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J. Water Environ. Nanotechnol., 1(2): 124-134, Autumn 2016
RESEARCH ARTICLE
* Corresponding Author Email: m.tanzi@ilam.ac.ir
Study of the Adsorpon of Amido Black 10B Dye from Aqueous
Soluon Using Polyaniline Nano-adsorbent: Kinec and Isotherm
Studies
Marjan Tanzi*, Mohsen Mansouri, Maryam Heidarzadeh, Kobra Gheibi
Department of Chemical Engineering, Faculty of Engineering, University of Ilam, Ilam, Iran
Received: 2016.08.27 Accepted: 2016.10.15 Published: 2016.11.01
ABSTRACT
In the present study, adsorpve properes of Polyaniline (PAn) were invesgated for Amido Black 10B
dye in aqueous soluon. Dierent variables, including adsorpon me, adsorbent dosage, soluon pH
and inial dye concentraon were changed, and their eects on dye adsorpon onto PAn nano-adsor-
bent were invesgated. The study yielded the result that an increase in pH decreases the adsorpon
eciency of nano-adsorbent. Also, Dye adsorpon capacity increased with increase in the inial dye
concentraon. Opmum adsorpon me and nano-adsorbent dosage were obtained 30 min and 0.1
gr, respecvely. Kinec studies illustrated that the Amido Black 10B dye adsorpon process onto PAn
nano-adsorbent followed the pseudo-second-order model, which indicates that the adsorpon pro-
cess is chemisorpon-controlled. Also, adsorpon equilibrium data were ed to Freundlich isotherm.
The maximum dye adsorpon capacity, predicted by the Langmuir isotherm, was 142.85 mg/g. More-
over, Dubinin-Radushkevich isotherm showed that the adsorpon of dye onto PAn nano-adsorbent is a
chemisorpon process.
KEYWORDS: Amido Black 10B; Isotherm; Kinec; Nano-adsorbent; Polyaniline
How to cite this arcle
Tanzi M, Mansouri M, Heidarzadeh M, Gheibi K, Study of the Adsorpon of Amido Black 10B Dye from Aqueous
Soluon Using Polyaniline Nano-adsorbent: Kinec and Isotherm Studies. J. Water Environ. Nanotechnol.,
2016; 1(2):124-134. DOI: 10.7508/jwent.2016.02.006
ORIGINAL RESEARCH PAPER
INTRODUCTION
Dyes have been widely used for many years
for various applications such as: textile, pigment,
paint and etc. About 1.6 million tons of dyes are
produced per year and 10–15% of this amount
enters the wastewater stream [1,2]. Dyes are organic
compoundscontainingone or more benzene rings.
Such toxic materials cause irreparable damage
to the environment and humans, such as cancer,
mutagenesis, etc. erefore, removal of dyes from
water is essential and necessary [3]. Typically, dye is
removed from water and wastewater using several
methods such as electrochemical treatment [4],
membrane ltration [5], photocatalytic degradation
[6], as well as adsorption [7-9]. Adsorption
technique is an appropriate and economic way to
produce water with high quality. In adsorption
process, elimination of pollutant from wastewater
is conducted via binding it to an organic or
inorganic adsorbent. e binding can be done by
ion exchange, electrostatic, Vander Waals, etc. Dye
adsorption process through adsorbent is dependent
on various conditions such as adsorption time, pH
of solution, particle size of adsorbent, temperature
M. Tanzi et al. / Adsorpon of Amido Black 10B from Aqueous Soluon
J. Water Environ. Nanotechnol., 1(2): 124-134, Autumn 2016 125
and presence of surfactants [10]. Application of
nano-adsorbents in adsorption of contaminants
from wastewater, due to their high specic surface
area, high adsorption and desorption capacity and
high reactivity, has received extensive consideration
in recent years [11-13]. Dierent nano-adsorbents,
including TiO2/chitosan nanocomposite [14],
ower-shaped Zinc oxide nanoparticles (ZON)
[15], copper oxide nanoparticle loaded on activated
carbon (Cu2 O-NP-AC) [16], magnetic oxidized
multiwalled carbon nanotube-k-carrageenan-
Fe3O4 nanocomposite [17], graphene/Fe3O4/
chitosan nanocomposite [18], have been used for
removal of dye from wastewater.
Among the variety of industrial dyes, Amido
Black 10B is a high toxicity dye which applied to
both of natural and synthetics bers namely, wool,
cotton, silk, polyesters, rayon and acrylics. is
diazo dye causes respiratory diseases and irritation
of skin and eye [19]. Generally, a Little research
has been done regarding the elimination of Amido
Black 10B dye from wastewater by adsorption
process. In the study conducted by Garg et al
(2015), zeolite synthesized from y ash was used as
an adsorbent for the uptake of Amido Black 10B
dye. It was found that optimum zeolite dosage and
contact time were 10g/L and 6 hr, respectively. Also,
maximum dye adsorption was obtained at low pH
in the range 2-5 [19]. e results of the research
carried out by Zhang et al (2016) showed that Zr
(IV) surface-immobilized cross-linked chitosan/
bentonite composite are highly ecient in removal
of Amido Black 10B dye from aqueous solution. It
was found that adsorption data tted the Langmuir
isotherm and the maximum adsorption capacity
was reported to be 418.4 mg/g at natural solution
pH (pH=6) and 298K [20].
Polyaniline is one of the most important
conductive polymers which has ion exchange
properties and is capable of removing various
contaminants such as heavy metals, nitrate, organic
materials as well as dyes from water and wastewater.
Various factors, including polymer synthesis
conditions, the presence of surfactant, size of
polymer and size and type of the dopant aect on
ion exchange properties of polyaniline [21-23]. In
the research carried out by Sharma et al (2016),
polyaniline used for the adsorptive removal of
cationic (crystal violet) and anionic (methyl orange)
dyes from aqueous solutions. e adsorption
capacity was obtained up to 245 and 220 mg/g
for crystal violet and methyl orange, respectively.
Furthermore, both dyes followed pseudo second
order kinetic and Langmuir isotherm models [24].
Bhaumik etal (2013) showed that polypyrrole–
polyaniline nanobre is an eective adsorbent for
removal of Congo red dye from aqueous solution.
e maximum adsorption capacity was found to be
222.22mg/g at 25°C [25].
In the present work, the adsorption of Amido
Black 10B dye from water using polyaniline
nano-adsorbent is experimentally studied. e
experiments were conducted to scrutinize the eect
of dierent experimental parameters including
pH of solution, nano-adsorbent dosage, initial
concentration and adsorption time on adsorption
eciency of dye. Furthermore, kinetic and
isotherm studies of Amido Black 10B adsorption
on polyaniline nano-adsorbent were carried out.
EXPERIMENTAL
Materials and Instruments
Aniline monomer, ammonium peroxydisulfate,
sulfuric acid, sodium hydroxide, sodium
carboxymethyl cellulose and Amido Black 10B
pigment were purchased from Merck (Germany).
Aniline monomer was distilled once before
polymerization to remove the impurities. e
following instruments were also utilized in the
process of the study: a magnetic stirrer (model
HMS 8805, Iran), digital scale (model Traveler
TA30), scanning electron microscope (SEM)
(model KYKY-EM3200, China) and Fourier-
transform infrared (FTIR) spectrometer (model
VERTEX 70; Bruker, Germany). Moreover,
UV–visible spectroscopy (UV-VIS ) (model
Perkin Elmer, lambda 25) was used to determine
the concentration of dye in the solution. e
spectroscopy was calibrated using standard Amido
Black 10B solutions (0.25-15 ppm).
Synthesis of Nano-adsorbent
In order to prepare PAn nano-adsorbent, 2.5 g
of ammonium peroxydisulfate as oxidizing agent,
was added to 100 ml of 1M sulfuric acid containing
sodium carboxymethyl cellulose (0.1 g) as a
surfactant. e solution was stirred by a magnetic
stirrer for 30 minutes. Aerwards, 1 ml of aniline
monomer was added drop-wise to the solution. e
solution was ltered aer 5 hr. In order to remove
126
M. Tanzi et al. / Adsorpon of Amido Black 10B from Aqueous Soluon
J. Water Environ. Nanotechnol., 1(2): 124-134, Autumn 2016
oligomers, impurities and acid, the polymer was
washed several times with distilled water. e nal
product was dried for 48 hours in an oven at 45 °C
and converted into a ne powder.
Dye Adsorption Experiments
Dierent parameters including adsorbent dosage,
pH, adsorption time and initial dye concentration
were changed, and their impacts on the eciency
of PAn nano-adsorbent in removing Amido Black
10B dye from solution was investigated. Also,
kinetic and isotherm studies of dye adsorption were
carried out. In all experiments, solution volume and
stirring speed were 50 ml and 500 rpm. Sulfuric acid
and sodium hydroxide were used to change the pH
of solution. A specied amount of nano-adsorbent
was added to the initial solution with certain dye
concentration. e solution was next stirred using
a magnetic stirrer for a certain time. Aerwards, it
was ltered, and the concentration of dye in solution
was determined using a UV-Vis spectrophotometer
at 618 nm maximum wavelength.
Removal eciency of dye was determined using
the following equation:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(1)
Where, Ci (mg/l) and Cf (mg/l) are the initial and
nal dye concentrations, respectively. qt (mg/g) is
dye adsorption capacity at time (t), and qe (mg/g)
is the amount of adsorption at equilibrium, which
were calculated as follows:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(2)
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(3)
Where, Ct is the concentration of dye at time
(t); Ce is the equilibrium concentration of dye; V is
the solution volume (ml) and m is the PAn nano-
adsorbent mass (gr).
RESULTS AND DISCUSSION
Characterization of Nano-adsorbent
e morphology of the synthesized nano-
adsorbent was investigated using scanning electron
microscopy (SEM). Fig. 1 shows the SEM image
of PAn nano-adsorbent. As shown in gure, the
synthesized adsorbent particles feature nano-scaled
size (e average size is about 59 nm), uniform
distribution, and spherical shape. Presence of
surfactant in polymer synthesis environment, lead
to a decrease in particle size. surfactant can either
form a chemical bond with polymer or be physically
adsorbed, consequently preventing the excessive
growth of the polymer chain and accumulated mass
of particles during polymerization. Nano-adsorbent
has high specic surface area and consequently
Fig. 1. Scanning electron microscopy of Polyaniline nano-adsorbent
Fig. 1. Scanning electron microscopy of Polyaniline nano-adsorbent
M. Tanzi et al. / Adsorpon of Amido Black 10B from Aqueous Soluon
J. Water Environ. Nanotechnol., 1(2): 124-134, Autumn 2016 127
high adsorption capacity.
Fig. 2 shows the infrared spectrum of PAn nano-
adsorbent within the range of 450-4000 Cm-1. As
can be seen, the FTIR spectrum of nano-adsorbent
features peaks at wavelength 1572, 1484, 1296, 1117,
801 Cm-1 ascribed to (C=C stretching vibration of
the quinoid ring), (C=C stretching vibration of the
benzenoid ring), (C-N stretching vibration), (C-H
in-plane deformation), and (C-H out-of-plane
deformation), respectively [26].
Eect of pH
e pH of solution is one of the main factors
aecting the adsorption of adsorbate since
adsorbent surface charge and the degree of
ionization of adsorbate are inuenced by pH.
For investigation the eect of PH of solution
on adsorption eciency, the range of pH was
considered to be 2-10. Adsorbent dosage, initial
concentration and volume of dye solution were 0.1
gr, 30mg/l and 50 ml, respectively. e result was
illustrated in Fig. 3. As it is shown in the gure,
adsorption eciency decreases with increase in pH
value of solution. An increase in the pH of solution
leads to an increase in the negative charge density
of the adsorbent surface area. e electrostatic
repulsion between the negatively charged pigment
and negatively charged surface of the adsorbent
reduces dye adsorption. However, decreasing the
pH of solution increases the adsorption eciency
of nano-adsorbent. e reason might lie in the
fact that at low pH, active sites in the structure of
nano-adsorbent can be protonated. As a result,
the positive charge density of adsorbent surface
area increases, and consequently, dye adsorption
eciency increases due to electrostatic attraction.
More dye adsorption happened at pH values
lower than 6. Hence, the optimum pH of Amido
Black 10B dye solution is in the range 2–6.
erefore, the pH of 6 (natural solution pH) was
used for all other experiments.
Eect of Nano-adsorbent Dosage
Adsorbent dosage is one of the eective
parameters in determining dye adsorption
eciency. Gaining higher adsorption eciency
with less adsorbent dosage reduces the adsorption
cost. In order to evaluate the eect of nano-
adsorbent dosage on dye adsorption, dierent
amounts of PAn (0.02-0.2 gr) was added to 50 ml of
30 mg/l dye solution. e eect of nano-adsorbent
dosage on dye adsorption eciency is shown in Fig.
4. As can be seen, an increase in nano-adsorbent
dosage leads to a rise in adsorption eciency. Dye
adsorption eciency per 0.1 g of nano-adsorbent
dosage was measured 95%, and then remains
constant in the range of 0.1-0.2 gr. erefore, the
optimum nano-adsorbent dosage was considered
to be 0.1 g.
Eect of Adsorption Time and Dye Adsorption
Kinetics
Fig. 5 illustrates the eect of adsorption time on
dye adsorption eciency. e eect of adsorption
time on dye adsorption eciency, was done with
the change in time from 1 to 60 min. As can be
seen, increasing the adsorption time from 1 min to
30 min causes the adsorption eciency to increase
and remain constant aerwards. As a result, the
optimum adsorption time of PAn nano-adsorbent
was determined to be 30 min.
e results of the change of adsorption time
were analyzed to obtain information about the
kinetics of adsorption onto PAn nano-adsorbent.
e adsorption kinetics of Amido Black 10B dye
onto PAn nano-adsorbent was investigated using
the three equations: pseudo-rst-order, pseudo-
second-order, andWeber–Morris.
Pseudo-rst-order kinetic model is based on the
assumption that the process of adsorption can be
controlled by weak interaction between adsorbate
and adsorbent surface (physical adsorption).
Linear form of pseudo-rst-order equation [27] is
expressed as follows:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(4)
Fig. 2. Fourier Transform Infrared Spectroscopy of Polyaniline nano-adsorbent
Fig. 2. Fourier Transform Infrared Spectroscopy of Polyaniline
nano-adsorbent
128
M. Tanzi et al. / Adsorpon of Amido Black 10B from Aqueous Soluon
J. Water Environ. Nanotechnol., 1(2): 124-134, Autumn 2016
Where qe (mg/g) and qt (mg/g) are the amount of
dye adsorbed at equilibrium and at time (t); and K1
is the rate constant of pseudo-rst-order equation.
Fig. 6 shows the plot of the pseudo-rst-order
model for dye adsorption on PAn nano-adsorbent.
e correlation coecient and rate constant of the
pseudo-rst-order model were presented in Table 1.
e adsorption kinetic of Amido Black 10B dye
was also investigated using pseudo-second-order
model. is kinetic model assumes that the process
of dye adsorption is chemisorption. is model is
expressed as follows [28]:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(5)
Where, K2 is the rate constant of pseudo-
second-order model. is equation is presented
in four linear forms, i.e. type 1, type 2, type 3, and
type 4 which were shown in Table 1. Moreover,
the plots of pseudo-second-order model for dye
adsorption through PAn nano-adsorbent were
presented in Figs. 7a-7d. As the gures show, the
pseudo-second-order model, type 1 results in a
better correlation coecient in comparison to the
other types of pseudo-second-order model.
In order to determine whether intraparticle
diusion is a rate-controlling step in dye adsorption,
Weber-Morris model was used for the analysis of
the kinetic data. e Weber-Morris model can be
written as follows [29]:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(6)
Where, Kid is rate constant of Weber-Morris
model; and C is a constant that gives an idea about
the thickness of the boundary layer. If the plot qt
versus t0.5 is linear, the process of dye adsorption
is controlled by diusion resistance. When the
plot passes through the origin, it indicates that
intraparticle diusion is the only rate-controlling
step. e slope and intercept of the plot (Fig. 8) can
be used to calculate values for the constants Kid and
C, respectively. e values were presented in Table 1.
Fig. 3. Effect of pH on adsorption efficiency of Amido Black 10B dye onto Polyaniline nano-
adsorbent
84
86
88
90
92
94
96
98
0246810 12
adsorption efficiency (%)
PH
Fig. 3. Eect of pH on adsorption eciency of Amido Black 10B
dye onto Polyaniline nano-adsorbent
Fig. 4. Effect of adsorbent dosage on adsorption efficiency of Amido Black 10B dye onto
Polyaniline nano-adsorbent
60
65
70
75
80
85
90
95
100
00.05 0.1 0.15 0.2 0.25
adsorption efficiency ( %)
Adsorbent dosage (gr)
Fig. 4. Eect of adsorbent dosage on adsorption eciency of
Amido Black 10B dye onto Polyaniline nano-adsorbent
Fig. 5. Effect of adsorption time on adsorption efficiency of Amido Black 10B dye onto
Polyaniline nano-adsorbent
90
91
92
93
94
95
96
010 20 30 40 50 60 70
Adsorption efficiency (%)
adsorption time(min)
Fig. 5. Eect of adsorption time on adsorption eciency of
Amido Black 10B dye onto Polyaniline nano-adsorbent
Fig. 6. Pseudo-first-order plot of Amido Black 10B adsorption onto Polyaniline nano-adsorbent
y = -0.0375x -0.5335
R² = 0.8493
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0246810 12 14 16
log (qe-qt)
t
Fig. 6. Pseudo-rst-order plot of Amido Black 10B adsorption
onto Polyaniline nano-adsorbent
M. Tanzi et al. / Adsorpon of Amido Black 10B from Aqueous Soluon
J. Water Environ. Nanotechnol., 1(2): 124-134, Autumn 2016 129
Fig. 7(a). Pseudo-second-order plot of Amido Black 10B adsorption onto Polyaniline nano-
adsorbent (type 1)
y = 0.0698x + 0.0053
R² = 1
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
010 20 30 40 50 60 70
t/qt
t
Fig. 7(a). Pseudo-second-order plot of Amido Black 10B ad-
sorption onto Polyaniline nano-adsorbent (type 1)
Fig. 7(b). Pseudo-second-order plot of Amido Black 10B adsorption onto Polyaniline nano-
adsorbent (type 2)
y = 0.001x + 0.0704
R² = 0.4639
0.0698
0.07
0.0702
0.0704
0.0706
0.0708
0.071
0.0712
0.0714
0.0716
00.2 0.4 0.6 0.8 11.2
1/qt
1/t
Fig. 7(b). Pseudo-second-order plot of Amido Black 10B ad-
sorption onto Polyaniline nano-adsorbent (type 2)
Fig. 7(c). Pseudo-second-order plot of Amido Black 10B adsorption onto Polyaniline nano-
adsorbent (type 3)
y = -0.0147x + 14.212
R² = 0.4617
13.95
14
14.05
14.1
14.15
14.2
14.25
14.3
14.35
0246810 12 14 16
qt
qt/t
Fig. 7(c). Pseudo-second-order plot of Amido Black 10B ad-
sorption onto Polyaniline nano-adsorbent (type 3)
Fig. 7(d). Pseudo-second-order plot of Amido Black 10B adsorption onto Polyaniline nano-
adsorbent (type 4)
y = -31.355x + 447.55
R² = 0.4617
-2
0
2
4
6
8
10
12
14
16
14 14.05 14.1 14.15 14.2 14.25 14.3 14.35
qt/t
qt
Fig. 7(d). Pseudo-second-order plot of Amido Black 10B ad-
sorption onto Polyaniline nano-adsorbent (type 4)
Fig. 8. Weber-Morris plot of Amido Black 10B adsorption onto Polyaniline nano-adsorbent
y = 0.043x + 14.01
R² = 0.8686
14
14.05
14.1
14.15
14.2
14.25
14.3
14.35
14.4
0123456789
qt
t
0.5
Fig. 8. Weber-Morris plot of Amido Black 10B adsorption onto
Polyaniline nano-adsorbent
Fig. 9. Effect of initial concentration on adsorption capacity of Amido Black 10B dye onto
Polyaniline nano-adsorbent
0
5
10
15
20
25
30
35
40
45
50
020 40 60 80 100 120
q(mg/g)
initial concentr ation (mg/l)
Fig. 9. Eect of initial concentration on adsorption capacity of
Amido Black 10B dye onto Polyaniline nano-adsorbent
e correlation coecient (R2) of the three kinetic
models, i.e. pseudo-rst-order, pseudo-second-
order (type 1), andWeber–Morris equations for dye
adsorption on PAn nano-adsorbent was obtained
as 0.8493, 1, and 0.8686, respectively (Table 1). So,
the experimental data were well described by the
pseudo-second-order kinetic model, which indicates
that the process of Amido Black 10B dye adsorption
onto PAn nano-adsorbent is chemisorption-
controlled. Also, dye adsorption capacity obtained
through pseudo-second-order kinetic model was
very close to its experimental value.
130
M. Tanzi et al. / Adsorpon of Amido Black 10B from Aqueous Soluon
J. Water Environ. Nanotechnol., 1(2): 124-134, Autumn 2016
Table 1 Kinetic constants for Amido Black 10B dye adsorption.
Parameters
Kinetic model
0.8493
() = 14.29
= 0.2927 , = 0.00863
Pseudo-first-order
1
0.4639
0.4617
0.4617
() = 14.29
= 14.32 , = 0.9192
= 14.20 , = 4.9561
= 14.21 , = 4.7866
= 14.27
,
= 2.1969
Pseudo-second-order
Type 1:
=
+
Type 2:
=
+
Type 3: =
Type 4:
= ()
0.8686
=14.01 , = 0.043
Weber-Morris
Table 1. Kinetic constants for Amido Black 10B dye adsorption
Eect of Initial Concentration and Dye Adsorption
Isotherm
In order to investigate the eect of initial
concentration on adsorption capacity, Amido Black
10B dye solutions with the initial concentration
of 30-100 mg/l were prepared. Fig. 9 shows the
plot of the adsorption capacity based on the
initial concentration of dye. As can be seen, the
adsorption capacity of nano-adsorbent increased
with increasing the initial concentration. When the
initial concentration of the solution changed from
30 mg/l to 100 mg/l, the adsorption capacity of
PAn nano-adsorbent increased from 14.29 to 46.55
mg/g.
e relationship between dye concentration
in solution and the amount of dye adsorbed on
the solid phase at equilibrium was described by
isotherm models. In this study, four adsorption
isotherm models namely Langmuir, Freundlich,
Temkin, and Dubinin–Radushkevich were applied
to explain adsorption isotherm of Amido Black
10B dye onto PAn nano-adsorbent.
Langmuir isotherm model assumes adsorption
energy is independent of surface coverage and
adsorption is limited to a monolayer. Langmuir
isotherm model is expressed as follows [30]:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(7)
Here, qm is the maximum adsorption capacity
(mg/g); and KL is adsorption constant of Langmuir
Table 2 Isotherm constants for Amido Black 10B dye adsorption.
Parameters
Isotherm model
0.9579
= 0.79157 , = 0.04794
Freundlich
0.7478
0.9243
0.3731
0.3731
= 102.04 , = 0.1259 , = 0.07358 0.20933
= 142.85 , = 0.0810 , = 0.10989 0.29154
= 66.837 , = 0.2525 , = 0.03809 0.11661
= 127.61
,
= 0.0942
,
= 0.09597 0.26137
Langmuir
Type 1:
=
+
Type 2:
=
+
Type 3: =
Type 4:
=
0.9574
=20.483 , = 0.33786
Temkin
0.8474
= 6 × 10 , =103.87 , = 9.12
Dubinin–Radushkevick
Table 2. Isotherm constants for Amido Black 10B dye adsorption
M. Tanzi et al. / Adsorpon of Amido Black 10B from Aqueous Soluon
J. Water Environ. Nanotechnol., 1(2): 124-134, Autumn 2016 131
isotherm. Langmuir isotherm can be linearized into
four dierent types, as displayed in Table 2. e value
of maximum adsorption capacity and constant of
Langmuir isotherm were calculated from intercept
and slope of Linear Langmuir plots (Figs. 10a-10d).
As the gures show, Linear Langmuir equations, type
2 has a higher correlation coecient in comparison
to the other linear equations. Separation factor (RL)
is a dimensionless constant which expresses the
essential features of the Langmuir isotherm [31]:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(8)
Fig. 10 (a). Langmuir adsorption isotherm of Amido Black 10B onto Polyaniline nano-adsorbent
(type 1 )
y = 0.0098x + 0.0778
R² = 0.7478
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
012345678
Ce/qe
Ce
Fig. 10 (a). Langmuir adsorption isotherm of Amido Black 10B
onto Polyaniline nano-adsorbent (type 1)
Fig. 10 (b). Langmuir adsorption isotherm of Amido Black 10B onto Polyaniline nano-adsorbent
(type 2 )
y = 0.0864x + 0.007
R² = 0.9243
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
1/qe
1/ce
Fig. 10 (b). Langmuir adsorption isotherm of Amido Black 10B
onto Polyaniline nano-adsorbent (type 2)
Fig. 10 (c). Langmuir adsorption isotherm of Amido Black 10B onto Polyaniline nano-adsorbent
(type 3 )
y = -0.0942x + 12.021
R² = 0.3731
0
2
4
6
8
10
12
14
010 20 30 40 50
qe/Ce
qe
Fig. 10 (c). Langmuir adsorption isotherm of Amido Black 10B
onto Polyaniline nano-adsorbent (type 3)
Fig. 10 (d). Langmuir adsorption isotherm of Amido Black 10B onto Polyaniline nano-adsorbent
(type 4 )
y = -3.9593x + 66.837
R² = 0.3731
0
5
10
15
20
25
30
35
40
45
50
45678910 11 12 13
qe
qe/Ce
Fig. 10 (d). Langmuir adsorption isotherm of Amido Black 10B
onto Polyaniline nano-adsorbent (type 4)
Fig. 12. Temkin adsorption isotherm of Amido Black 10B onto Polyaniline nano-adsorbent
y = 20.483x + 6.9204
R² = 0.9574
0
5
10
15
20
25
30
35
40
45
50
00.5 11.5 22.5
qe
ln (Ce)
Fig. 12. Temkin adsorption isotherm of Amido Black 10B onto
Polyaniline nano-adsorbent
Fig. 11. Freundlich adsorption isotherm of Amido Black 10B onto Polyaniline nano-adsorbent
y = 1.2633x -1.3193
R² = 0.9579
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
11.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8
log (qe)
log (Ce)
Fig. 11. Freundlich adsorption isotherm of Amido Black 10B
onto Polyaniline nano-adsorbent
132
M. Tanzi et al. / Adsorpon of Amido Black 10B from Aqueous Soluon
J. Water Environ. Nanotechnol., 1(2): 124-134, Autumn 2016
In this equation, Ci is the initial concentration of
dye; and KL is constant of Langmuir isotherm. Dye
adsorption process onto PAn nano-adsorbent is
favorable when the value of RL obtained in the range
0-1. e separation factors from Linear Langmuir
equation (type 2) obtained in the range of 0.10989-
0.29154.
e Freundlich isotherm is an empirical
model based on the adsorption on heterogeneous
surface. is model does not predict the maximum
adsorption. Also it is suitable for multilayer
adsorption. e Freundlichequation is described as
follows [32]:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(9)
Where, KF and 1/n are Freundlich constant
and adsorption intensity, respectively. Freundlich
equation can be linearized as follows:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(10)
Freundlich constants (KF) and nwere calculated
from theintercept and the slope of the linearized
plots of log(qe) versus log(ce) e plot of Freundlich
model was presented in Fig. 11.
Temkin Isotherm contains a factor that represents
interaction between nano-adsorbent and dye. e
linear form of Temkin isotherm is expressed as
follows [33]:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(11)
Where, KT is equilibrium binding constant of
Temkin isotherm(L/g); bT is constant of Temkin
isotherm; R is the universal gas constant (8.314 J/
mol.K); T is temperature in Kelvin(293.15 K); and
B is constant related to the adsorption heat(J/mol).
Values of B and KT can be obtained via plot of qe
versus ln(Ce) (Fig. 12), which were represented in
Table 2.
Dubinin–Radushkevich isotherm [34] is used
to investigate the type of Amido Black 10B dye
adsorption on PAn nano-adsorbent (physical
or chemical). e linear form of D-R model is
presented in the following equation:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(12)
In these equations, Ce, e, Xm and b are the dye
equilibrium concentration, polanyi potential,
maximum adsorption capacity and constant related
to the adsorption energy, respectively. e value
of b calculated from the slope of Ln(qe) versus ε2
plot (Fig 13). e average adsorption energy, E (kJ/
mol), obtained by b is calculated by the following
equation:
(%)=
×100 (1)
=( )×
(2)
=( )×
(3)
( )=
. (4)
=
(5)
=().+ (6)
=
(7)
=
(8)
=()
(9)
()=()+
() (10)
=ln()+ () , =
(11)
ln () = () =RT ln (1 +
)(12)
=(2). (13)
(13)
If the value of E is between 8 and 16 kJ/mol, the
adsorption process is chemisorption whereas if
E<8 kJ/mol, the adsorption process is of physical
nature. e results of the study indicated that the
process of Amido Black 10B dye adsorption onto
PAn nano-adsorbent is chemisorption.
As shown in Table 2, Freundlich adsorption
isotherm shows the best ttoAmido Black 10B dye
adsorption data on PAn nano-adsorbent because
this model has a higher correlation coecient (R2=
0.9579).
CONCLUSION
PAn nano-adsorbent was prepared through
chemical polymerization and used as an adsorbent
of Amido Black 10B dye from aqueous solution. SEM
and FTIR were used to examine the morphology
and chemical structure of the synthesized nano-
adsorbent. e results of SEM indicated that the
synthesized adsorbent particles feature nano-scaled
size, uniform distribution, and spherical shape.
Such characteristics have been attributed to high
eciency adsorbents. Moreover, FTIR spectrum
has proved the formation of PAn nano-adsorbent.
e adsorption experiments indicated that PAn
nano-adsorbent has high eciency in Amido Black
10B dye adsorption. e research also yielded the
result that optimum adsorption time and adsorbent
dosage of PAn nano-adsorbent was 30 min and 0.1
gr, respectively. Dye adsorption was inuenced
by pH of solution, that is, adsorption eciency
decreases by increasing of pH. Also, dye adsorption
Fig. 13. D-R adsorption isotherm of Amido Black 10B onto Polyaniline nano-adsorbent
y = -6E-09x -2.2646
R² = 0.8474
-4.5
-4
-3.5
-3
-2.5
-2
0100000000 200000000 300000000 400000000
ln (qe)
Ɛ2
Fig. 13. D-R adsorption isotherm of Amido Black 10B onto
Polyaniline nano-adsorbent
M. Tanzi et al. / Adsorpon of Amido Black 10B from Aqueous Soluon
J. Water Environ. Nanotechnol., 1(2): 124-134, Autumn 2016 133
capacity increased with increase in the initial dye
concentration. e kinetic data illustrated that
the adsorption process was controlled by pseudo-
second-order model, which indicates that the
dye adsorption is chemisorption in nature. Also,
the adsorption capacity which calculated by this
model (type 1) was 14.32 mg/g, which is close to
the experimental value (14.29 mg/g). e results
of isotherm studies revealed that the experimental
data were best represented by Freundlich isotherm
model. e correlation coecient of this model
was obtained 0.9579. e maximum adsorption
capacity obtained from Langmuir model, was
142.85 mg/g. e separation factors were in the
range of 0-1, indicating that the adsorption of
Amido Black 10B dye onto PAn nano-adsorbent
was favorable. Moreover, the results obtained
from D-R Isotherm showed that the process of dye
adsorption onto PAn nano-adsorbent was chemical
adsorption. e average adsorption energy was
obtained 9.12 KJ/mol.
CONFLICT OF INTEREST
e authors declare that there are no conicts
of interest regarding the publication of this
manuscript.
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