Anukthi C. Poojari, Et Al
Anukthi C. Poojari, Et Al
Anukthi C. Poojari, Et Al
*Corresponding author
ABSTRACT
The effective removal of Cr (VI) from aqueous solutions in a batch system using of
low-cost biosorbent rind of Orange (Citrus sinensis), (L.) Osbeck was studied. The
FTIR study of acid treated biosorbent showed that the possibility of availability of
function groups such as hydroxyl, carbonyl, carboxylic etc. The SEM represents a
porous structure with large surface area. The effects of operational factors
Keywords including solution pH, biosorbent dose, initial Cr (VI) concentration, contact time
and temperature were studied. The optimum solution pH for Cr (VI) biosorption by
Effective biosorbent was 2.0 with the optimal removal 71.01 %. The adsorbent dose 5 mg/ml
removal, was enough for optimal removal of 73.91 %. The equilibrium was achieved after
Chromium (VI), 150 minutes of contact. The equilibrium data were well described by typical
Rind of Orange Langmuir, Freundlich, Dubinin-Kaganer-Redushkevich (DKR) and Temkin
(Citrus sinensis), adsorption isotherms. Sorption equilibrium exhibited better fit to Langmuir
(L.) Osbeck isotherm (R = 0.9986) than Freundlich isotherm (R = 0.9153), Temkin isotherm (R
FTIR, SEM, = 0.8903) and Dubinin-Kaganer-Redushkevich (DKR) isotherm (R = 0.7413). The
Adsorption maximum adsorption capacity determined from Langmuir isotherm was found to
isotherms, be 10.7411 mg per g of biosorbent. Furthermore, to determine the adsorption
Adsorption mechanism, a detailed analysis has been conducted by testing kinetic models such
kinetics, as pseudo-first-order, pseudo-second-order, Elovich equation and Weber & Morris
Thermodynamic intra-particle diffusion rate equation. Results clearly indicates that the pseudo-
study second-order kinetic model was found to be correlate the experimental data
strongest than other three kinetic models. Thermodynamic study revealed that the
biosorption process was spontaneous, endothermic and increasing randomness of
the solid solution interfaces. The rind of Orange (Citrus sinensis), (L.) Osbeck used
successfully for removal of Cr (VI) from aqueous solutions, can be used very
promisingly for industrial wastewater treatment.
653
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
654
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
1989), coconut jute (Chand et al 1994), particle diffusion rate equation) were
coconut tree sawdust (Selvi et al 2001), employed to understand the probable
native and immobilized sugarcane bagasse adsorption mechanism. Thermodynamic
(Ullah et al 2013), synthetic material (Yu et studies were also carried out to estimate the
al 2013), inorganic materials (Rosales- standard free energy change ( G0), standard
Landeros 2013), have been used for Cr (VI) enthalpy change ( H0) and standard entropy
removal. change ( S0).
655
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
The mixture was filtered and the powder placed on a shaker with a constant speed and
residue was washed with distilled water, left to equilibrate. The samples were
several times to remove any acid contents. collected at predefined time intervals,
This filtered biomass was first dried, at room centrifuged, the content was separated from
temperature and then in an oven at 105C for the biosorbents by filtration, using
1-2 hrs. For further use, the dried biomass Whatmann filter paper and amount of Cr
was stored in air tighten plastic bottle to (VI) in the supernatant/filtrate solutions was
protect it from moisture. determined.
656
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
657
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
presence of carboxyl acid groups in the process was maximum with 71.01 % and
biomass. The peak at 1508 cm-1 is associated after increasing pH, adsorption was
with the stretching in aromatic rings. The decreased. According to the solubility
peaks observed at 1074 cm-1 are due to C-H equilibrium of chromium, HCrO4- is the
and C-O bonds. The OH, NH, carbonyl and dominant species of Cr (VI) at a pH 2. As
carboxyl groups are important sorption sites the pH increases, the dominant form of
(Volesky 2003). As compared to simple chromium becomes CrO42- and Cr2O72-.
biosorbent, biosorbent loaded with Cr (VI) Furthermore, the surface of biosorbent may
ions, the broadening of -OH peak at 3421 be positively charged at pH 2. Therefore, at
cm-1 and carbonyl group peak at 1636 cm-1 this pH it is likely to be biosorbed Cr (VI)
was observed. This indicates the onto biosorbent through electrostatic
involvement of hydroxyl and carbonyl attraction and /or by the binding of HCrO4-
groups in the biosorption of Cr (VI). to acidic functional groups on the surface of
biosorbent. Also at pH 2, the number of
Characterization of biosorbent by protons available on the surface of
Scanning Electron Microscope (SEM) biosorbent increases, which increases the
analysis attraction between HCrO4- & biosorbent and
increases the biosorption capacity (Rao et al
The surface characteristics, structure and 1992). As the pH of the solution increases,
particle size distribution of biosorbent charges on the surface of biosorbent
before and after biosorption was examined becomes negative, this leads to generation of
using Scanning Electron Microscope (SEM). repulsive forces between Cr (VI) &
The SEM micrographs are shown in Fig. 2. biosorbent and inhibits biosorption and
(a and b). These micrographs represent a resultantly percent Cr(VI) uptake may
porous structure with large surface area. The decrease.
SEM clearly demonstrated that there is more
uniformity after biosorption on metal ions in Effect of biosorbent dose
comparison to before biosorption. It was
evident from the micrographs that the Effect of biosorbent dose of metal ions
biosorbent presents an unequal structure biosorption onto biosorbent which is an
before metal biosorbed. The number of important parameter was studied while
canals in the biosorbent was higher in the conducting batch adsorption studies. The
initial case. The metal ions adsorbed on the sorption capacity of Cr (VI) on to the rind of
cell wall matrix and created stronger cross Orange (Citrus sinensis), (L.) Osbeck by
linking and uniformity on the surface of varying biosorbent dose from 1.0 mg/ml to
biosorbent. 15.00 mg/ml is as shown in Fig. 4. From the
results it was found that biosorption of Cr
Effect of pH (VI) increases with increase in biosorbent
dosage and is highly dependent on
The biosorption capacity of the adsorbent biosorbent concentration. Increase in
and speciation of metals in the solution is biosorption by increase in biosorbent dose is
pH dependent. The optimization of pH was because of increase of ion exchange site
done by varying the pH in the range of 1-8 ability, surface areas and the number of
for bisorption of Cr(VI) and pH trend available adsorption sites (Naiya et al 2009).
observed in this case is shown in Fig. 3. It The point of saturation for rind of Orange
was found that at pH 2 the biosorption (Citrus sinensis), (L.) Osbeck was found at 5
658
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
mg/ml of biosorbent dose with 73.91 % of increases with increase in contact time until
removal efficiency. The decrease in it reached equilibrium. The optimum contact
efficiency at higher biosorbent concentration time for biosorption of Cr (VI) onto the rind
could be explained as a consequence of of Orange (Citrus sinensis), (L.) Osbeck was
partial aggregation of biosorbent which 150 minutes with maximum biosorption.
results in a decrease in effective surface area The rapid uptake of Cr (VI) is due to the
for metal uptake (Karthikeyan 2007). The availability of ample active sites for
biosorbent dose 5 mg/ml was chosen for all sorption. A further increase in the contact
further studies. time has a negligible effect on the
biosorption capacity of Cr (VI) biosorption.
Effect of initial chromium (VI) So a contact time of 150 minutes was fixed
concentration for further experiments.
Contact time plays an important role in The Langmuir equation, which is valid for
affecting efficiency of biosorption. Contact monolayer sorption onto a surface of finite
time is the time needed for biosorption number of identical sites, is given by;
process to achieve equilibrium when no
more changes in biosorptive concentration (3)
were observed after a certain period of time.
The contact time which is required to
achieve equilibrium depends on the where qm is the maximum biosorption
differences in the characteristics properties capacity of biosorbent (mg g-1). b is the
of the biosorbents. In order to optimize the Langmuir biosorption constant (L mg-1)
contact time for the maximum uptake of Cr related to the affinity between the biosorbent
(VI), contact time was varied between 10 and sorbate.
minutes 180 minutes on the removal of Cr
(VI) from aqueous solutions in the Linearized Langmuir isotherm allows the
concentration of Cr (VI) 10 mg/L, calculation of biosorprtion capacities and
biosorbent dose 5 mg/ml, optimum pH 2.0 Langmuir constants and is represented as;
and 300C temperature (Fig. 6.). The results
obtained from the biosorption capacity of Cr (4)
(VI) onto rind of Orange (Citrus sinensis),
(L.) Osbeck showed that the biosorption
659
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
The linear plots of 1/qe vs 1/ce is shown in concentration of 5 mg/L -250 mg/L of Cr
Fig. 7 (a). The two constants b and qm are (VI).
calculated from the slope (1/qmb) and
intercept (1/qm) of the line. The values of qm, Freundlich adsorption isotherm
b and regression coefficient (R2) are listed in (Freundlich 1906)
Table 1.
Freundlich equation is represented by;
Maximum biosorption capacity of adsorbent
(qm) is found to be 10.7411 mg per g of (7)
biosorbent which is higher than the other
biosorbents used by many authors. where K and n are empirical constants
incorporating all parameters affecting the
The essential characteristics of the biosorption process such as, biosorption
Langmuir isotherm parameters can be used capacity and biosorption intensity
to predict the affinity between the biosorbate respectively.
and biosorbent using separation factor or
dimensionless equilibrium parameters, RL Linearized Freundlich adsorption isotherm
expressed as in the following equation; was used to evaluate the biosorption data
and is represented as,
RL (5)
(8)
where b is the Langmuir constant and Ci is
the maximum initial concentration of Cr Equilibrium data for the biosorption is
(VI). The value of separation parameters RL plotted as log qe vs log Ce, as shown in Fig. 7
provides important information about the (b). The two constants n and K are
nature of biosorption. The value of RL calculated from the slope (1/n) and intercept
indicated the type of Langmuir isotherm to (log K) of the line, respectively. The values
be irreversible (RL = 0), favorable (0 < RL < of K, 1/n and regression coefficient (R2) are
1), linear (RL = 1) or unfavorable (RL > 1). listed in Table 1.
The RL was found to be 0.1503-0.8984 for
concentration of 5 mg/L -250 mg/L of Cr The n value indicates the degree of non-
(VI). They are in the range of 0-1 which linearity between solution concentration and
indicates favorable biosorption (Malkoc and biosorption as followes: if n = 1, then
Nuhoglu 2005). biosorption is linear; if n < 1, then
biosorption is chemical process; if n > 1,
Biosorption can also be interpreted in terms then biosorption is a physical process. A
of surface area coverage against initial metal relatively slight slope and a small value of 1/
ion concentration and separation factor. n indicate that, the biosorption is good over
Langmuir model for surface area of entire range of concentration. The n value in
biosorbent surface has been represented in Freundlich equation was found to be 2.7878.
the following equation: Since n > 1, this indicates the physical
biosorption of Cr (VI) onto rind of Orange
(6) (Citrus sinensis), (L.) Osbeck. The higher
value of K (3.9801) indicates the higher
where is the suface area coverage. The biosorption capacity of the biosorbent.
was found to be 0.1015-0.8496 for
660
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
662
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
5 mg/ml with optimum pH 2.0 was studied. the biosorption of Cr (VI) onto rind of
Experiments were carried out at different Orange (Citrus sinensis), (L.) Osbeck. The
temperatures from 200C-500C. The samples positive values of S0, shows an affinity of
were allowed to attain equilibrium. biosorbent and the increasing randomness at
Biosorption slightly increases from 200C- the solid solution interface during the
500C. The equilibrium constant (Catena and biosorption process.
Bright 1989) at various temperatures and
thermodynamic parameters of biosorption The present investigation revealed that rind
can be evaluated from the following of Orange (Citrus sinensis), (L.) Osbeck
equations: used as inexpensive, excellent biosorbent for
the removal of Cr (VI) from aqueous
(17) solutions. The FTIR study of acid treated
biosorbent showed that the possibility of
(18) availability of function groups such as
(19) hydroxyl, carbonyl, carboxylic etc. The
(20) SEM represents a porous structure with
large surface area. The optimal parameters
where Kc is the equilibrium constant, Ce is such as solution pH, biosorbent dose, initial
the equilibrium concentrationof Cr (VI) in Cr (VI) concentration, contact time and
solution (mg/L) and CAe is the Cr (VI) temperature determined in the experiment
concentration biosorbed on the biosorbent were effective in determining the efficiency
per liter of solution at equilibrium (mg/L). of Cr (VI) onto rind of Orange (Citrus
G0, H0 and S0 are changes in standard, sinensis), (L.) Osbeck. biosorption
Gibbs free energy (kJ/mol), enthalpy equilibrium exhibited better fit to Langmuir
(kJ/mol) and entropy (J/mol K), isotherm than Freundlich isotherm, Dubinin-
respectively. R is the gas constant (8.314 Kaganer-Redushkevich (DKR) isotherm and
J/mol K), T is the temperature (Kelvin). The Temkin isotherm. The maximum chromium
values of H0 and S0 were determined (VI) loading capacity (qe) of rind of Orange
from the slope ( H0/R) and the intercept (Citrus sinensis), (L.) Osbeck. determined
( S0/R) from the plot of ln Kc versus 1/T from Langmuir adsorption isotherm was
(Fig. 9.). The values of equilibrium constant found to be 10.7411 mg g-1. The pseudo-
(Kc), standard Gibbs free energy change second-order kinetic model was found to be
( G0), standard enthalpy change ( H0) and correlate the experimental data strongest
standard entropy change ( S0) calculated in than other three kinetic models. The
this work were presented in Table 3. The thermodynamic study confirmed that
equilibrium constant (Kc) increases with reaction of biosorption of Cr (VI) onto rind
increase in temperature, which may be of Orange (Citrus sinensis), (L.) Osbeck is
attributed to the increase in the pore size and spontaneous, endothermic and increasing
enhanced rate of intraparticle diffusion. The randomness of the solid solution interfaces.
standard Gibbs free energy change ( G0) is From these observations it can be concluded
small and negative and indicates the that rind of Orange (Citrus sinensis), (L.)
spontaneous nature of the biosorption. The Osbeck has considerable biosorption
values of G0 were found to decreases as the capacity, available in abundant, non-
temperature increases, indicating more hazardous agro material can be used as an
driving force and hence resulting in higher effective indigenous material for treatment
biosorption capacity. The positive values of of wastewater stream containing Cr (VI).
H0, indicating the endothermic nature of
663
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
Fig.1 FTIR spectra (a) biosorbent rind of Orange (Citrus sinensis), (L.) Osbeck (b) biosorbent
rind of Orange (Citrus sinensis), (L.) Osbeck loaded with Cr (VI)
(a)
(b)
664
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
Fig.2 Scanning Electron Microscope (SEM) analysis (a) biosorbent rind of Orange (Citrus
sinensis), (L.) Osbeck (b) biosorbent rind of Orange (Citrus sinensis), (L.) Osbeck loaded with
Cr (VI)
(a)
(b)
Fig.3 Effect of pH on Cr (VI) biosorption by rind of Orange (Citrus sinensis), (L.) Osbeck
(biosorbent dose concentration: 5 mg/ml, Cr (VI) concentration: 10 mg/L, contact time: 150
minutes, temperature: 300C)
665
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
Fig.4 Effect of biosorbent dose concentration on Cr (VI) biosorption by rind of Orange (Citrus
sinensis), (L.) Osbeck (pH: 2, Cr (VI) concentration: 10 mg/L, contact time: 150 minute,
temperature: 300C)
Fig.5 Effect of Cr (VI) concentration on Cr (VI) biosorption by rind of Orange (Citrus sinensis),
(L.) Osbeck (pH: 2, biosorbent dose concentration: 5 mg/L, contact time: 150 minutes,
temperature: 300C)
Fig.6 Effect of contact time on Cr (VI) biosorption by rind of Orange (Citrus sinensis), (L.)
Osbeck pH: 2, biosorbent dose concentration: 5 mg/L, initial Cr (VI) concentration: 10 mg/ml,
temperature: 300C)
666
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
Fig.7 Adsorption isotherm models (a) Langmuir, (b) Freundlich (c) DKR and (d) Temkin for
biosorption of Cr (VI) by rind of Orange (Citrus sinensis), (L.) Osbeck (pH: 2.0, biosorbent dose
concentration: 5 mg/ml, contact time: 150 minutes, temperature: 300C)
(a) (b)
(c) (d)
667
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
(a) (b)
(c) (d)
Fig.9 Plot of lnKc against 1/T for determination of thermodynamic parameters for biosorption of
Cr (VI) by rind of Orange (Citrus sinensis), (L.) Osbeck (pH: 2.0, biosorbent dose concentration:
5 mg/ml, Cr (VI) concentration: 10 mg/L, contact time: 150 minute)
668
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
669
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
Biosorption of copper (II) ions from Selomulya S., Meeyoo V. and Amal
aqueous solutions using moss R.,1999. Mechanisms of Cr (VI)
(Semibarbula orientalis (web.) Wijk. & removal from water by various types of
Marg.). Int. J. Environ. Sci., 1 (4) :402- activated carbons. J. Chem. Technol.
414. Biotechnol., 74 :111-122.
Rosales-Landeros, C., barrera-Diaz,C.E., Septhum,C., Rattanaphani,S., Bremner
Bilyeu,B., Guerrero,V.V., and ,J.B.,and Rattanaphani,V.,2007. An
Nunez,F.U.,2013. A review on Cr (VI) adsorption of Al (III) ions onto
adsorption using inorganic materials. chitosan. J. Hazard. Mater., 148:185-
Am. J. Anal. Chem., 4 : 8-16. 191..
Maind,S.D., Rathod S.V.,and Smith,R.G., and Lec,D.H.K.,1972
Bhalerao,S.A.,2013. Batch adsorption Chromium in Metallic Contaminants
studies on removal of Fe(II) ions from and Human Health. Academic Press,
aqueous solutions by corn cobs (Zea New York.
mays Linn.). Int. J. Chem., 2 (1): 136- Sharma,D.C., and Forster,C.F.,1995 Column
148. studies into the adsorption of chromium
Naiya,T.K., Das, S.K., and (VI) using sphagnum moss peat.
Bhattacharya,A.K.,2009. Adsorption of Bioresour. Technol., 52 (3) : 261-267.
Cd (II) & Pb (II) from aqueous solution Sharma ,D.C.,and Forster,C.F.,1994 The
on activated alumina. J. Coll. Inter. Sci., treatment of chromium wastewaters
21 : 434-451. using the sorptive potential of leaf
Panday,K.K., Prasad ,G.,and mould. Bioresour. Technol., 49: 31-40.
Singh,V.N.,1986. Mixed adsorbents for Sivamani, S., and Prince ,V.,2008.
Cu (II) removal from aqueous solutions. Immanuel, Batch adsorption studies for
Environ. Technol. Lett., 50 : 547-554. chromium removal. J. Environ. Sci. &
Periasamy,K., Srinivasan,K., and Eng., 50 (1): 11-16.
Murugan,P.R.,1991. Studies on Selvi,K., Pattabhi,S., and
chromium (VI) removal by ground nut Kadirvelu,K.,2001.Removal of Cr (VI)
husk. Ind. J. Environ. Health, 33: 433- from aqueous solution by adsorption
439. onto activated carbon. Bioresour.
Pino,G.H., Souza de Messquita,L.M.,Torem Technol., 80: 87-89.
M.L.,and Pinto,G.A.,2006. Biosorption Saran,A., Kumar,H., and
of cadmium by green coconut shell Shrivastava,P.,2013. Performance
powder. J. Min. Eng., 19: 380-387. assessment of sawdust as adsorbent for
Patterson,J.W.,1985. Industrial Wastewater Cr (VI) removal from aqueous
Treatment Technology, Butterworth solutions: a kinetic modeling. Middle-
Publication, Stoneham. East J. Sci. Res., 17 (7): 936-940.
Quintelas,C., Fernandes,B., Castro, J., Srinivasan,K., Balasubramanian,N., and
Figueiredo,H., and Ramakrishnan,T.V.,1988. Studies on
Tavares,T.,2008.Biosorption of Cr (VI) chromium removal by rice husk. Ind. J.
by a Bacillus coagulans biofilm Environ. Health, 30 : 376-387.
supported on granular activated carbon Selvi,K., S. Pattabhi and K. Kadirvelu,
(GAC). Chem. Eng. J., 136: 195-203. Removal of Cr (VI) from aqueous
Rao,P.S., Shashikant,R., solution by adsorption onto coconut tree
Munjunatha,G.S.,1992. J. Environ. Sci. sawdust. Bioresour, Technol., 80 : 87-
Health A, 27 : 2227. 89.
670
Int.J.Curr.Microbiol.App.Sci (2015) 4(4): 653-671
Sawalha,M.F.,Peralta-Videa,J.R.,Romero-
Gonzalez.J., and Gardea-Torresdey,J.L.,
2006. Biosorption of Cd(II), Cr(III) and
Cr (VI) by saltbush (Atriplex
canescens) biomass: Thermodynamic
and isotherm studies. J. Coll. Inter. Sci.,
300 : 100-104.
Temkin,M.K., and Pyzhev,V.,1940. Kinetics
of ammonia synthesis on promoted iron
catalysts. Acta Physiochim. Urrs, 12:
217-222.
Thomas,J.M., and Thomas,W.J.,1997
Principle and Practice of heterogeneous
catalysis, weinheim, VCH,
Ullah,I., Nadeem,R., Iqbal,M., and
Manzoor,Q.,2013. Biosorption of
chromium onto native and immobilized
sugarcane bagasse waste biomass.
Ecological Eng., 60: 99-107.
Volesky,B.,2003. Sorption and biosorption.
Montreal-St. Lambert, Quebec, Canada,
BV Sorbex Inc., 316.
W. T. Tan, S. T. Ooi and C. K. Lee.,1993.
Removal of Cr (VI) from solution by
coconut husk and palm presse fibres.
Environ. Technol., 14: 277-282.
Weber,W.J., and Morris,J.C.,1963. Kinetics
of adsorption on carbon solution. J.
Sanit. Eng. Div. Am. Soc. Civ. Engg., 89
: 31-59.
Yu,W., Zhang,L., Wang,H., and
Chai,L.,2013. Adsorption of Cr (VI)
using synthetic poly (m-
phenylenediamine). J. Hazard. Mat.,
260 : 789-795.
671