Available Online http://www.ijncse.com
ISSN Online: 2395-7018
2(5) (2015) 375-391
Isotherm models for the adsorption of Crystal violet dye onto
Zinc chloride activated carbon
V. Nandhakumar[a] *, A.Rajathi [a], K. Ramesh[b] and A. Elavarasan[c]
[a] Department of Chemistry, A.V.V.M Sri Pushpam College, Poondi.
[b] Department of Chemistry, Arasu Engineering College, Kumbakonam.
[c] Department of Chemistry, Sengunthar College of Engineering College, Thiruchengodu.
Corresponding Author: E- mail id: vnchem14@gmail.com
ABSTRACT
An effective adsorbent was prepared from Terminalia catappa Linn fruit shell by Zinc
chloride activation method and its adsorption characteristic was studied for the removal of a
cationic Crystal violet (CV) dye from aqueous solution. pHzpc of the adsorbent was found to be
7.Batch mode adsorption experiments were adopted. Maximum dye removal capacity was
observed at a pH of 9. Equilibrium data were obtained at 303, 313, 323, 333 and 343K for the
initial concentrations of 16, 18, 20, 22 and 24 mg/L. Adsorption isotherm models such as
Langmuir, Freundlich, Temkin and Dubinin – Radus-Kevich isotherms were used to correlate the
equilibrium data. Parameters obtained from the isotherm models were discussed in detail.
Keywords: Crystal violet dye, adsorption, Terminalia catappa fruit shell, activated carbon
pHzpc, Langmuir, Freundlich, Temkin, and Dubinin–Radus-Kevich isotherms.
INTRODUCTION
Various types of synthetic dyestuffs appear in the effluents of industries such as textiles,
printing, plastics, leather and food. The removal of synthetic dyes is of great concern
375
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
because most of them and their degradation products cause serious environmental problems due
to their high stability and complex aromatic structures. Crystal violet (CV) dye belongs to the tri
phenyl methane class and is used largely as histological stain in veterinary medicine, as
bacteriostatic agent and skin disinfectant in the medical community. CV is harmful and can
cause life-threatening injury to the conjunctiva, skin irritation and permanent blindness. Hence it
is necessary to remove the dye from effluent prior to discharge into water sources. There are
several methods used for the treatment of dye containing wastewater. Some of them involve
reverse osmosis, chemical oxidation, photo degradation and adsorption [1]. Among these
methods, adsorption is proved to be superior to other techniques. Adsorption using activated
carbon gave fruitful results for the removal of dyes from wastewater. Preparation of activated
carbon from waste plant bio masses and evaluating its adsorbing potential is the recent trend of
research. Fruit shell of T. catappa is a waste plant bio mass which is chosen as precursor for the
present investigation [2] and the Zinc chloride activation method is adopted as it has the
advantage of producing excellent activated carbons as reported in earlier literatures [3].
MATERIALS AND METHODS
Adsorbate
Crystal violet dye (Molecular formula: C25H30N3Cl, M.W: 407.979, C.I.no. 42555,CAS:
548-62-9, mp: 2050C) of Analar grade purchased from Merck company was used as such without
further purification. Stock solution of 1000 mg/L was prepared by dissolving 1 gm of dye in
1000 mL.
Required initial concentrations of the solution say 16,18,20,22 and 24 mg/L were
prepared from the stock solution by proper dilution [4,5].
Fig. 1 Structure of Crystal violet dye
Maximum wavelength (λmax) of this dye is 590nm
376
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
Preparation of Adsorbents
The Terminalia catappa fruit shell were collected from A.V.V.M Sri pushpam college
campus, Thanjavur Dt., washed with distilled water to remove the surface adhered particles, dried
in sun light for 4 days, chopped into small pieces and powdered in a pulveriser. 50g of the powder
was mixed with 100 ml of 60% ZnCl2 solution. The slurry was kept at room temperature for
24 h to ensure the complete access of the ZnCl2 to the T. catappa shell powder. Excess solution
was decanted and the slurry was heated in muffle furnace at 723K for 3 h. Thus carbonized
samples were washed with 0.5M HCl followed with distilled water until the pH of the washings
attain 7.0. Then it was dried in a hot air oven at 383K for 1 h. The dried material was ground and
sieved to get particle size in between 73 µm and 150 µm. It was designated as T. catappa Zinc
chloride Activated carbon (TCZAC).[6,7].
Fig. 2 Terminalia catappa fruit shell
Batch equilibrium method
Experiments were carried out various temperatures such as 303, 313,323,333 and 343K in
an orbital shaker at a constant speed of 130 rpm using 250 mL conical flasks containing
predetermined dose of TCZAC with 50 mL of dye solution. Samples were agitated for predetermined time and the adsorbent were separated from the solution by centrifugation at 1000 rpm
for 10 min. The absorbance of the centrifugate was estimated to determine the residual dye
concentration. The absorbance of the dye solution was measured at λmax 590 nm using
Systronics Double Beam UV-visible Spectrophotometer: 2202 [8].
The percentage of removal dye was calculated using the following equation
V
q t = (Ci − Ct )
W
(%) of removal = ((Ci-Ct)/Ci) X 100
(1)
377
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
Where;
Ci and Ct are the concentration of adsorbate (mg/L) at initial stage and at time‘t’
respectively
V is the volume of solution (L)
W is the mass of adsorbent (g).
Experimental result obtained from the effect of initial concentration and contact times
were employed in testing the applicability of isotherm and kinetic models.
RESULTS AND DISCUSSION
Determination of Zero Point Charge
In solution, the presence of a net charge on a particle affects the distribution of ions
surrounding it, resulting in an increase in the concentration of counter ions. At pH
zpc,
the
total sum of positive charges and the negative charges on the adsorbent is zero that is the
adsorbent is in neutral charge. When the solution pH is below the pH
zpc
of the adsorbent, surface
of the adsorbent will possess positive charge. On the other hand the surface of the adsorbent will
possess negative charge when the solution pH is above the pH
The pH of the zero point charge (pH
ZPC)
zpc of
the adsorbent.
was determined using pH drift method [9], by
placing 0.2 g of adsorbent in glass stopper bottle containing 50 ml of 0.1M NaCl
solutions. The initial pH of these solutions was adjusted to 2 to 12 by either adding 0.1 M
NaOH or 0.1M HCl [10]. The bottles were placed in an incubator shaker at 298 K for 24 h, and
the final pH of supernatant has been measured. A graph was plotted between final pH and initial
pH of the solution. A straight line was drawn connecting the same pH values of horizontal axis
and vertical axis [11]. The point of intersection of the straight line and the graph was taken as the
pHzpc
of
the
TCZAC
which
was
found
to
be
7
as
shown
in
the
Fig.
3.
378
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
Fig. 3 pHzpc of the carbon
Effect of pH
pH is one of the most important factors controlling the adsorption of dye onto adsorbent
particles, which affects the surface charge of the adsorbents as well as speciation of the solutes
[12]. The hydrogen ion and hydroxyl ions are adsorbed quite strongly and therefore the
adsorption of other ions is affected by the pH of the solution. It is usually expected that increase
of cationic dye adsorption with the increase of pH due to the increase of the negative surface
charge on the adsorbents [13]. The effect of solution pH was studied between initial pH range of
2 to 10, initial pH of the solution was maintained by the addition of 0.1M HCl and 0.1M NaOH
solutions and agitated with 40 mg of adsorbent for 130 min at 303K. The results of effect of
initial
pH
of
dye
solution
on
the
adsorption
of
CV
for
initial
dye
concentration of 16 mg/L is presented in Fig. 4
379
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
Fig. 4 Effect of pH
The lower adsorption at acidic pH is probably due to the presence of excess H+ ions in the
solution which compete with the cationic dye for adsorption sites. As surface positive charge
density decreases with an increase in the solution pH, the electrostatic repulsion between the
positively charged dye and the surface of the adsorbent is lowered, which results in an increase in
the extent of dye adsorption. Higher percentage removal was occurred at pH 9.0 .But still at an
alkaline medium; percentage of removal was not good. This might be due to the interionic
attraction between the OH‒ ions which present in the solution in excess and dye cations. Hence
the remaining experiments were conducted at pH 9 ± 0.5.
Equilibrium studies
Adsorption of dye is considered to be a fast physical/chemical process; it is a collective
term for a number of passive accumulation processes which include ion exchange, co-ordination,
complexation, chelation, Vander Waal’s attraction and micro precipitation. Proper analysis and
design of adsorption separation processes require relevant adsorption equilibria as one of the vital
information.
In equilibrium, certain relationship prevails between solute concentration in solution and
in adsorbed state .Equilibrium concentrations are the function of temperature. Therefore, the
adsorption equilibrium relationship at a given temperature is referred to as adsorption isotherm.
The concentration of dye solution at equilibrium (Ce) and the quantity adsorbed at equilibrium
(qe)
at
different
temperatures
are
collected
in
Table
1.
380
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
Table 1 Equilibrium parameters
[pH: 9, [Ci ]:16,18,20,22 and 24 mg/L, Dose: 40 mg/ 50 mL]
[CV]
(mg/L)
Ce (mg/L)
qe (mg/g)
Temperatures
Temperatures
303
313
323
333
343
303
313
323
333
343
16
1.176
0.980
0.784
0.588
0.392
18.52
18.77
19.01
19.26
19.50
18
2.156
1.764
1.568
1.176
0.784
19.80
20.29
20.53
21.02
21.51
20
2.941
2.549
2.156
1.764
1.176
21.32
21.81
22.30
22.79
23.52
22
3.921
3.529
2.941
2.352
1.764
22.59
23.08
23.82
24.55
25.29
24
4.901
4.313
3.529
3.137
2.549
23.87
24.60
25.58
26.07
26.81
Isotherm studies
The presence of equilibrium between two phases (liquid and solid phase) is rationalized
by adsorption isotherm. The equilibrium data obtained from the experiments were processed
with the following isotherm equations such as Langmuir, Freundlich, Temkin, and DubininRaduskevich. Inference obtained from each isotherm is discussed in detail one by one
Langmuir isotherm
It is a widespread-used model for describing dye sorption onto adsorbent. Langmuir equation
relates to the coverage of molecules on a solid surface and the concentration of contacting
solution at a fixed temperature.
This isotherm is based on the following assumptions such as adsorption limited to monolayer
coverage, all surface sites being a like; one site accommodates one species of the adsorbates and
the ability of a molecule to be adsorbed on a given site independent of its neighboring sites
occupancy. Linear form of Langmuir equation is written in the followingform [14]
C e/q e = 1/qmb + Ce /qm
(2)
Where qe is the amount of solute adsorbed per unit weight of adsorbent (mg/g), C e the
equilibrium concentration of solute in the bulk solution (mg/L), qm is the maximum monolayer
adsorption capacity or saturation capacity (mg/g) and b is the adsorption energy, b is the
reciprocal of the concentration at which half saturation of the adsorbent is reached. The essential
characteristics of Langmuir isotherm can be described by a separation factor, R L, which is
defined
by
the
following
equation
381
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
RL = 1 / (1+ bC0)
(3)
where C0 is the initial concentration of the adsorbate solution. The separation factor
RL indicates the nature of the adsorption process as given below:
RL value
Nature of the process
RL> 1
Unfavourable
RL = 1
Linear
0 < RL< 1
Favourable
RL = 0
Irreversible
The results obtained from Langmuir isotherm model for the adsorption of dye are
presented in Table 2. Concerned isotherm plots are shown in Fig. 5
Table 2 Langmuir isotherm constants for the adsorption of dye
[pH :9, [Ci ]:16,18,20,22 and 24 mg/L, Dose = 40 mg/ 50 mL]
Temperature
qm
b
(K)
(mg/g)
(L/mg)
303
27.0
1.608696
0.995
313
27.0
1.947368
0.995
323
28.5
2.058824
0.990
333
29.4
2.615385
0.994
343
29.4
4.250000
0.997
R2
382
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
The regression coefficient (R2) values are ranged from 0.990 to 0.997 for the five studied
temperatures viz. 303, 313,323,333 and 343 K. These results show the best fitting of the
equilibrium data in the Langmuir isotherms.
The adsorption capacity is the most important characteristic of an adsorbent. It is defined as
the amount of adsorbate taken up by adsorbent per unit mass of adsorbent. This variable is
governed by a series of properties such as pore size and its size distribution, specific surface
area, cation exchange capacity, pH, surface functional groups and also temperature. The mono
layer adsorption capacity qm values (mg/g) for adsorption of CV dye ranged from 27.0270 to
29.4117.
Fig. 5 [pH :9, [Ci ]:16,18,20,22 and 24 mg/L, Dose = 40 mg/ 50 mL]
Further it is noticed that adsorption capacities are slightly increased with the increase of
temperature.
The dimensionless separation factor R L values calculated for various initial concentrations at
different temperatures are given in Table 3 for the adsorption of dye. These values are lie
between 0 and 1 which indicate the favourable adsorption of dye onto TCZAC.
383
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
Table 3: RL values
Temperature 0K
[CV]
mg/L
303
313
323
333
343
16
0.037
0.031
0.029
0.023
0.014
18
0.033
0.027
0.026
0.020
0.012
20
0.031
0.025
0.023
0.018
0.011
22
0.027
0.022
0.021
0.017
0.011
24
0.025
0.020
0.019
0.015
0.009
Freundlich Isotherm
Freundlich isotherm is an empirical equation. It is the most popular model for a single solute
system based on the distribution of solute between the solid phase and aqueous phase at
equilibrium. It suggests that sorption energy exponentially decreases on completion of the
sorptional centers of an adsorbent. The Freundlich model describes the adsorption with in a
restricted range only. It is capable of describing the adsorption of organic and inorganic
compounds on a wide variety of adsorbents [15].
The linear form of the equation has the following form:
ln qe = ln Kf + 1/n lnCe
(4)
where qe is the amount of adsorbate adsorbed (mg/g) at equilibrium, Ce is the equilibrium
concentration of adsorbate in solution (mg/L) and Kf and n are the constants incorporating all
factors affecting the adsorption capacity and intensity of adsorption respectively
As a robust equation, Freundlich isotherm has the ability to fit into nearly all
experimental adsorption–desorption data and is especially excellent for fitting data from
highly heterogeneous sorbent systems. 1/n is the heterogeneity factor and it is a measure of
deviation from linearity of adsorption. A favourable adsorption tends to have n value between1
and 10. The larger value implies a stronger interaction between the adsorbent and adsorbate while
1/n equal to 1 indicates linear adsorption leading to identical adsorption energies for all sites.
Sorption of solute on any sorbent can occur either by physical bonding, ion exchange,
complexation, chelation or through a combination of these interactions. In the first case of
physical bonding, as the solute is loosely bound, it can easily be desorbed using distilled
water. Different mechanisms as mentioned can be involved as the interaction between sorbent and
solute molecules depending upon the functional groups such as hydroxyl, carbonyl and carboxyl
384
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
can present within the structure of adsorbent. The parameter ‘n’ value of Freundlich equation
expresses these phenomena.
The results obtained from Freundlich isotherm model are given in Table 4. The
concerned isotherm plots are shown in Fig. 6.
Table 4 Freundlich isotherm results
[pH :9, [Ci ]:16,18,20,22 and 24 mg/L, Dose = 40 mg/ 50 mL]
kf
Temperature
n
R2
(K)
(mg/g)
303
5.6
18.6
0.980
313
5.6
17.7
0.971
323
5.2
19.5
0.950
333
5.5
20.9
0.978
343
5.7
22.8
0.994
The regression coefficient (R2) for Freundlich isotherms are ranged from 0.950 to 994 for all
the studied temperatures viz. 303, 313, 323,333 and 343 K. It indicates that the experimental data
fit well into Freundlich model.
Freundlich constant adsorption capacity Kf (mg/g) values for adsorption of CV dye ranged
from 17.68 to 22.76 respectively. Further it is noticed that the adsorption capacity increased
with the increase of temperature.
Fig. 6 [pH :9, [Ci ]:16,18,20,22 and 24 mg/L, Dose = 40 mg/ 50 mL]
385
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
The adsorption intensity constant ‘n’ values are ranged from 5.2 to 5.7 for all the studied
temperatures, i.e., between 1 and 10, which indicate the favourable physical adsorption. In
general Freundlich constant values infer a better performance of TCZAC.
Temkin isotherm
The Temkin isotherm assumes that the heat of sorption in the layer would decrease linearly
with coverage due to sorbate-sorbent interactions. Further the fall in the heat of adsorption is not
logarithmic as stated in Freundlich expression [16].
The linear form of Temkin equation is.
qe = RT/bT ln aT + RT/bT ln Ce
(5)
Where, bT is the Temkin constant related to the heat of sorption (J/mg) and aT the
equilibrium binding constant corresponding to the maximum binding energy (L/g). The Temkin
constants aT and bT were calculated from the slopes and intercepts of qe versus ln Ce. The results
obtained from Temkin model for the removal of CV dye are represented in Table 5.
Concerned isotherm plots are shown in Fig. 7. The regression coefficient (R2) values ar e
ranged from 0.931 to 0.990 for the five studied temperatures viz. 303,313, 323, 333 and 343
K. These results show the best fitting of the equilibrium data with Temkin isotherm.
Table 5 Temkin isotherm results
[pH :9, [Ci ]:16,18,20,22 and 24 mg/L, Dose = 40 mg/ 50 mL]
Temperature
bT
aT
R2
(K)
(kJ/mg)
(L/g)
303
6.721
1.238
0.959
313
6.807
1.229
0.968
323
6.357
1.242
0.931
333
6.776
1.215
0.965
343
7.154
1.189
0.990
Equilibrium binding constant ‘aT’ values (L/g) for adsorption of CV dye are ranged from 1.1897
to 1.2425.The Temkin constant related to heat of sorption, b T values (kJ/mg)for adsorption of
CV dye are ranged from 6.3579 to 7.1547. Low values of heat of adsorption, supports he
physisorption mechanism. Both the binding constant ‘aT’ values and heat of sorption, bT
values found to increase with the increase of temperatures.
386
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
Fig. 7 [pH :9, [Ci ]:16,18,20,22 and 24 mg/L, Dose = 40 mg/ 50 mL]
Dubinin – Radus-Kevich isotherm
The Linear form of Dubinin-Radushkevich isotherm is.
ln qe = ln qD - Bε2
(6)
where, qD is the theoretical saturation capacity (mg/g) B is a constant related to the mean
free energy of adsorption per mole of the adsorbate (mol 2/J2) and ε is Polanyi potential which is
related to the equilibrium as given below [17]
ε = RT ln (1+1/Ce)
(7)
The constants qD and B were calculated from the slope and intercept of straight line
obtained from the plot of ln qe versus ε2. The mean free energy of adsorption E calculated
from B using the following equation.
E = 1/ (2B)1/2
(8)
E is a parameter used in predicting the type of adsorption. An E value less than ‘8’ kJ/mol
is an indication of physisorption. Concerned isotherm plots were shown in Fig. 8
387
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
Table 6 Dubinin – Radus-Kevich isotherm results
[pH :9, [Ci ]:16,18,20,22 and 24 mg/L, Dose = 40 mg/ 50 mL]
Temperature
qD
E
(K)
(mg/g)
(kJ/mol)
303
23.6
0.2357
0.819
313
23.6
0.2673
0.835
323
24.3
0.2887
0.774
333
25.0
0.3536
0.823
343
26.0
0.4082
0.883
R2
The regression coefficient (R2) values are ranged from 0.774 to 0.883 for the five studied
temperatures viz. 303, 313,323,333 and 343 K. These values reveal that fitting of equilibrium
data with D-R isotherm are not as good as other isotherms studied earlier.
The mono layer adsorption capacity qD values (mg/g) for adsorption of CV dye are ranged
from 25.0136 and 26.0342 respectively. Further it is noticed that adsorption capacity increased
with an increase in temperature. Values of the mean free energy E(kJ/mol) for the adsorption of
CV dye are ranged from 0.2357 and 0.4082. The very low values of E infer the
physisorption interaction.
Fig. 8 [pH :9, [Ci ]:16,18,20,22 and 24 mg/L, Dose = 40 mg/ 50 mL]
388
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
CONCLUSION
Activated carbon prepared from T. catappa Linn fruit shell by Zinc chloride activation
method (TCZAC) found to have pH
zpc
7.But the maximum adsorption of Crystal Violet dye was
observed at the initial solution pH 9.Equlibrium data were well fitted into Langmuir, Freundlich,
Temkin isotherms having regression coefficient values (R2) around0.9.The regression
coefficient values (R2) for Dubinin – Radus-Kevich isotherm ranged from 0.774 to 0.883 only.
‘RL’ values obtained from Langmuir isotherm and ‘n’ values obtained from Freundlich isotherm
reveal the favourability adsorption of Crystal Violet dye onto TCZAC. Equilibrium binding
constant ‘aT’ values and the heat of sorption, bT values obtained from the Temkin isotherm
supports the physisorption mechanism and endothermic nature of adsorption. The very low mean
free energy values ‘E’ obtained from the Dubinin – Radushkevich isotherm infer the
physisorption interaction. The adsorption capacities obtained from the isotherms show the
feasibility of TCZAC as an effective adsorbent for the removal of Crystal violet dye from
aqueous solution.
REFERENCES
[1] Akinola, LK; Umar, AM, Adsorption of Crystal Violet onto Adsorbents Derived from
Agricultural Wastes: Kinetic and Equilibrium Studies, J. Appl. Sci. Environ. Manage., 2015
19(2), 279- 288
[2] B. Stephen Inbaraj, N.Sulochana, Mercury adsorption on carbon sorbent derived from
fruit
shell
of
Terminalia
cattapa,
J.
Hazard.
Mater.
B,
133
(2006)
283-290
389
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
[3] K.Ramesh, A.Rajappa and V.Nandhakumar, Adsorption of Methylene Blue onto
Microwave Assisted Zinc Chloride Activated carbon prepared from Delonix regia podsisotherm and Thermodynamic Studies.
[4]Theivarasu Chinniagounder, Mylsamy Shanker and Sivakumar Nageswaran , Adsorptive
Removal of Crystal Violet Dye Using Agricultural Waste Cocoa (theobroma cacao) Shell,
Research Journal of Chemical Sciences ,ISSN 2231-606X Vol. 1(7), 38-45, Oct. (2011)
[5] Luyi Zhang, Huayong Zhang, Wei Guo, Yonglan Tian, Removal of malachite green and
crystal violet cationic dyes from aqueous solution using activated sintering process red mud,
Applied Clay Science 93-94 (2014) 85-93
[6] Namasivayam C. and Sangeetha D., Equilibrium and kinetic studies of adsorption of
phosphate onto ZnCl2 activated coir pith carbon, J. Colloid and Interface Science, 280, 359365 (2004)
[7] Makeswari M., Santhi D., Optimization of preparation of activated carbon from Ricinus
communis leaves by microwave-Assisted Zinc Chloride chemical activation: Competitive
adsorption of Ni2+ ions from aqueous solution, Journal of chemistry, 2013, 1-12 (2013)
[8] T.V. Ramakrishna, G. Aravamudan, M. Vijayakumar, Spectrophotometric determination
of mercury (II) as the ternary complex with rhodamine 6g and iodide, Anal. Chim. Acta 84
(1976) 369-375.
[9] M. Nasiruddin Khan and Anila Sarwar, “Determination of points of zero charge of natural
and treated adsorbents” Surface Review and Letters, Vol. 14, No. 3 (2007) 461–469
[10] M. Nasiruddin Khan and Anila Sarwar, Determination of points of Zero charge of
Natural and treated Adsorbents Surface Review and Letters, Vol.14, No.3 (2007) 461-469
[11] Ho Y.s., Porte RJ.F. and Mc kay G., Equilibrium isotherm studies for the sorption of
divalent metal ions onto peat: copper, nickel and lead single component system. Water, Air,
and Soil pollution. 141, 1-33 9 (2002)
[12] Minguang Dai, Mechanism of Adsorption for Dyes on Activated Carbon, J . Colloid
Interface Sci., 198, 6-10 (1998)
390
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India
Nandhakumar et al.,
[13] Do˘gan M., Ozdemir Y. and Alkan M., Adsorption kinetics and mechanism of cationic
methyl violet and methylene blue dyes onto sepiolite, Dyes Pigments, 75, 701–713 (2007)
[14] Yanyan pei, Man Wang, Di Tian, Xuefeng Xu, Liangjie Yuan., Synthesis of core-shell
SiO2@MgO with flower like morphology for removal of crystal violet in water. Journal of
colloid and Interface Science 453 (2015) 194-201.
[15] Xiao-Yi Huang, Jian-Ping Bin, Huai-Tian Bu, Gang-Biao Jiang, Removal of anionic dye
eosin Y from aqueous solution using ethylenediamine modified chitosan, Carbohydrate
Polymers 84(2011) 1350-1356
[16] Basar, C.A., Removal of direct blue-106 dye from aqueous solution using new activated
carbons developed from pomegranate peel: Adsorption equilibrium and kinetics, J. Harzard.
Mater., B135, 232-241 (2006)
[17] Teles de Vasconcelos L.A., Gonzalez Beca, C.G., Adsorption equilibrium between pin
bark and several ions in aqueous solution Cd(II), Cr(III) and Hg(II), Eur.,water pollut.
Control., 3(6), 29-39 (1993)
Received: 1-12-2015
Accepted: 7-12-2015
Note: This paper is a revised version of the paper already
published in the conference proceedings- Editor-in-Chief
391
Int J Nano Corr Sci and Engg 2(5) (2015) 375-391
International Conference on Chemical and Environmental Research (ICCER 2015), 17th December 2015,
PG and Research Department of Chemistry JAMAL MOHAMED COLLEGE (Autonomous), Tiruchirapalli,
Tamilnadu, India