biomass such asRhizopus (Bai and Abraham, 2001), Aspergillus niger, Penicilliumjanthinellum (Dursun et al., 2003; Kumar et al., 2008), Trichodermaviride (Bishnoi and Kumar, 2006; Kumar et al., 2011) was selectedby many researchers for bioremediation of heavy metal ions. A.niger is a filamentous ascomycete fungus and one of the mostcommon species in the genus Aspergillus. This fungus is commer-cially and economically essential in fermentation for citric acidproduction due to its efficiency and high yield outcome. Since theircell wall surface contained many functional groups of carboxyl,hydroxyl, sulfhydryl and amino groups, having ability to bind metalions (Volesky, 2003). There are limited studies that have beenconducted to screening of metal tolerance fungi from polluted sitefrom their diversity, tolerance study, fungal mycelia growth inmetal accumulation medium, screening among the several isolatedstrains, reusability and sorption mechanisms study. Taking theseaspects in consideration, the main aim of this study was to find outthe metal tolerant strains and determine the sorption capacity ofCr(VI), Zn(II) and Ni(II) ions from simulated and real wastewater.The equilibrium and kinetic study was done to understand thesorption process. Sorptionedesorption study was analyzed toachieve sorption or desorption equilibrium and reusability of thebiosorbent. Surface morphology and functional groups involved inbiosorption process were confirmed using Fourier transforminfrared spectroscopy (FTIR) and scanning electron microscopy(SEM).

2. Materials and methods

2.1. Isolation and identification of fungal strains

Standard spread plate method was performed for isolation offungal strains from soil and sludge samples of the electroplatingindustrial wastewater. For isolation of fungal colonies, 20 mLmediaamended with 100 mg/L of Cr(VI), Ni(II) and Zn(II) ions were takeninto petriplates. The detailed process for the isolation and purifi-cation has already been described in previous study (Kumar et al.,2008). Isolated metal resistant strains were identified on thebasis of morphological, physiological and biochemical characteris-tics from Indian Agricultural Research Institute (IARI), New Delhiand Microbial Type Culture Collection (MTCC), Institute of Micro-bial Technology, Chandigarh.

2.2. Determination of MICs

Heavy metals tolerance assay was performed to determine theMinimum Inhibitory Concentration (MICs) for isolated fungalstrains. The metals Cr(VI), Ni(II) and Zn(II) ions were used asK2Cr2O7, NiSO4 and ZnSO4 in varying concentration ranging from0.05 to 5.0 mg/mL. The strain was maintained on solid Rose Bengalagar medium and composition was mentioned in earlier study(Kumar et al., 2008).

2.3. Fungal mycelium growth

The screened fungal strain was grown in 250 mL Erlenmeyerflasks containing 100 mL of potato dextrose liquid medium. Themediumwas amended with progressively increasing concentrationof heavy metals (0, 5, 10, 15, 20, 25 and 50 mg/L) of Cr(VI), Ni(II),Zn(II) ions. The accumulation medium was prepared with heavymetals (i.e. sterilized separately) and containing other ingredients.The pH of final solution was adjusted 5.0 by using sterile HNO3 or

NaOH solutions. The 7 days old cultures were inoculated intomedium and incubated at 30 �C on an orbital shaker at 150 rpm for72 h. After 72 h, the biomass was harvested by filtration througha 150 mm sieve and dried to obtain constant weight at 105 �C.

2.4. Batch sorption studies

For experimental purpose, inactivated dead fungal myceliaA. niger was used for biosorption study. For optimization of pH,experiments were conducted with varying pH from 2.0 to 8.0 atconcentration 20 mg/L of Cr(VI), Zn(II) and Ni(II) ions, 1.0 g/L ofbiosorbent dose in 50 mL metal solution and contact time 60 min.pH was adjusted using 0.1 M HCl or 0.1 M NaOH solution. Effect ofcontact time was studied from 15 to 120 min at optimum pH fromabove experiments. The effect of the initial Cr(VI), Zn(II) and Ni(II)ions concentration on the biosorption was studied with varyingmetal ions concentration from 10 to 60 mg/L at optimum pH andcontact time from above experiments. All optimization experi-ments were performed with 50 mL synthetic sample in 250 mLconical flasks at 150 rpm. At optimized conditions, removal ofheavy metals from electroplating wastewater was also studied.Concentration of Ni(II) and Zn(II) ions was determined by atomicabsorption spectrophotometer (GBC-932 plus) and Cr(VI) using 1,5diphenyl carbazide method with spectrophotometer at 540 nm.The amount of heavy metal ions adsorbed by the biomass wascalculated using the following equation

q ¼ nðC0 � CeÞM

(1)

where q is the amount of heavy metal ions adsorbed by biomass(mg/g), Co is the initial concentration of metal ion (mg/L), Ce is theconcentration of heavy metal ions at equilibrium (mg/L), and v isthe volume of the metal solution (L) and M is the weight ofadsorbent (g). All the experiments were conducted in triplicate andmean value used in analyzing the data.

Whereas, biosorption efficiency was calculated using followingequation

% Efficiency ¼ ðC0 � CeÞC0

� 100 (2)

2.5. Equilibrium isotherm and kinetic models

Langmuir and Freundlich were used for single solute systems todescribe the biosorption equilibrium and mechanism of metal ionbiosorption. Pseudo-first and second order rate equations wereused to investigate the kinetics of metal sorption by biosorbents.

2.5.1. Freundlich and Langmuir isothermsThe general Freundlich equation is as follows

qe ¼ KfC1=ne (3)

The logarithmic form of the equation is given below

log qe ¼ ð1=nÞlog Ce þ log Kf (4)

Langmuir model can be described as

qe ¼ Q0$b$Ce1þ b$Ce

(5)

The logarithmic form of the equation is given below

1qe

¼ 1Q0

þ 1bQ0

�1Ce

�(6)

Table 1Minimum inhibitory concentration (MICs) for isolated fungal strains.

Fungal strains Minimum inhibitory concentration(MICs) (mg/mL)

Cr(VI) Ni(II) Zn(II)

Aspergillus niger 3.5 4.5 3Aspergillus haterromorphus 0.2 0.5 0.6Aspergillus sydoni 1.8 3.5 2Aspergillus flavus 0.5 1.2 0.7Aspergillus fumigatus 0.4 0.7 0.5Trichoderma viride 1.5 2.5 2.0P. Janthinellum 1.2 2.0 1.5P. fusarium 0.3 0.7 0.2

R. Kumar et al. / International Biodeterioration & Biodegradation 66 (2012) 82e9084

where qe is the uptake of metal per unit weight of biosorbent(mg/g), Ce is the equilibrium concentration of metal ions in solu-tion (mg/L), Kf is the Freundlich constant denoting adsorptioncapacity (mg/g) and n is the empirical constant, is a measure ofadsorption intensity (L/mg). Q0 and b are the Langmuir constantswhich denotes the moles of solute sorbed per unit weight ofadsorbent (mg/g) and affinity between the biosorbents and bio-sorbate (L/mg).

2.5.2. Pseudo-first order and pseudo-second order kineticsThe linear forms of pseudo-first order (Eq. (7)) and pseudo-

second order (Eq. (8)) kinetics models can be described asPseudo-first order rate equation (Lagergren, 1898) is given as

logðqe � qtÞ ¼ logðqeÞ � KL

2:303(7)

Pseudo-second order kinetics (Ho et al., 2002) which is representedby

tq¼ 1

K2q2eþ 1qe

t (8)

where qe is amount of metal adsorbed (mg/g) at equilibrium time,qt is amount of metal ions adsorbed (mg/g) at any time t, KL isLagergren rate constant for adsorption (mg/g/min) and K2 ispseudo-second order rate constant (mg/g/min).

2.5.3. Intraparticle mass transfer diffusion modelAccording to this model, the initial rate of intraparticle diffusion

is calculated by linearization of curve.

q ¼ Kp$t0:5 (9)

where q is amount of adsorbed metal ion on the biomass at time t(mg/g), t is time (min0.5), Kp is related to diffusion coefficient in thesolid (mg/gmin0.5). Thus Kp (mg/gmin0.5) value can be obtainedfrom the slope of the plot of q (mg/g) vs t0.5 (min0.5).

2.6. Desorption and reusability studies

Consecutive sorptionedesorption cycles were repeated fivetimes using the same biosorbent in solution containing with Cr(VI),Zn(II) and Ni(II) ions. After adsorption process, the bound metalions were eluted with 0.1 M HCl solution. The eluted biosorbentwas washed repeatedly with deionized water to remove anyresidual desorbing solution and placed into metal solution for nextbiosorption cycles. All data represent the mean of three indepen-dent experiments, standard deviations and error bars being indi-cated as appropriate in the following section. Desorption efficiencywas calculated by using following equation (Tunali et al., 2005):

Desorption efficiency ¼ Amount of metal ions desorbedAmount of metal ions adsorbed

�100

(10)

2.7. Surface characterization

For the FTIR study,1.0 mg fine particle of the biomass withmetalloaded Cr(VI), Zn(II) and Ni(II) ions and unloaded was encapsulatedin 300 mg of KBr in order to prepare the translucent sample disks.An infrared spectrum was obtained using PerkineElmer FTIR-1600spectrophotometer at spectral range from 4000 to 400 cm�1. SEManalysis was carried out to confirm the identification of metal ionson the biomass and how metal ions would alter the cell surface

morphology. Fungal mycelia biomass was dried at 110 �C and itsmorphology and the metal distribution on the mycelia surface wasanalyzed using Scanning Electron Microscopy (JEOL Model JMS e

6100).

3. Results and discussions

3.1. Screening and metal tolerance study

Total eight fungal strains were identify and selected for thedetermination of Minimum Inhibitory Concentration (MICs).Among the isolates, four strains namely A. niger, Aspergillus sydoni,P. janthinellum and T. viride were exhibited greater tolerance to allmetals ions compare to other isolates (Table 1). A. niger was thehighly tolerant and found minimum inhibitory concentration forCr(VI) 3.5 mg/mL, Ni(II) 4.5 mg/mL and Zn(II) 3.0 mg/mL respec-tively. Sequence of metal tolerance for other strains was Ni(II)>Zn(II)> Cr(VI), it may be due to higher concentration of Ni(II) andZn(II) than Cr(VI) in the contaminated environment and longexposure indicated the high tolerance of fungal isolates. Fromprevious study, the Cr-resistant Aspergillus sp. exhibited greatertolerance when treated with chromium. Cr-resistant Aspergillus sp.survived to a maximum level of 10,000 mg/L of Cr(VI). Chromium-resistantMicrococcus sp. also survived to a concentration 8000 mg/L of Cr(VI) (Congeeveram et al., 2007). Similar results were obtainedfor Trametes versicolor for removal of Cu(II), Pb(II) and Zn(II) (Gulayet al., 2003).

3.2. Growth of mycelia in metal-containing medium

Effect of metal ions concentration on growth of fungal biomass(dryweight g/L) was observedwith increases ions concentrations ofCr(VI), Ni(II), Zn(II) ions from 0 to 50 mg/L (Fig. 1AeC). It wasobserved that fungal mycelia biomass was increased with increasesin concentrations of Cr(VI), Ni(II), Zn(II) ions from 0 to 50 mg/L.Maximum dry weight (g/L) of fungal biomass of. A. niger, T. viride,A. sydoni and P. janthinellumwas observed 4.59, 4.14, 3.89 and 3.74in Cr(VI), 5.09, 5.04, 4.94 and 4.92 in Ni(II) and 5.01, 4.95, 4.53 and4.20 in Zn(II) ions at 50 mg/L concentration. This clearly indicatedthat the higher growthwas in Ni(II) and Zn(II) than Cr(VI) ions in thesolution and order of growth of the fungal strains in different metalionswas observed as A. niger> T. viride> A. sydoni> P. janthinellum.From the present investigation, it was found that the slowgrowth ofmycelia at lower concentration of metal ions in medium andvigorous growth after increasing metal ions concentration indi-cated that these strainsA. niger, T. viride,A. sydoni and P. janthinellumare important in bioremediation of heavy metal contaminatedwastewater.

A

0

1

2

3

4

5

6

0 5 10 15 20 25 50

Cr (VI) ion concentration

Dry w

eig

ht (g

/L)

A.niger A. sydoni

T. viride P. Janthinellum

B

0

1

2

3

4

5

6

0 5 10 15 20 25 50

Ni (II) ion concentration (mg/L)

Dry

we

igh

t (

g/L

)

C

0

1

2

3

4

5

6

0 5 10 15 20 25 50

Zn (II) ions concentration (mg/L)

Dry w

eig

ht (g

/L

)

Fig. 1. Dry weight (g/L) of fungal biomass amended with different concentration ofmetal ions (A) Cr(VI), (B) Ni(II) and (C) Zn(II) ions at temperature 30 �C, pH 5.0 after72 h.

A

0

5

10

15

20

25

1 2 3 4 5 6 7 8

pH

Up

take c

ap

acit

y (

mg

/g)

Cr (VI) Ni (II) Zn (II)

B

0

5

10

15

20

25

15 30 45 60 75 90 105 120

Time (min)

Up

take c

ap

acit

y (

mg

/g)

Cr (VI) Zn (II) Ni (II)

C

5

15

25

35

45

55

10 20 30 40 50 60

Initial concentration of metal ions (mg/L)

Up

atake

cap

acit

y (m

g/g

)

10

30

50

70

90

110

% R

em

oval



Fig. 2. Effect of parameters (A) pH, (B) contact time and (C) initial metal ionsconcentration on sorption of heavy metal by inactivated fungal biomass sp. A. niger.Note: (.) % removal and (d) Uptake capacity (mg/g).


3.3. Biosorption study

3.3.1. Effect of varying pHHeavymetal sorption is highly pH dependent. Solution pH affects

both cell surface metal-binding sites and metal chemistry in water.The maximum uptake capacity of Cr(VI), Zn(II) and Ni(II) ions wasfound 18.37� 0.76 mg/g at pH 2.0, 16.17� 0.53 mg/g at pH 4.0 and16.70� 0.46 mg/g at pH 5.0, respectively (Fig. 2A). Maximumremoval of Cr(VI) was found at pH 2.0 and a sharp decline inadsorption was occurred at pH 4.0. The Cr(VI) exists in differentforms such as H2CrO4, HCrO4

�, CrO42� and Cr2O7

2� in aqueous solution

and the stability of these forms is dependent on thepHof the system.Decrease in solution pH caused formation of more polymerizedchromium oxide species such as Cr3O10

2� and Cr4O132� (Bai and

Abraham, 2001; Kumar et al., 2008). At pH range 2.0e6.0, HCrO4�

and Cr2O72� ions are in equilibrium and above pH 8.0, CrO4

2� is onlyspecies that can exist in solution (Mor et al., 2002). Levankumar et al.(2009) also observed that the active form of Cr(VI) adsorbed on theadsorbent is HCrO4

�. This form is stable at only lower pH range. Butthe concentration of this form decreases when there is anincrease in pH. The optimum pH of the medium was also reportedto be 2.0 for Cr(VI) adsorption using Streptococcus equisimilis,

A

0

5

10

15

20

25

2 3 4 5 6 7 8 9 10 11 12

T0.5

Up

take c

ap

acit

y (m

g/g

)


B

-1.5

-1

-0.5

0

0.5

1

1.5

0 20 40 60 80 100 120

Time (min)

log

(q

e-q

t)


C

0

1

2

3

4

5

6

7

0 50 100 150

Time (min)

t/q

e


Fig. 3. Sorption kinetics plots (A) intraparticle mass transfer diffusion, (B) pseudo-firstorder kinetics and (C) pseudo-second order kinetics.


Saccharomyces cerevisiae and A. niger (Sharma and Forster, 1995;Goyal et al., 2003). Uptake of Zn(II) ions by fungal biomassincreased with increasing pH from 2.0 to 4.0. This may be attributedto fact that as pH increased, more negatively charged cell walllegends exposed and hence increase in attraction for positivelycharged metal occurred (Delgado et al., 1998). At low pH values, therecoveries were found to be low due to binding of Hþ ions and athigher pH, OH� ions compete with Ni(II) ions for active sites on thesurface of adsorbent. Decrease in biosorption at higher thanpH 6.0 isdue to formationof soluble hydroxyl complexes (Kalyani et al., 2003).

3.3.2. Determination of equilibrium timeThe biosorption rate of Cr(VI), Zn(II) and Ni(II) ions by A. niger at

varying contact time 15e120 min is shown in Fig. 2(B). It is evidentfrom the plot that the maximum uptake of Cr(VI), Zn(II) and Ni(II)was reached within 60 min. At equilibrium, the uptake of Cr(VI),Zn(II) and Ni(II) was 18.00� 0.16 mg/g, 17.22� 0.14 mg/g and17.12� 0.151 mg/g respectively at metal ions concentration of20 mg/L fungal dose of 1.0 g/L at optimum pH. Adsorption has beenslowed down in later stages because initially a large number ofvacant surface sites may be available for adsorption and after sometime, the remaining vacant surface sites may be difficult to occupydue to repulsive forces between the solute molecules of the solidand bulk phase (Saravanane et al., 2002; Bishnoi and Kumar, 2006;Singh et al., 2010). Similar observations have also been reportedthat the metal uptake rate was high at initial period of agitationwith different biosorbents (Donmez and Aksu, 2002).

3.3.3. Influence of metal ions concentrationThe experiments were performed at various concentrations

ranging from 10 to 60 mg/L of Cr(VI), Zn(II) and Ni(II) ions andbiosorption capacity and percent removal are shown in Fig. 2(C). Itwas observed that the uptake capacity (mg/g) was increased,whereas, percent removal decreased with increasing metal ionsconcentration from 10 to 60 mg/L. The maximum percent removalwas observed i.e. 99.03 of Cr(VI), 93.15 of Zn(II) and 97.35 of Ni(II)ions at low metal ions concentration at 10 mg/L. The percentremoval was decreased as initial concentration of metal ionsincreased because at higher concentration, number of ionscompeting for the available binding sites whereas, at low concen-tration more binding sites are available for complexation of ions(Bishnoi and Garima, 2005). However, maximum adsorptioncapacity of Cr(VI), Ni(II) and Zn(II) ions was 40.80�1.301 mg/g,33.63� 0.365 mg/g and 33.03� 0.806 mg/g at higher concentra-tions of metal ions at 60 mg/L. The increase of loading capacity ofbiosorbents with increase of metal ions concentration can beattributed to higher probability of interaction between metal ionsand biosorbents (Ozturk et al., 2004; Singh et al., 2011). As high ionsconcentration enhanced mass transfer driving force and increasedmetal ions sorbed per unit weight of adsorbent at equilibrium. Inaddition, increasing metal ions concentration increased number ofcollisions between metal ions and sorbent, which enhanced thesorption process (Bai and Abraham, 2001).

3.4. Equilibrium isotherms and kinetics

3.4.1. Intraparticle mass transfer diffusion modelThrough intraparticle diffusion, a graph plotted between metal

ions adsorbed and square root of time gave a linear curve whichconfirms the occurrence of process of intraparticle diffusion(Fig. 3A). The two phases in the intraparticle diffusion plot suggestthat the sorption process proceeds by surface sorption and intra-particle or pore diffusion. The slope of linear portion of respectiveplots gave the rate constant for intraparticle diffusion representedby ‘KP’. The value of diffusion rate constant (Kp) is 1.0038 mg/g

min0.5 for Cr(VI), 0.8998 mg/g min0.5 for Zn(II) and 0.8309 mg/gmin0.5 for Ni(II) respectively (Table 2). The value of diffusion rateconstant Kp and correlation regression coefficient (r2� 0.95) indi-cated that the sorption of metal ions were higher with fungalbiomass A. niger. On the other hand, the intercept of the plot reflectsthat the boundary layer effect shown in Table 2 is larger theintercept value, the greater the contribution of the surface sorption.The intercepts originate from collision of linear portion of plots aredirectly proportional to the extent of boundary layer thickness(Khatri et al., 1999).

Table 2Sorption dynamics model intra-particle diffusion, pseudo-first order and pseudo-second order model constants.

Metal Intra-particle diffusion constants Pseudo-first order constants Pseudo-second order constants

Kp (mg/gmin0.5) Intercept R2 qe (mg/g) experimental qe (mg/g) calculated KL (mg/g/min) R2 qe (mg/g) calculated K2 (mg/g/min) R2

Cr(VI) 1.0038 10.848 0.940 19.23 14.35 0.043 0.970 20.83 0.0049 0.999Zn(II) 0.8998 9.7809 0.943 18.93 12.62 0.039 0.985 20.66 0.0048 0.999Ni(II) 0.8309 8.5061 0.955 18.75 15.60 0.037 0.967 20.92 0.0035 0.998

A

0

0.5

1

1.5

2

2.5

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2

logCe

log

qe

Cr Zn Ni

B

0.05

0.06

Cr Ni Zn


3.4.2. Pseudo-first order and second order kineticsFig. 3(B) and (C) shows the fitting of data in Lagergren first order

and Pseudo-second order kinetics models. The values of Kad, K2, qeand R2 were obtained from the slope and intercept of the plotsshown in Table 2. Pseudo-first order rate constant Kad is 0.038 mg/g/min for Cr(VI), 0.039 mg/g/min for Zn(II) and 0.037 mg/g/min forNi(II) with A. niger and value of correlation coefficient R2> 0.90indicated the fitness of the data in the model. The value ofadsorption Pseudo-second order rate constant K2 is 0.0049 mg/g/min for Cr(VI), 0.0048 mg/g/min for Zn(II) and 0.0035 mg/g/min forNi(II) and also have high value of correlation coefficient (r2� 0.99)for the Cr(VI), Zn(II) and Ni(II) ions also indicated its better fitness ofdata. The calculated qe value obtained from pseudo-first orderkinetics plot compared with the experimental values of qe, is notshowing good relationship than calculated values of qe obtainedfrom Pseudo-second order kinetic plot (Table 2). It was indicatedthe better fitness of pseudo-second order model in the data. Similarobservations have also been reported that the entire sorptionperiod, pseudo-second order expression better predicts the sorp-tion kinetics than the pseudo-first order model (Bulgariu andBulgariu, 2011).

3.4.3. Adsorption isothermsThe equilibrium data on Cr(VI), Zn(II) and Ni(II) adsorption at

optimum conditions were fitted into Freundlich and Langmuirisotherms model (Fig. 4A, B). Freundlich constants and Langmuirconstants are shown in Table 3. The value of Freundlich constants Kfand 1/n was found by plotting the graph between log qe vs log Ceand yields a linearized form (Fig. 4A). Higher value of Kf and n, wereindicated better adsorption of Cr(VI), Zn(II) and Ni(II) ion withA. niger. The value of Langmuir constants Q0 and b was obtainedfrom fitting the experimental data into Langmuir isotherms model.This data showed higher value of Q0 i.e. 17.51 mg/g for Cr(VI),11.07 mg/g for Zn(II) and 6.24 mg/g for Ni(II) respectively and lowervalue of b also indicated better adsorption capacity. The view ofhigh value of correlation coefficients (r2> 0.90), adsorption data ofCr(VI), Zn(II) and Ni(II) are best fitted in both Freundlich andLangmuir models (Table 3). These values indicate that there isa strong positive relationship in the data. The high value of Kf

indicates a high adsorption capacity. This is defined as the adsor-bate adsorbed per unit weight of adsorbent. Higher the n (n> 1)value, higher is the intensity of adsorption (Hasar, 2003).

0

0.01

0.02

0.03

0.04

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

1/Ce

1/q

e

Fig. 4. Equilibrium sorption isotherm curves (A) Freundlich and (B) Langmuirisotherms.

3.5. Desorption and reuse

Regeneration of the biosorbent and concentration of the metalsolution for eventual recovery further increase the cost effective-ness of the process (Volesky and Naja, 2005). The use of mineralacids as an elutant has been widely studied (Akthar et al., 1995;Kapoor and Viraraghavan, 1996). The desorption efficiency ofCr(VI), Zn(II) and Ni(II) ions was observed �96% with A. niger inconsecutive five cycles using mineral acids (0.1 N HCl) as elutantFig. 5(a)e(c). Similarly the desorption of the adsorbed Cd(II) andCu(II) ions was higher than 95% with 10 mM HCl elutent on inac-tivated B. cinerea (Akar and Tunali, 2005).

3.6. Removal of electroplating wastewater

All the optimum conditions observed from above experimentswere applied to effluent from electroplating industry. Theconcentration of metal ions Cr(VI), Ni, Zn, Cu, Pb and Fe in thesample of electroplating wastewater was observed 34, 190, 24, 1.02,2.5 and 2.6 mg/L. Removal of Cr(VI) ions from electroplatingindustrial wastewater was observed higher than Zn(II) and Ni(II)ions from electroplating wastewater samples. Removal of Cr(VI)was 73.21%, 68.35% Zn(II) and 70.21% of Ni(II). The biosorption ofheavymetals ions fromwastewater samplewas less as compared tosynthetic sample because the presence of other metal ions like Cu,Pb and Fe and other co-ions i.e. sodium, potassium, sulphate andphosphate in wastewater which occupies the adsorption sites andtherefore lesser Cr(VI), Zn(II) and Ni(II) removal occurred. Industrialwastewater usually contains respectable amounts of differentanions that influence the biosorption processes (Filipovic-Kovacevic et al., 2000). Extent of reduction depends upon the

Table 3Sorption isotherms Freundlich and Langmuir constants.

Metal ions Freundlich constants Langmuir constants

r2 Kf (mg/g) n r2 Qo (mg/g) b (L/mg)

A. niger Cr(VI) 0.99 17.92 1.18 0.98 17.51 0.0025Zn(II) 0.98 9.44 0.96 0.97 11.07 0.006Ni(II) 0.97 7.81 0.91 0.98 6.24 0.0021


type and concentration of other cations increased leads to decreasein metal uptake (Kuyucak and Volesky, 1989). A fixed quantity ofbiomass can only offer a finite number of surface binding sites,some of which would be expected to saturate by the competingmetal ions.

3.7. Surface characterization

3.7.1. FTIR analysisThe FTIR spectra were taken to obtain information on nature of

possible cell-metal ions interactions of metal loaded and unloadedbiomass in the range of 4000e400 cm�1. The FTIR spectroscopic

a

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Fig. 5. Adsorptionedesorption cycles for biosorption of metal ions (a) adsorp-tionedesorption of Cr(VI), (b) adsorptionedesorption of Zn(II) and (c) adsorp-tionedesorption of Ni(II) ions.

analysis of metal loaded biomass shifted strong asymmetricalstretching bands as shown in Fig. 6. The FTIR spectra of nativebiomass and shifted broad band after metal loaded biomass withCr(VI), Ni(II) and Zn(II) displayed a number of adsorption peaks areshown in Table 4. These groups are of the bonded amino groups(eNH), hydroxyl groups (OH), carboxylate anions (COO�) andcarboxyl groups (eCO). The difference between three peaks (D)ranged from 31.4, 18.9 and 58 cm�1 for after Cr(VI) sorption, 30,20.9 and 58.7 cm�1 for Ni(II) sorption and 72.3, 25.8, 58 cm�1 forZn(II) sorption. There are also clearly difference in intensity at1652 cm�1 and 1541 cm�1 indicative of carboxylate and sulphateions peaks and others at 1033 cm�1 indicative of phosphate groupsabsorption (P]O) stretching. These results were indicated theinvolvement of the functional groups in biosorption process. FTIRspectral analysis of dried Neurospora crassa biomass indicatedshifted broad bands at 3346, 1645 and 1408 cm�1 when Cr(VI)loaded biomass showed same adsorption at 3409, 1658, and1379 cm�1 (Tunali et al., 2005).

Fig. 6. Infrared spectra of fungal biomass A. niger (a) before metal sorption, (b) afterCr(VI) loaded biomass, (c) after Ni(II) loaded biomass and (d) after Zn(II) loadedbiomass.

Table 4IR adsorption band and corresponding functional groups.

Biomass beforeand after

Bonded-OH,eNH stretching

Aliphaticchain eCH

AsymmetricC]O

Amide II CeO stretchCOOH

CeOH (alcohol)P]O stretching

N-containingbiolegands

Before 3307.7 2343.4 1652.9 1541 1319.2 1033 669.3Cr(VI) 3276.3 (31.4) 2362.3 (18.9) 1650.3 (2.6) 1552 (11.0) 1377.2 (58) 1035 (2.0) 532.4 (136.9)Zn(II) 3380 (72.3) 2369.2 (25.8) 1653.9 (1.0) 1545.4 (4.4) 1377.2 (58.0) 1033 549.5 (119.8)NI(II) 3277.7 (30.0) 2364.3 (20.9) 1653.8 (0.9) 1544.8 (3.8) 1377.9 (58.7) 1035.1 (2.1) 554.1 (115.2)

Note: Value in parenthesis indicates the difference between peaks before and after biosorption.

Fig. 7. Typical SEM micrograph of fungal biomass A. niger (A) Ni(II) loaded biomass, (B) Cr(VI) loaded biomass, (C) Zn(II) loaded biomass and (D) before metal loaded biomass.


3.7.2. SEM analysisThe SEM micrographs of heavy metals free and metal loaded

fungal biomass are shown in Fig. 7. It was observed the cell surfacemorphology considerably changed after metal biosorption. Thesemicrographs were clearly indicated the presence of new shinybulky particles over the surface of metal loaded fungal biomasscells and loaded cells looked vague, distorted and seemed to bedamaged by the heavy metal ions. The alteration in morphologymay also result from the secretion of extra cellular polymericsubstance during metal biosorption of zinc and copper by Desul-fovibrio desulfuricans (Chen et al., 2000).

4. Conclusions

From this investigation it was concluded that A. niger fungalstrain isolated frommetal-polluted environmental is a highlymetaltolerant strain and remove toxic metal Cr(VI), Ni(II) and Zn(II) ionsfrom aqueous solution as well as from electroplating wastewater.The solution of pH is an important parameter for the biosorptionprocess and found optimum pH 2.0 for Cr(VI), 4.0 for Zn(II) and 5.0for Ni(II) ions in batch process. Both kinetics models first order andsecond order are well fitted in data of Cr(VI), Ni(II) and Zn(II) ions.The biosorption of Cr(VI), Ni(II) and Zn(II) by fungal biomass couldbe explained also satisfactorily by the Freundlich and Langmuir

isotherms. FTIR and SEM analysis give better understanding ofsorption mechanism. The desorption efficiency of metal ions wasobtained �97% with 0.1 N HCl, proved quite effective to desorbmetal ions and make the process more economically viable, energysaving and environmentally safe.

References

Ahluwalia, S.S., Goyal, D., 2007. Microbial and plant derived biomass for removal ofheavy metals from wastewater. Bioresource Technology 98, 2243e2257.

Akar, T., Tunali, S., 2005. Biosorption performance of Botrytis cineria fungal byproduct for removal of Cd(II) and Cu(II) ions from aqueous solutions. MineralsEngineering 18, 1099e1109.

Aksu, Z., 2001. Equilibrium and kinetic modeling of cadmium (II) biosorption byC. vulgaris in a batch system: effect of temperature. Separation and PurificationTechnology 21, 285e294.

Akthar, M.N., Sastry, K.S., Mohan, P.M., 1995. Biosorption of silver ions by processedAspergillus niger biomass. Biotechnology Letters 17, 551e556.

Bai, S.R., Abraham, T.E., 2001. Biosorption of Cr(VI) from aqueous solution byRhizopus nigricans. Bioresource Technology 79, 73e81.

Bishnoi, N.R., Garima, 2005. Fungus. An-alternative for bioremediation of heavymetal containing wastewater, a review. Journal of Scientific and IndustrialResearch 64, 93e100.

Bishnoi, N.R., Kumar, R., 2006. Removal of Cr(VI) with Trichoderma viride immobi-lized fungal biomass and cell free Ca-alginate beads. In the Proceedings of theSecond IASTED International Conference on Advanced Technology in Environ-mental Field (ATEF), Lanzarote, Spain.

Bulgariu, D., Bulgariu, L., 2011. Equilibrium and kinetics studies of heavy ions bio-sorption on green algae waste biomass. Bioresource Technology. doi:10.1016/j.biortech.2011.10.016.


Chen, B.Y., Utgikar, V.P., Harmon, S.M., Tabak, H.H., Bishop, D.F., Govind, R., 2000.Studies on biosorption of zinc(II) and copper(II) on Desulfovibrio desulfuricans.International Biodeterioration and Biodegradation 46, 11e18.

Congeeveram, S., Dhanarani, S., Park, J., Dexilin, M., Thamaraiselvi, K., 2007. Bio-sorption of chromium and nickel by heavy metal resistant fungal and bacterialisolates. Journal of Hazardous Material 146, 270e277.

Delgado, A., Anselmo, A.M., Novais, J.M., 1998. Heavy metal biosorption by driedmycelium of Fusarium flocciferum. Water Environmental Research 70, 370e375.

Donmez, G.C., Aksu, Z., 2002. Removal of chromium (VI) from saline wastewaters byDunaliella species. Process Biochemistry 38, 751e762.

Dursun, A.Y., Ulsu, G., Cuci, Y., Aksu, Z., 2003. Bioaccumulation of Copper (II), Lead(II) and Chromium (VI) by growing Aspergillus niger. Process Biochemistry 38,1647e1651.

Filipovic-Kovacevic, Z., Sipos, L., Briski, F., 2000. Biosorption of chromium, copper,nickel and zinc ions onto fungal pellets of Aspergillus niger 405 from aqueoussolutions. Food Technology and Biotechnology 38, 211e216.

Frurest, E., Volesky, B., 1997. Alginate properties and heavy metal biosorption bymarine algae. Application of Biochemistry and Biotechnology 67, 215e226.

Gadd, G.M., 1990. Fungi and yeast metal accumulation. In: Ehrlich, H.L., Brierley, C.L.(Eds.), Microbial Mineral Recovery. McGraw Hill, New York, pp. 249e276.

Goyal, N., Jain, S.C., Banerjee, U.C., 2003. Comparative studies on the microbialadsorption of heavy metals. Advances in Environmental Research 7, 311e319.

Gulay, B., Sema, B., Yakub, A.M., 2003. Biosorption of heavy metal ions on immo-bilized white rot fungus Trametes versicolor. Journal of Hazardous Material 101,285e300.

Hasar, H., 2003. Adsorption of nickel(II) from aqueous solution onto activatedcarbon prepared from almond husk. Journal of Hazardous Material 97, 49e57.

Ho, Y.S., Huang, C.T., Huang, H.W., 2002. Equilibrium sorption isotherm for metalion on tree fern. Process Biochemistry 37, 1421e1430.

Kalyani, S., Priya, P.A., Rao, P.S., Krishnaiah, A., 2003. Adsorption of nickel on flyashin natural and acid treated forms. Indian Journal of Environmental Health 45,163e168.

Kapoor, A., Viraraghavan, T., 1996. Biosorption of heavy metals on fungal biomass.In: Proceedings of the 4th CSCE Environmental Engineering Specialty Confer-ence, Edmonton, Alberta, pp. 333e343.

Kapoor, A., Viraraghavan, T., 1997. Heavy metal biosorption sites in Aspergillus niger.Bioresource Technology 61, 221e227.

Kapoor, A., Viraraghavan, T., 1998. Biosorption of heavy metals on Aspergillus niger:effect of pretreatment. Bioresource Technology 63, 109e113.

Khatri, J.I.S., Sarma, T.A., Singh, D.P., 1999. Removal of chromium ions by agarimmobilized cells of the cyanobacterium Anacystis nidulans in a continuousflow bioreactor. Enzyme and Microbial Technology 25, 564e568.

Kumar, R., Bhatia, D., Singh, R., Rani, S., Bishnoi, N.R., 2011. Sorption of heavy metalsfrom electroplating effluent using immobilized biomass Trichoderma viride ina continuous packed-bed column. International Biodeterioration and Biodeg-radation 65, 1133e1139.

Kumar, R., Bishnoi, N.R., Garima, Bishnoi, K., 2008. Biosorption of chromium(VI)from aqueous solution and electroplating wastewater using fungal biomass.Chemical Engineering Journal 135, 202e208.

Kuyucak, N., Volesky, B., 1989. Accumulation of cobalt by marine alga. Biotech-nology and Bioengineering 33, 809e814.

Lagergren, S., 1898. Zurtheorie der sogenanntenadsorption geloster stoffe, KungligaSvenska vetenskapaskaademiens. Handlingar 24, 1e39.

Levankumar, L., Muthukumaran, V., Gobinath, M.B., 2009. Batch adsorption andkinetics of chromium(VI) removal from aqueous solutions by Ocimum ameri-canum L. seed pods. Journal of Hazardous Material 161, 709e713.

Montazer-Rahmati, M.M., Rabbani, P., Abdolali, A., Keshtkar, A.R., 2011. Kinetics andequilibrium studies on biosorption of cadmium, lead, and nickel ions fromaqueous solutions by intact and chemically modified brown algae. Journal ofHazardous Materials 185, 401e407.

Mor, S., Ravindera, K., Bishnoi, N.R., 2002. Adsorption of chromium using activatedBaggase carbon as adsorbent. Indian Journal of Environmental Protection 22,564e568.

Ozturk, A., Artan, T., Ayar, A., 2004. Biosorption of nickel (II) and copper (II) ionsfrom aqueous solution by Streptomyces coelicolor A3(2). Colloids and Surfaces B:Biointerfaces 34, 105e111.

Palmieri, M.C., 2001. Estudo da utilização de biomassas para biossorção de terras-raras. PhD thesis, Instituto de Química, Universidade Estadual Paulista, Arara-quara, Brazil.

Saravanane, R., Sundararajan, T., Sivamurthyreddy, S., 2002. Efficiency of chemicallymodified low cost adsorbents for the removal of heavy metals fromwastewater.Indian Journal of Environmental Health 44, 78e81.

Say, R., Denizli, A., Arica, Y.M., 2001. Biosorption of cadmium(II), lead(II) and cop-per(II) with the filamentous fungus Phanerochaete chrysosporium. BioresourceTechnology 76, 67e70.

Sharma, D.C., Forster, C.F., 1995. Continuous adsorption and desorption of chro-mium ions by sphagnum moss peat from acidic solution (pH 2). ProcessBiochemistry 30, 293e298.

Singh, R., Chadetrika, R., Kumar, R., Bishnoi, K., Bhatia, D., Kumar, A., Bishnoi, N.R.,Singh, N., 2010. Biosorption optimization of lead (II), cadmium (II) and copper(II) using response surface methodology and applicability in isotherms andthermodynamics modeling. Journal of Hazardous Material 174, 623e634.

Singh, R., Kumar, A., Kirrolia, A., Kumar, R., Yadav, N., Bishnoi, N.R., Lohchab, R.K.,2011. Removal of sulphate, COD and Cr (VI) in simulated and real wastewater bysulphate reducing bacteria enrichment in small bioreactor and FTIR study.Bioresource Technology 102, 677e682.

Tunali, S., Kiran, I., Akar, T., 2005. Chromium(VI) biosorption characteristics ofNeurospora crasa fungal biomass. Minerals Engineering 18, 681e689.

Vijayaraghavan, K., Yun, Y.S., 2008. Bacterial biosorbents and biosorption. Biotech-nology Advances 26, 266e291.

Volesky, B., 2003. Sorption and biosorption. BV Sorbex, Inc., Montreal-St. Lambert,Quebec, Canada.

Volesky, B., 2007. Biosorption and me. Water Research 41, 4017e4029.Volesky, B., Naja, G., 2005. Biosorption: application strategies. In: IBS-2005, South

Africa, 20.09.2006. http://biosorption.mcgill.ca/publication/index.htm>.Zafar, S., Aqil, F., Ahmad, I., 2007. Metal tolerance and biosorption potential of

filamentous fungi isolated from metal contaminated agricultural soil. Bio-resource Technology 98, 2557e2561.

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