Adsorptive removal of copper and nickel ions from water using chitosan coated PVC beads.
ABSTRACT A new biosorbent was developed by coating chitosan, a naturally and abundantly available biopolymer, on to polyvinyl chloride (PVC) beads. The biosorbent was characterized by FTIR spectra, porosity and surface area analyses. Equilibrium and column flow adsorption characteristics of copper(II) and nickel(II) ions on the biosorbent were studied. The effect of pH, agitation time, concentration of adsorbate and amount of adsorbent on the extent of adsorption was investigated. The experimental data were fitted to Langmuir and Freundlich adsorption isotherms. The data were analyzed on the basis of Lagergren pseudo first order, pseudo-second order and Weber-Morris intraparticle diffusion models. The maximum monolayer adsorption capacity of chitosan coated PVC sorbent as obtained from Langmuir adsorption isotherm was found to be 87.9 mg g(-1) for Cu(II) and 120.5 mg g(-1) for Ni(II) ions, respectively. In addition, breakthrough curves were obtained from column flow experiments. The experimental results demonstrated that chitosan coated PVC beads could be used for the removal of Cu(II) and Ni(II) ions from aqueous medium through adsorption.
- [show abstract] [hide abstract]
ABSTRACT: The adsorption of reactive dye (Reactive Red 189) from aqueous solutions on cross-linked chitosan beads was studied in a batch system. The equilibrium isotherms at different particle sizes (2.3-2.5, 2.5-2.7 and 3.5-3.8mm) and the kinetics of adsorption with respect to the initial dye concentration (4320, 5760 and 7286 g/m(3)), temperature (30, 40 and 50 degrees C), pH (1.0, 3.0, 6.0 and 9.0), and cross-linking ratio (cross-linking agent/chitosan weight ratio: 0.2, 0.5, 0.7 and 1.0) were investigated. Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms and isotherm constants. Equilibrium data fitted very well to the Langmuir model in the entire saturation concentration range (0-1800 g/m(3)). The maximum monolayer adsorption capacities obtained from the Langmuir model are very large, which are 1936, 1686 and 1642 g/kg for small, mediumand large particle sizes, respectively, at pH 3.0, 30 degrees C, and the cross-linking ratio of 0.2. The pseudo first- and second-order kinetic models were used to describe the kinetic data, and the rate constants were evaluated. The experimental data fitted well to the second-order kinetic model, which indicates that the chemical sorption is the rate-limiting step, instead of mass transfer. The initial dye concentration and the solution pH both significantly affect the adsorption capacity, but the temperature and the cross-linking ratio are relatively minor factors. An increase in initial dye concentration results in the increase of adsorption capacity, which also increases with decreasing pH. The activation energy is 43.0 kJ/mol for the adsorption of the dye on the cross-linked chitosan beads at pH 3.0 and initial dye concentration 3768 g/m(3).Journal of Hazardous Materials 08/2002; 93(2):233-48. · 3.93 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Suitability of a novel cross linked, chemically modified chitosan as highly efficient adsorbent for the recovery of toxic chromium(VI) was studied. After cross linking with glutaraldehyde, xanthate group was grafted onto the back bone of chitosan. Sorption was found to be both pH and concentration dependent, with pH 3 being the optimum value. Both, chemically modified beads (CMCB) and flakes (CMCF) followed a pseudo-second-order kinetics with a rate constant of 2.037 and 4.639 g/mg/min, respectively. The equilibrium data followed the Langmuir isotherm model with maximum capacities of 625 mg/g and 256.4 mg/g and for CMCF and CMCB respectively. Desorption studies revealed the reusability of the sorbent for at least 10 cycles without any significant change in adsorption capacities.Bioresource Technology 01/2007; 97(18):2377-82. · 4.75 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: The adsorption of Acid Red 57 (AR57) onto surfactant-modified sepiolite was investigated in aqueous solution in a batch system with respect to contact time, pH and temperature. The surface modification of surfactant-modified sepiolite was controlled using the FTIR technique. The pseudo-first-order, pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data and the rate constants were evaluated. The experimental data fitted very well the pseudo-second-order kinetic model and also followed the intraparticle diffusion model up to 90 min, whereas diffusion is not only the rate controlling step. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were also determined. The Freundlich model agrees with experimental data well. The activation energy, change of free energy, enthalpy and entropy of adsorption were also evaluated for the adsorption of AR57 onto surfactant-modified sepiolite. The results indicate that surfactant-modified sepiolite could be employed as low-cost material for the removal of textile dyes from effluents.Journal of Hazardous Materials 11/2005; 125(1-3):252-9. · 3.93 Impact Factor
Adsorptive removal of copper and nickel ions from water using chitosan coated
Srinivasa R. Popuria,1, Y. Vijayaa, Veera M. Boddub, Krishnaiah Abburia,*
aBiopolymers and Thermophysical Laboratory, Department of Chemistry, Sri Venkateswara University, Tirupati 517 502, Andra Pradesh, India
bUS Army Construction Engineering Research Laboratory, Engineer Research and Development Centre, Champaign, IL 61826, USA
a r t i c l e i n f o
Received 17 September 2007
Received in revised form 25 May 2008
Accepted 27 May 2008
Available online 9 July 2008
a b s t r a c t
A new biosorbent was developed by coating chitosan, a naturally and abundantly available biopolymer,
on to polyvinyl chloride (PVC) beads. The biosorbent was characterized by FTIR spectra, porosity and sur-
face area analyses. Equilibrium and column flow adsorption characteristics of copper(II) and nickel(II)
ions on the biosorbent were studied. The effect of pH, agitation time, concentration of adsorbate and
amount of adsorbent on the extent of adsorption was investigated. The experimental data were fitted
to Langmuir and Freundlich adsorption isotherms. The data were analyzed on the basis of Lagergren
pseudo first order, pseudo-second order and Weber–Morris intraparticle diffusion models. The maximum
monolayer adsorption capacity of chitosan coated PVC sorbent as obtained from Langmuir adsorption iso-
therm was found to be 87.9 mg g?1for Cu(II) and 120.5 mg g?1for Ni(II) ions, respectively. In addition,
breakthrough curves were obtained from column flow experiments. The experimental results demon-
strated that chitosan coated PVC beads could be used for the removal of Cu(II) and Ni(II) ions from aque-
ous medium through adsorption.
? 2008 Elsevier Ltd. All rights reserved.
Techniques such as chemical precipitation, evaporation, electro
deposition, ion exchange, adsorption, and membrane separation
have been used to remove and recover metal ions from wastewa-
ter. However, these technologies are either ineffective or expensive
when heavy metals are present in the wastewater at low concen-
trations. Adsorption is highly effective, inexpensive and easy to
operate among the physicochemical treatment processes. Conse-
quently numerous low cost alternatives have been studied includ-
ing fly ash (Rao et al., 2002), agricultural wastes (Marshall and
Johns, 1996; Wafwoyo et al., 1999), banana pith (Low et al.,
1995), chitin and chitosan (Sankararamakrishnan et al., 2006; Che-
ung et al., 2003; Jeon and Holl, 2004).
Chitosan is a partially deacetylated product of chitin, which has
many useful features such as biocompatibility, biodegradability,
and antibacterial property. The adsorption characteristics of Cu(II)
and Ni(II) from aqueous solutions on chitosan and calcium alginate
biopolymers, and their derivatives were investigated (Huang et al.,
1996). Adsorption behavior of flake and bead types of chitosans
prepared from fishery wastes towards metal and dye was com-
pared (Wu et al., 2000). Several studies were conducted to improve
the properties of chitosan and to enhance its adsorption capacity
and selectivity for trace metal ions. In order to overcome the diffi-
culties associated with its softness and tendency to agglomerate or
form a gel in aqueous solutions, modifications were carried out by
coating chitosan on alumina for the removal of Cr(VI) (Veera et al.,
2003), and on perlite for the removal of Cr(VI) (Sameem et al.,
2003), and Cu(II) and Ni(II) (Kalyani et al., 2005).
The biosorbents prepared from shrimp chitin and crab chitosan
were tested for their removal and recovery efficiency for Cd(II),
Cr(III) and Ni(II) ions (Chui et al., 1996; Tseng et al., 1999). Ni
and Xu (1996) synthesized a series of resins based on chitosan
and investigated adsorption capacity, rate and selectivity for differ-
ent metal ions. Wan Ngah et al. (2004) and Schmuhl et al. (2001)
studied the removal of Cu(II) from aqueous solutions using chito-
san, and chitosan cross-linked with glutaraldehyde, epichlorohy-
drin and ethylene glycol diglycidyl ether. Adsorption removal of
Cu(II) ions from simulated rinse solutions containing several che-
lating agents was studied using chitosan (Juang et al., 1999). The
effect of different organic acids on the capacity of chitosan flakes
to remove heavy metal ions from aqueous solutions was reported
by Bassi et al. (1999). Nickel imprinted chitosan resin (Tianwei et
al., 2001) and cross-linked chitosan with copper as the template
(Zuoying et al., 2001) were prepared to improve the adsorption
capacity and selectivity for trace metal ions.
In this investigation an attempt was made to overcome the
mass transfer limitations by synthesizing a biosorbent by coating
chitosan on the surface of PVC beads. The biosorbent was
0960-8524/$ - see front matter ? 2008 Elsevier Ltd. All rights reserved.
* Corresponding author. Tel.: +91 93939621986.
E-mail address: firstname.lastname@example.org (K. Abburi).
1Department of Biological and Chemical Sciences, The University of West Indies,
Bioresource Technology 100 (2009) 194–199
Contents lists available at ScienceDirect
journal homepage: www.elsevier.com/locate/biortech
characterized by FTIR spectral analysis, porosity and surface area
measurements. The basic objectives of the study include; (1) to
study the adsorption characteristics of Cu(II) and Ni(II) on chitosan
coated PVC beads under equilibrium and column flow conditions,
(2) to understand the kinetics and (3) to model the adsorption pro-
cess. For this purpose, the effect of various factors affecting the
adsorption process, such as time of contact, initial pH of the solu-
tion, adsorbent dose and metal ion concentration were investi-
gated. The experimental data were fitted to Freundlich and
Langmuir adsorption isotherm models. The results were also ana-
lyzed on the basis of Lagergren pseudo-first order, pseudo-second
order kinetic equations and intraparticle diffusion model. Column
adsorption studies were conducted to evaluate the metal adsorp-
tion capacity in a dynamic flow method and to obtain break-
Analytical grade nickel ammonium sulphate and copper sul-
phate were purchased from S.D. Fine Chemicals, for nickel(II) and
copper(II) ion sources. Hydrochloric acid and sodium hydroxide
used for pH adjustment were obtained from Chemical Drug House
Ltd., India. Commercial PVC beads and chitosan were purchased
from Aldrich Chemical Company, USA. Highly pure water is pre-
pared in the laboratory by double distillation of deionised water
in quartz distillation plant (Bhanu Scientific Company, Banglore,
The stock solutions of Cu(II) and Ni(II) were prepared by dis-
solving 3.929 g of copper sulphate and 6.7302 g of nickel ammo-
nium sulphate in 1000 mL of double distilled water such that
each mL of the solution contains 1 mg of divalent metal. The exact
concentration of each metal ion solution was calculated on mass
basis and expressed in terms of mg L?1. The required lower con-
centrations were prepared by dilution of the stock solution. All pre-
cautions were taken to minimize the loss due to evaporation
during the preparation of solutions and subsequent measurements.
The stock solutions were prepared fresh for each experiment as the
concentration of the stock solution may change on long standing.
2.2. Preparation of chitosan coated PVC beads
Medium molecular weight chitosan was sieved to remove dust
and small particles. The sieved chitosan was boiled for 30 min and
rinsed several times with deionized double distilled water to des-
orb any impurities from the chitosan. Then, dried under vacuum
for 3 days and kept in desiccators before use. About 30 g of chito-
san was slowly added to 1 L of 0.2 M oxalic acid solution under
continuous stirring at 40–50 ?C for about 4 h to facilitate the for-
mation of viscous gel. The gel was allowed to stay over night to en-
able the gas bubbles to escape. PVC beads were first stirred with
0.2 M oxalic acid for 6 h at room temperature, filtered and washed
with deionized water. About 60 g of acid treated PVC beads were
slowly added to the diluted chitosan gel and stirred for 12 h at
40–50 ?C. The beads coated with chitosan were then dropped into
a 0.5 M NaOH precipitation bath to neutralize the excess acid. The
beads were separated from NaOH bath, and washed several times
with deionized distilled water to a neutral pH. The beads were
dried in a freeze drier and stored in desiccators.
2.3. FTIR spectral and surface area analysis
Fourier transform Infrared spectra of biosorbent before and
after adsorption of metal ions were recorded in the frequency
range of 400–4000 cm?1using FTIR spectrophotometer (Perkin–El-
mer-283B, USA). The samples were formed into pellets with KBr.
Surface area of the chitosan coated PVC beads were measured by
single point BET (Brunauer, Emmett and Teller) method using ther-
mal conductivity detector (Carlo Erba Soptomatic – 1800) with in
the range of 0.1–2000 m2g?1with the sample size of 2–10 mg.
Pycnomatic ATC (automatic temperature control) is uniquely de-
signed for density measurement of solid and powder samples.
Porosity is defined as the fraction of apparent volume of the adsor-
bent that is attributed to the pores detected (Rouquerol et al.,
1994). Pore volume, density and porosity of the biosorbent sam-
ples were measured using Pycnomatic ATC (Thermo Electronic
Corporation, Italy). The cation exchange capacity (CEC) of the sor-
bent samples was obtained by the ammonium acetate solution
procedure. In this method, 1.0 g biomass sample is dispersed in
20 mL of 1.00 M sodium acetate solution. The resulting suspension
is mixed with 20 mL of 1.00 M ammonium acetate and mechani-
cally stirred at room temperature for 1 h and centrifuged for
5 min to extract the Na+ions. The concentration of Na+ions in
the extracted solution was determined by flame atomic absorption
spectroscopy (FAAS), which represents CEC of sorbent. The surface
charge density (SCD) was evaluated from the relation,
SCD ¼ CEC=SA
where SA referred to the concentration of sodium acetate.
2.4. Equilibrium studies
Metal stock solutions were diluted to required concentrations
for obtaining solutions containing 100–500 mg L?1of Cu(II) or
Ni(II) ions. Batch experimental studies were carried out with
known weight of adsorbent and 100 mL of Cu(II) or Ni(II) solution
of desired concentration at an optimum pH in 125 mL Erlenmeyer
flasks. The flasks were agitated on a mechanical shaker (Ashok Uni-
ted Scientific Company, Chennai, India) at 120 rpm for a known
period of time at room temperature. After attaining equilibrium,
adsorbent was separated by filtration using Whatman filter paper
and the aqueous-phase concentration of metal was determined
with atomic absorption spectrophotometer (Perkin–Elmer 2380).
The equilibrium uptake capacity of the biosorbent for each me-
tal ion was calculated according to mass balance,
where qewas the amount adsorbed per unit mass of adsorbent
(mg g?1), Ciand Cewere, respectively, initial and equilibrium con-
centrations of metal ion (mg L?1), m was the mass of adsorbent
(g) and m was volume of solution in liters. Control experiments were
conducted with metal ion solutions in absence of biosorbent and
found no metal adsorption by the walls of the container. Each
experiment was repeated three times independently and the means
were taken. Standard deviation and analytical errors were calcu-
lated and maximum error was found to be ±5%. Error bars were in-
cluded in the figures. The effect of pH of the medium on metal
removal was studied by performing equilibrium sorption experi-
ments at different pH values. A pH meter (Elico, Model, India) with
combined glass electrode was used for pH measurements. Adjust-
ment of pH was made with 0.1 N hydrochloric acid and 0.1 N so-
dium hydroxide solutions. The effect of pH was studied by
keeping the metal ion concentration, the amount of biosorbent,
contact time, and the temperature constant.
2.5. Column adsorption experiments
Column flow adsorption experiments were conducted in a glass
column of about 2.5 cm internal diameter and 10 cm length. The
column was packed with the adsorbent while shaking the column
S.R. Popuri et al./Bioresource Technology 100 (2009) 194–199
so that maximum amount of adsorbent was packed without gaps.
A constant flow rate (2 mL m?1) was maintained through out the
experiment using peristaltic pump (Model 7518-10). The effluent
solution was collected at different time intervals and the concen-
tration of the metal ion in the effluent solution was monitor by
atomic absorption spectrometry. The solutions were diluted appro-
priately prior to analysis. Break through curves for the adsorption
of Cu(II) and Ni(II) on the biosorbent were obtained by plotting vol-
ume of the solution against the ratio of concentrations of metal
ions in the effluent and in the influent solutions (C/Co).
3. Results and discussion
3.1. Characterization of the biosorbent
The FTIR spectrum of chitosan coated PVC beads before adsorp-
tion indicates the presence of predominant peaks at 3351.7 cm?1
(–OH and –NH stretching), 2987.2 and 2901.4 cm?1(–CH stretch-
ing), 1638.2 cm?1(–NH bending in –NH2), 1393.3 cm?1(–NH
deformation vibration in –NH2), and 1065.5 cm?1
stretching). This reveals that all functional groups such as –NH2,
–OH, originally present in chitosan, are intact even after coating
on PVC and are available for interaction with the metal ions. The
peak at 672 cm?1corresponds stretching of C–Cl bond present in
PVC. The FTIR spectra of sorbent after adsorption indicate a shift
in absorption frequency of amino and hydroxyl groups. This may
be attributed to the deformation of O–H and N–H bands as a result
of interaction between the functional groups and metal ions.
The influence of the surface properties on the extent of adsorp-
tion was evaluated by measuring the surface area (120.24 m2g?1),
porosity (52.78%), pore volume (0.167 cm3g?1), cation exchange
capacity (CEC) (4.16 m eq g?1) and surface charge density (SCD)
(0.034 m eq m?2). Porosity is one of the factors that influence the
activity and physical interaction of solids with liquids and gases.
The biosorbent developed has superior properties with 50% higher
porosity. Similar improvement in the properties of chitosan/poly
(vinyl alcohol) blend foams was reported by Wang et al. (2006).
CEC indicates the improvement of the biomass surface towards
the sorption of cationic species in solution. Further more, the sur-
face charge density (SCD) gives an overall intensity of charges on
the solid matrix surface. Transport studies conducted by Findon
et al. (1993) suggested that copper is chelated with the NH2and
OH groups in the chitosan chain. It was confirmed that the amino
groups of chitosan are the major effective binding sites for metal
ions, forming stable complexes by co-ordination (Chui et al.,
1996). The electrons present on nitrogen in the amino groups can
establish dative bonds with transitional metal ions. Some hydroxyl
groups in these biopolymers may function as donors. Hence depro-
tonated hydroxyl groups involved in the co-ordination with metal
ions (Lerivrey et al., 1986).
3.2. Effect of pH on biosorption of nickel(II) and copper(II) ions
The effect of pH on the adsorption of nickel(II) and copper(II)
ions were studied at different pH values using chitosan coated
PVC beads at constant metal ion concentration (100 mg L?1) and
amount of biosorbent (100 mg). The results indicate that the max-
imum uptake of Cu(II) ions takes place at pH 4.0 while the maxi-
mum uptake of Ni(II) ions occurs at an initial pH of 5.0. The
adsorption capacity of the biosorbent increases with increase in
pH of the medium. Similar trend was observed with the adsorption
of copper from aqueous solution by chitosan (Chu, 2002). The low
level of metal ion uptake by the biosorbent at lower pH values
could be attributed to the increased concentration of hydrogen
(H+) ions which compete along with Cu(II) and Ni(II) ions for bind-
ing sites on the biomass. As the pH is lowered, the overall surface
charge on the beads become positive, which will inhibit the
approach of positively charged metal cations. At pH values above
the isoelectric point, there is a net negative charge on the surface
and the ionic point of ligands such as carboxyl, hydroxyl and amino
groups are free so as to promote interaction with the metal cations
(Quek et al. 1998). This would lead to electrostatic attractions
between positively charged cations such as Cu(II) and Ni(II) and
negatively charged binding sites.
3.3. Effect of agitation time and kinetics of metal sorption
The effect of agitation time on the extent of adsorption of met-
als at different concentrations is shown in Figs. 1 and 2 for Cu(II)
and Ni(II), respectively. The extent of adsorption increases with
time and attained equilibrium for all the concentrations of copper
and nickel studied (100, 250 and 500 mg/L) at 210 and 240 m,
respectively. After this equilibrium period, the amount of metal ad-
sorbed did not change significantly with time. The amount of metal
adsorbed versus time curves are smooth and continuous.
In order to investigate the mechanism of sorption, the rate con-
stants of sorption process were determined by using Legergren
first order and a pseudo-second order kinetic models. The values
of the first and second order rate constants are included in Table
1. In many cases the first order equation of Legergren does not fit
well to the whole range of contact time and is generally applicable
over the initial stage of the adsorption processes (McKay and Ho,
1999). The second order kinetic model assumes that the rate limit-
ing step may be chemical adsorption (Chiou and Li, 2002). In many
cases, the adsorption data could be well correlated by second order
rate equation over the entire period of contact time (Sag and Aytay,
2002). The results of the present study indicate that the adsorption
of Cu(II) and Ni(II) on chitosan coated PVC beads follows second or-
der kinetic model .
The results were also analyzed in terms intraparticle diffusion
model to investigate whether the intraparticle diffusion is the rate
controlling step in adsorption of Cu(II) and Ni(II) on chitosan
coated PVC beads. The model proposed by Weber and Morris
(1963) can be written as, qt= Kidt1/2, where Kid(mg g?1min?1/2)
is the rate constant of intraparticle diffusion. The Weber–Morris
plots for adsorption of Ni(II) and Cu(II) are given in Fig. 3. If the
intraparticle diffusion is the sole rate determining step, the plots
of qtvs. t1/2should be linear and pass through the origin (Ozcan
and Ozcan, 2005). The plots in the figure are multi linear with three
distinct regions indicating three different kinetic mechanisms. The
initial curved region corresponds to the external surface uptake,
the second stage relates the gradual uptake reflecting intraparticle
0 100 200300
Adsorption capasity (mg/g)
Fig. 1. Effect of time on biosorption of copper(II) on chitosan coated PVC beads.
S.R. Popuri et al./Bioresource Technology 100 (2009) 194–199
diffusion as the rate liming step and final plateau region indicates
equilibrium uptake. Based on the results it may be concluded that
intra particle diffusion is not only the rate determining factor.
3.4. Effect of adsorbent dose
One of the parameters that strongly affect the biosorption
capacity is the amount of the biosorbent. The dependence of Cu(II)
and Ni(II) sorption on chitosan coated PVC was studied by varying
the amount of the adsorbent from 0.05 g to 0.5 g while keeping the
other parameters such as pH, metal solution volume (100 mL), con-
centration (100 mg/L), and contact time (240 min) constant. In
both cases the removal percentage increases with increasing
adsorbent dose (Fig. 4) from 64% to 94% and 68% to 96% in case
of Cu(II) and Ni(II), respectively. However, the uptake capacity of
metal ion per unit mass of biosorbent (mg g?1) decreases with in-
crease in dose of adsorbent, which may be due to lower utilization
of adsorption capacity of the sorbent at higher dosage.
3.5. Equilibrium modeling
Analysis of the equilibrium data is important to develop an
equation which accurately represents the adsorption process and
which could be used for design purposes. Langmuir and Freundlich
adsorption isotherms were used to fit the experimental data. To
obtained the isotherms, initial concentration of Cu(II) and Ni(II)
were varied from 100 to 500 mg/L while keeping the weight of
chitosan coated PVC beads, pH and contact time constant. The
Langmuir isotherm assumes monolayer adsorption where as the
Freundlich isotherm is an empirical model that is based on sorp-
tion on heterogeneous surface. The parameters of Langmuir and
Freundlich adsorption isotherms, evaluated from the linear plots,
are presented in Table 2 along with the correlation coefficient. Both
the models are capable of representing the data adequately. The
magnitude of the Freundlich constants, KFand n indicate that the
uptake of Cu(II) and Ni(II) from aqueous solutions by the chitosan
coated PVC is feasible. Langmuir constant, Qo, represents the max-
imum monolayer adsorption capacity of the biosorbent. The values
are 87.9 mg g?1and 120.5 mg g?1for Cu(II) and Ni(II), respectively.
Adsorption capacities of chitosan and modified chitosan sorbents,
collected form the literature, are included in Table 3 along with
the values corresponding to chitosan coated PVC for comparison.
The sorbent developed in the present study exhibits higher adsorp-
0 50100150200 250300
Adsorption capasity (mg/g)
Fig. 2. Effect of time on biosorption of nickel(II) on chitosan coated PVC beads.
First order (k1) and second order (k2) rate constants for adsorption of Cu(II) and Ni(II) on chitosan coated PVC
Concentration of metal ion (mg L?1) Cu(II) Ni(II)
1.98 ? 10?4
0.84 ? 10?4
0.43 ? 10?4
2.12 ? 10?4
1.21 ? 10?4
0.73 ? 10?4
0 1015 20
100 mg/g Cu(II)
250 mg/g Cu(II)
500 mg/g Cu(II)
100 mg/g Ni(II)
250 mg/g Ni(II)
500 mg/g Ni(II)
Fig. 3. Weber–Morris plots for adsorption of Cu(II) and Ni(II) on chitosan coated
0 0.10.2 0.30.4 0.50.6
Amount of adsorbent (g)
Fig. 4. Effect of amount of chitosan coated PVC beads on percent removal of
copper(II) and nickel(II) ions.
S.R. Popuri et al./Bioresource Technology 100 (2009) 194–199
tion capacity compared to chitosan in its natural form and most of
the modified forms.
3.6. Column studies
The way in which an experiment is carried out is another
parameter that can affect the capacity of a particular type of adsor-
bent to sequester metals. Since in batch experiments the concen-
tration of adsorbate and the solution pH vary with time, the
same parameters undergo a change along with the length of the
column in continuous flow experiments. The flow rate in packed
column is 2 mL m?1and the residence time of metal ions through
the column is 5.3 min. The concentration profiles of the solution
coming out of the column show that metal removal is fast and
highly effective during the initial phase. Subsequently metal re-
moval decreases, as a consequence of the progressive saturation
of the binding sites. After passing about 300 mL of solution of me-
tal ion solution through the column, the column gets saturated.
The adsorption capacity of the biomass in each column is obtained
by dividing the concentration of metal adsorbed by the total
amount of biomass used. From these studies it can be concluded
that chitosan coated PVC beads is a good biosorbent for removal
of copper and nickel from aqueous medium.
In this study, chitosan coated PVC beads were developed and
used as a biosorbent for the removal of copper(II) and nickel(II)
ions from aqueous solution. The biosorbent is characterized on
the basis of FTIR spectral study and analysis of surface morphology.
The Langmuir adsorption model and Freundlich equation are used
for the mathematical description of the biosorption of Cu(II) and
Ni(II) ions onto chitosan coated PVC beads. The maximum adsorp-
tion capacities of chitosan coated PVC beads used in this study are
87.9 mg g?1for copper and 120.5 mg g?1for nickel. Batch equilib-
rium results suggest that the adsorption process follows second or-
der kinetic model in both the cases. Column experiments show
that it is possible to remove the metal ions from aqueous medium
through biosorption on to chitosan coated PVC beads.
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