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Evaluation of Removal Efficiency of Cu (II) from Aqueous Solution by Natural Leaves

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Activated carbon was prepared from Behda (BEAC), Anjan (AAC), Chinch (CAC), and Bakam Neem (BNAC) leaves. The effects of various parameters such as initial metal concentration, particle size, pH and contact time for the adsorption of Cu (II) on BEAC, AAC, CAC and BNAC were investigated. The amount of adsorbent increased the percentage of metal removal increased accordingly. The optimum pH for the Cu (II) absorption was 7.0 except BEAC. The equilibrium data fit well with both Langmuir and Freundlich models of adsorption. The value of separation factor RL was found to be 0.042, 0.006, 0.048 and 0.308 for BEAC, AAC, CAC and BNAC respectively suggesting the isotherm to be favourable at the concentration studied. The percentage removal of copper ion on to BEAC, AAC, CAC and BNAC were very significant.
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Patil et al. Int. J. Res. Chem. Environ. Vol. 4 Issue 4 (109-114) October 2014
109
ISSN 2248-9649
International Journal of
Research in Chemistry and Environment
Available online at: www.ijrce.org
Research Paper
Evaluation of Removal Efficiency of Cu (II) from Aqueous Solution by
Natural Leaves
Bagwan M., Mustaqeem M. Sharif.1 and *Patil P. R.2
1Department of Chemistry, IES’ H. J. Thim College of Arts and Science, Jalgaon.-425 001, (MS), INDIA
2School of Environmental and Earth Sciences, North Maharashtra University, Jalgaon-425 001, (MS), INDIA
(Received 31st October 2014, Accepted 02nd July 2014)
Abstract: Activated carbon was prepared from Behda (BEAC), Anjan (AAC), Chinch (CAC), and Bakam Neem
(BNAC) leaves. The effects of various parameters such as initial metal concentration, particle size, pH and contact
time for the adsorption of Cu (II) on BEAC, AAC, CAC and BNAC were investigated. The amount of adsorbent
increased the percentage of metal removal increased accordingly. The optimum pH for the Cu (II) absorption was
7.0 except BEAC. The equilibrium data fit well with both Langmuir and Freundlich models of adsorption. The
value of separation factor RL was found to be 0.042, 0.006, 0.048 and 0.308 for BEAC, AAC, CAC and BNAC
respectively suggesting the isotherm to be favourable at the concentration studied. The percentage removal of
copper ion on to BEAC, AAC, CAC and BNAC were very significant.
Keywords: Behda, Anjan, Chinch, Bakam Neem, activated carbon, adsorption, isotherms. © 2014 IJRCE. All rights reserved
Introduction
Pollution from heavy metals is a major concern
in developing countries[1]. Heavy metals are unique
among pollutant and they can accumulate in living tissues
causing disease and disorder[2]. The most common and
harmful heavy metals are aluminium, lead, copper,
nickel, chromium and zinc[3]. They are stable elements
that cannot be metabolized by the body and get passed up
in the food chain to human beings[4]. These toxic heavy-
metal ions are severely contaminating our drinking water
and threatening our health[5]. Copper(II) is known to be
one of the heavy metals and widely used in many
industries including metal cleaning and plating, paper
board, printed circuit board, wood pulp, fertilizer, paints
and pigments, etc.[1] When human consume food and
water with copper concentration exceeding the
permissible limit then they may suffer from nausea,
gastrointestinal disturbance, vomiting, liver or kidney
damage[6]. Therefore there is a growing need for the
development of new, innovative and cost effective
methods and the removal of metals [7].
Adsorption process is considered better as
compared to other methods[8], because of convenience,
easy operation and simplicity of design[9]. In recent years,
considerable attention has been focused on the removal of
copper from aqueous solution using adsorbents derived
from low-cost materials. Several adsorbents, such as dyed
coconut pollen[10], Sennauniflorora leaves[11], Henna
leaves[12], Teak leaves[13], Coconut bagasse[14], Mango
leaf[15], Sugar beet pulp[16], Sugar cane bagasse[17],
Synthetic Geothite[18], polyaniline coated saw dust[19],
Hebba clay[20], Waste tire rubber ash[21], Decanter
cake[22], Chestnut shell[23] and Cement kiln dust[24].
Accordingly, this investigation aims to establish as
elective, rapid and simple procedure for the removal of
Cu (II) from aqueous solutions using powdered activated
carbon, obtained from Behda, Anjan, Chinch, Bakam
Neem leaves from synthetic wastewater and to offer this
adsorbent as local replacement for existing commercial
adsorbent materials.
Material and Methods
Materials: The leaves of Behda, Anjan, Chinch and
Bakam Neem were collected from local field of Jalgaon
District. These waste materials were washed with water,
dried in sunlight, then 600C for 24 h in hot air oven.
Finally, the dried leaves were ground in clean electric
mixer and stored in a clean plastic bag.
Preparation of activated carbon: Dried leaves powder
is treated with conc. H2SO4 at a weight of ratio 1:1. The
resulting black product was kept in an oven maintained at
5000C for 12 h followed by washing with NaHCO3 and
Patil et al. Int. J. Res. Chem. Environ. Vol. 4 Issue 4 (109-114) October 2014
110
water until free from excess acid, the pH of washing
becomes 7.0 and dried at 150 +50C. The resulting
products were grounded and sieved into different particle
sizes range A) 500-850 micron B) 180-500 micron C) 45-
180 micron and stored in a tight lid container for further
studies. The physical properties were analysed by usual
standard methodologies.
Adsorbate: The stock solution of Cu (II) ion was
prepared by dissolving 0.3929 gm of CuSO4.5H2O in
1000 ml with double distilled water. The required
concentration of aqueous solution was prepared from the
stock solution. The pH of the aqueous solution was
adjusted by using 0.1 M HCl or 0.1 M NaOH. Batch
adsorption studies were performed at room temperature.
Experimental methods: The adsorption experiments
were carried out by agitating the carbon with 50, 75, 100
mg L-1 metal ion solution of desired concentration at pH
7.0 and at room temperature (280C) in a mechanical
Shaker (120 rpm) after a defined time interval. Sample
was withdrawn from the shaker at the predetermined time
interval, filtered and the residual concentration of the Cu
(II) metal ion was measured using an Atomic Absorption
Spectrometer (Thermo scientific S-series AA
Spectrometer) at 324.8 nm.
Results and Discussion
Table 1 shows selected adsorbents from natural waste and
Table 2 shows characteristics of the adsorbent.
Effect of contact time: Figure 1 showed the percentage
removal of the Cu (II) metal ions by the BEAC, AAC,
CAC and BNAC as adsorbent. The effect of contact time
was studied in the range of 15, 30, 45, 60, 75, 90, and 120
min was noticed that the Cu (II) metal ion present in the
synthetic wastewater, there was a progression in the
percentage removal of metal ion present in the synthetic
wastewater with time on all selected adsorbents. The
results also showed that, the adsorption was fast at initial
stage of contact period and after that near the equilibrium
it became slower. With the lapse of time, the surface
adsorption sites were exhausted. The remaining vacant
sites were difficult to be occupied by the cation due to
repulsive forces between adsorbate present in solid and
bulk phases.16Adsorptions reach equilibrium within 120
min for all selected adsorbents. From the result of the
adsorption experiment Cu2+ ions had the highest percent
removal of 96.6 at the end of 120 min by the BEAC,
followed by AAC, CAC and BNAC with 99.4, 99.1 and
98.4, respectively.
Effect of particle size: Exposure of adsorbent sites for
solid metal ion interaction is high if the surface area of
adsorbent is high. Hence to study this parameter batch
adsorption studies were done by using three different
particle sizes of BEAC, AAC, CAC and BNAC such as
A= 500-850, B= 180-500, C= 45-180 micron. The
relationship between the size of the particles of the
adsorbent and the copper metal ion removal percentage is
illustrated in Figure 2.
Table 1
Selected adsorbents from natural waste
S. No.
Adsorbent Name
Botanical name
Abbreviation
1
Behda
Terminalliabellerica
BEAC
2
Anjan
Hardwickiabinata
AAC
3
Chinch
Tarmirindus indica
CAC
4
Bakam Neem
Meliaazedarach
BNAC
Table 2
Characteristics of adsorbents
Properties
BEAC
AAC
CAC
BNAC
Density (g cm-3)
0.2961
0.3559
0.2550
0.3781
pH
6.5
6.5
7.0
6.3
Moisture content (%)
16.00
42.40
25.60
11.73
Ash Content (%)
7.60
7.27
10.40
16.03
Figure 1: Effect of contact time on the removal of Cu (II) by the BEAC, AAC, CAC and BNAC: Copper
concentration 50 mg L-1, pH 7, adsorbent dose 4 g L-1, particle size 45-180 micron.
Patil et al. Int. J. Res. Chem. Environ. Vol. 4 Issue 4 (109-114) October 2014
111
Figure 2: Effect of particle size on the adsorption of
Cu (II): Copper concentration: 50 mg L-1, contact
time: 120 min, pH: 7.0, adsorbent dosage4 g L-1,
Particle size: A= 500 -850, B= 180-500, C= 45-180
micron Figure 2 indicates that the percentage Cu (II) ion
removal has increased with the decrease in particle size.
As the particle size is smaller, the surface area per unit
weight of adsorbent is larger and consequently the higher
percentage of metal removal is noted11. The maximum
percentage of Cu (II) ions were removed by taking the
adsorbent size of 45-180 micron. Hence for the entire
study, BEAC, AAC, CAC and BNAC of 45-180 micron
were used in order to produce effective adsorption
process.
Figure 3: Effect of pH on copper adsorption by
BEAC, AAC, CAC and BNAC leaves: Initial
concentration of 50 mg L -1, time 120 min, adsorbent
dose4 g L-1
Effect of pH: In this study the role of hydrogen ion
concentration was examined at different pH. The effect of
initial pH on the extent of removal of Cu (II) ions by
adsorption on BEAC, AAC, CAC and BNAC at 28°C is
given in Figure 3. The adsorptions of Cu (II) ions on the
adsorbents are found to be highly pH dependent. As pH
increases, the extent of removal increases, reaches a
maximum value and then decreases further increased
upto optimum pH. In general, cation binding increases as
pH increases.12.The neutral pH is found to be favourable
in all selected adsorbents. The pH value slightly
decreases and change in pH in the order of 0.1-0.6 units.
This suggests that during the adsorption of copper
species, protons are released from the surface functional
groups like phenolic, carboxylic and enolic groups
present on the carbons. Above pH 7.6, the Cu2+ ions are
also precipitated as copper hydroxide.
Effect of Initial Concentration of Cu (II): In batch
adsorption processes, the initial metal ion concentration
of metal ions in the solution plays a key role as a driving
force to overcome the mass transfer resistance between
the solution and solid phase. The effect of initial metal
ion concentration ranging from 50-100 mg L-1on BEAC,
AAC, CAC and BNAC was studied by taking different
concentrations of Cu (II) solutions at pH 7, while keeping
the dosage of the adsorbent 4 g L-1 constant and
temperature at 280C. The corresponding results obtained
are listed in Table 3 from which it is clear that the percent
adsorption decreases with the increase of initial metal ion
concentration. As a result of the above observations, it is
indicated that the adsorption process of Cu (II) ions on
BEAC, AAC, CAC and BNAC has to be dependent on
concentration of the metal ion solution up to some extent.
Adsorption Isotherms: The adsorption data was
analysed with the help of the Freundlich and Langmuir
isotherms:
The Langmuir isotherm is represented by the following
equation
(Ce/qe) = (1/ b Q0) + (Ce/Q0) (1)
Where,
qe = amount of dye adsorbed at equilibrium (mg g-1),
Ce = equilibrium concentration of dye (mg L-1),
Q0 = Langmuir constant related to adsorption efficiency
(mg g-1) and
b = Langmuir constant related to energy of adsorption (L
mg-1).4
The linear plots of Ce/qe versus Ce suggest the
applicability of the Langmuir isotherms (Figure 4 a, b, c,
d) for BEAC, AAC, CAC and BNAC respectively. The
values of absorption capacity (Q0) and energy absorption
b of BEAC, AAC, CAC and BNAC adsorbents were
determined from the slope and intercept (Table 4). The
high value of correlation coefficient r2 indicates that the
adsorption of Cu (II) ion by BEAC, AAC, CAC and
BNAC follows Langmuir isotherm model.
Table 3: Effect of initial metal concentration on the adsorption of Cu (II) ions by BEAC, AAC, CAC and BNAC:
time = 120 min, pH 7.0, adsorbent dosage = 4 g L -1, V =100 ml, W= 400 mg
Ci
Ce
Qe
% age of Copper removed
BEAC
AAC
CAC
BNAC
BEAC
AAC
CAC
BNAC
BEAC
AAC
CAC
BNAC
50
1.685
0.296
0.445
0.819
12.079
12.426
12.389
12.295
96.629
99.408
99.110
98.361
75
1.801
0.596
0.742
1.306
18.3
18.601
18.565
18.424
97.599
99.205
99.011
98.259
100
1.920
3.208
1.093
2.854
24.52
24.198
24.727
24.287
98.080
96.792
98.908
97.146
Patil et al. Int. J. Res. Chem. Environ. Vol. 4 Issue 4 (109-114) October 2014
112
(a)
(b)
(c)
(d)
Figure 4: Langmuir isotherm for the removal of Cu by adsorption on (a) BEAC. (b) AAC. (c) CAC (d) BNAC
Table 4: Langmuir and Freunlich parameters of adsorption isotherms
adsorbents
Langmuir isotherm results
Freundlich isotherm results
Qo
b
r2
RL
Kf
1/n
r2
BEAC
38.314
0.045
0.958
0.042202
0.144
5.44
0.991
AAC
27.027
3.364
0.999
0.005911
1.270
0.257
0.879
CAC
83.333
0.400
0.998
0.04761
1.365
0.77
0.999
BNAC
38.461
0.634
0.975
0.3075
1.161
0.525
0.937
(a)
(b)
(c)
(d)
Figure 5: Freundlich isotherm for the removal of Cu by adsorption on (a) BEAC, (b) AAC (c) CAC (d) BNAC
Patil et al. Int. J. Res. Chem. Environ. Vol. 4 Issue 4 (109-114) October 2014
113
To confirm favourability of the adsorption
process, the separation factor (RL) is calculated and
presented in Table 4. The values are found to be between
0 and 1 and confirmed that the ongoing adsorption
process is favourable.
RL = 1/ (1+ b Ci) (2)
Here, b is the Langmuir constant and Ci is the initial
concentration of Cu (II).
The Freundlich isotherm is also employed for
the adsorption of Cu (II) on the adsorbent. The
Freundlich isotherm is represented by the following
equation
log qe = log kf + (1/n) log ce (3)
Here, qe is the amount of Cu (II) adsorbed (mg
L-1), ce is the equilibrium concentration of Cu (II) in the
solution (mg L-1) and kf and n are constant incorporating
all factors affecting the adsorption capacity and intensity
of adsorption, respectively. The plot of log qe versus log
ce (Figure 5 a, b, c and d) suggest that applicability of
Freundlich isotherm for BEAC, AAC, CAC and BNAC.
The values of Kf and 1/n were determined from the slope
and intercept of the plots (Table 4). The magnitude of the
exponent n gives an indication of the favourability and kf
the capacity of the adsorbent/adsorbate system. The n
value was 0.1838, 0.7782, 1.2987 and 1.9047 was in
between 1 and 10 representing beneficial adsorption for
BEAC, AAC, CAC and BNAC respectively[5,6]. The
adsorption capacity (kf) obtained for different adsorbents
has been comparable, among them CAC shows highest
value of adsorption capacity.
Conclusion
This work clearly indicates the potential of using
BEAC, AAC, CAC and BNAC as an excellent adsorbents
for the removal of Cu (II) ions from aqueous solutions.
The amount of Cu (II) ions adsorbed onto the BEAC,
AAC, CAC and BNAC increased with an increase in pH.
The optimum pH was found as pH 7 for the removal of
Cu (II) ions by AAC, CAC and BNAC and pH 6 for
BEAC. The BEAC, AAC, CAC and BNAC of particle
size 45-180 micron were identified to bring about
maximum adsorption percentage of Cu (II) ions. The
equilibrium data was analyzed for the Langmuir and
Freundlich isotherm model. Among these two isotherms,
Langmuir isotherm fitted well with the experimental data
than Freundlich isotherm. This confirms the monolayer
adsorption process. Taking into consideration of the
above results, it can be concluded that the BEAC, AAC,
CAC and BNAC were a suitable adsorbents for the
removal of Cu (II) ions from aqueous solution in terms of
low cost, natural and abundant availability
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In the present study, carbonized Senna uniflora (mill.) was investigated as a biosorbent for the removal of copper ions from aqueous solutions. Batch adsorption studies showed that senna uniflora(mill.) was able to adsorb Cu(II) ions from aqueous solutions in the concentration range of 100 - 200 mg L-1. The adsorption was favoured with maximum adsorption at pH 5, whereas the adsorption starts at pH 1. The effects of contact time, initial concentration of metal ions, adsorbent dosage and particle size have been reported. The applicability of Langmuir and Freundlich isotherms were tried for the system to completely understand the adsorption isotherm processes. Among these two isotherm models, the adsorption of Cu(II) ions on SUC fits very well with Langmuir adsorption isotherm which indicates the monolayer adsorption process. The carbonized senna uniflora (mill.) was found to be cost effective and has good efficiency to remove copper ions from aqueous solution.
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