International Journal of Engineering Trends and Technology (IJETT) –Volume2 issue3Number 2–Dec2011
ADSORPTION OF CHROMIUM (VI) FROM AQUEOUS SOLUTION
USING SUGARCANE BAGASSE AS ADSORBENT
SARITHA.B1, ABHISHEK SINGH2, AMSON3, DHIRAJ JHA4, KHRIEZO KISO5
1
Assistant Professor,Department of civil engineering,Bharath University,
2,3,4,5
Department of civil engineering,Bharath University,Selaiyur, Chennai-73,
INDIA.
Abstract: - The study was undertaken to investigate the removal of Cr(VI) collected from sugarcane
baggase by adsoption process. Batch adsorption study determines that sugarcane bagasse has a
significant capacity for adsorption of Cr(VI) from aqueous solution. The parameters used in these
study includes contact time, adsorbent dosage, pH, concerntration. The maximum adsorbent loading
of CR(VI) was found to be 0.5gm/100ml for maximum removal of Cr(VI) ion of 50 mg/l of initial
concentration. Adsorption capacity is 5.25 mg/g for adsoption of Cr(VI).
Key-Words: - Cr(VI), adsorption, adsorbent, sugarcane bagasse
1 Introduction
One of the serious environmental issues is the
presence of toxic heavy metals contaminants in
aqueous streams, arising from the discharge of
untreated metal containing effluents into water
bodies. Disposal of heavy metals in ground by
human activity is nowadays increased due to
urbanization,
combustion
byproducts,
automobile emissions, mining activities.
Disposed heavy metals are not biodegradable
substances and they tend to accumulate in living
organism causing various disease and disorder
(Bailey et al.,1999)[1]. Among the toxic heavy
metals, chromium in its hexavalent form is
known to cause wide ranging human health
effect including mutagenic and carcinogenic
risks (Park and Jung, 2001)[2].
Chromium is widely used in electroplating,
leather tanning, metal finishing and chromate
preparation and are usually present in high
concentration in the aqueous waste which are
usually released directly into the environment
without any pretreatment. The commonly used
techniques includes chemical precipitation,
reverse osmosis, evaporation, ion exchange and
adsorption of which adsorption has proved to be
very effective. Because of their high surface
area and high porous character, activated
carbons have been considered as potential
ISSN: 2231-5381
adsorbents for Cr(VI) (Jianlong et al., 2000)[3].
Due to the relatively high cost of activated
carbon, there is a need to produce low cost
adsorbent for Cr(VI) removal from cheap and
readily available materials which can be used
economically on a large scale.
The aim of this study is to investigate the use
of sugarcane bagasse in the removal of Cr(VI)
from aqueous solution. The study involves the
examination of experimental conditions such as
pH of the solution, concentration of the
solution, contact time and adsorbent loading on
the removal of Cr(VI) from aqueous solution.
The Freundlich and Langmiur adsorption
isotherms were used to investigate the
adsorption process.
2 Materials and Methods
2.1 Adsorbent Preparation
The sugarcane bagasse was obtained from the
stalls nearby and was washed with tap water
and dried in the sun. Then the sugarcane
bagasse was washed repeatedly with distilled
water to remove dust and insoluble impurities
and dried in the oven at 106˚C for 2 hours. Then
they were crushed and sieved through 1.18mm
http://www.ijettjournal.org
Page 1
International Journal of Engineering Trends and Technology (IJETT) –Volume2 issue3Number 2–Dec2011
and 600microns sieve. The powdered sugarcane
bagasse passing through 1.18mm and retained
on 600microns sieve was collected and washed
with distilled water until washings are free from
colour and pH of solution was 7.
The concentration of Cr in adsorbent was
determined by placing 2g of adsorbent in 20ml
distilled water for 1 hour with continuous
agitation, after which it was centrifuged with
laboratory centrifuge. The supernatant was
carefully decanted and analysed using AAS
(Atomic Absorption Spectrophotometer).
2.2 Adsorbate solution
Stock solution of Cr(VI) was prepared by
dissolving 1.41g of K2Cr2O7 in 100ml distilled
water. The solution was diluted as required to
obtain standard solutions.
Q=
XV
(1)
Sorption efficiency (%) =
ISSN: 2231-5381
(2)
Qe = adsorbent phase concentration after
equilibrum.mg adsorbate /g.adsorbent
Co = initial concentration of adsorbate (mg/l)
Ce = final equilibrium concentration of
adsorbate after absorption has occurred (mg/l)
M = mass of adsorbent
V = volume in litres
2.4 Adsorption isotherms
The Freundlich and Langmiur adsorption
isotherm models were used. The Freundlich
isotherm (Fruendlich, 1906)[5] is expressed as
Log Qe = Log Kf + (1/n)Log Ce
2.3 Batch adsorption experiments
Batch adsorption experiments were conducted
by agitating the standard solution for 30
minutes in jar test apparatus. Experiments were
carried out by varying the adsorbent amount
from 0.2gm/100ml to 1.6gm/100ml solution
with a Cr (VI) concentration of 50mg/l.
Adsorption isotherm study was carried out with
different initial concentration of chromium (VI)
from 10-80mg/l while maintaining the
adsorbent dosage at 0.4gm/100ml. Then the
effect of time and pH was studied with Cr (VI)
concentration of 50mg/l and adsorbent dosage
of 0.4gm/100ml. The aqueous solution pH was
adjusted in the range of 2-12 by using d0iluted
H2SO4 and NaOH solution. The concentration
of free Cr (VI) ions in the effluent was
estimated spectrophotometrically at 540nm
using 1,5-dipheny carbazide method (APHA,
2
1985)[4]. R (regression coefficient square
value) and isotherm constants values were
determined from the graph.
The amount of metal ion adsorbed per
gram of biomass and the sorption efficiency (%)
were calculated according to the expressions:
X 100
(3)
Where; Kf = Freundlich constant indicative of
the relative sorption capacity of the adsorbent
n = Freundlich constant indicative of the
intensity of sorption.
The Langmiur isotherm (Langmiur,
1918)[6] is expressed as
Ce/Qe = 1/Qmb + Ce/Qm
(4)
Where Qm (mg/g) and b are Langmuir constants
related to adsorption capacity and the energy of
biosorption, respectively.
3 Results and discussions
3.1 Effect of adsorbent dosage
The effect of adsorbent dosage on the
adsorption of Cr(VI) process is shown in Fig 1.
It is clearly indicated that the removal of Cr(VI)
increased with increase of adsorbent dosage.
However, the adsorption capacity showed a
decreasing trend with increasing dosage.
Adsorption capacity was maximum at 0.4g/L.
The drop in adsorption capacity is basically due
http://www.ijettjournal.org
Page 2
to sites remaining unsaturated during the
adsorption reaction.
3.2 Effect of Contact time
The adsorption of Cr(VI) on time is presented
in Fig. 2. It is apparent from that the percentage
removal increases with increasing contact time
and the equilibrium was obtained after 50
minutes. Therefore, the adsorption for 50
minutes could be considered for whole batch
experiments. The agitation speed was 150
r.p.m.
120
% Removal of chromium
100
90
80
70
60
50
40
30
20
10
0
10
100
80
60
40
20
30
40
50
60
70
80
Contact time (in minutes)
Fig. 2 Effect of contact time on removal of
Cr(VI) ions
120
% Removal of chromium
3.3 Effect of pH
The effect of pH on the process is presented in
Fig 3. The percentage adsorption of Cr(VI) is
decreasing with increasing pH. The maximum
adsorption took place in the pH range 3-4.
% Removal of chromium
International Journal of Engineering Trends and Technology (IJETT) –Volume2 issue3Number 2–Dec2011
20
100
80
60
40
20
0
2
4
6
8
10
12
pH
0
0.2 0.4 0.6 0.8
1
1.2 1.4 1.6
Adsorbent dosage (gms)
Fig. 1 Effect of adsorbent mass on the
adsorption capacity of Sugarcane bagasse
Fig. 3 Effect of pH on removal of Cr(VI) ions
3.4 Adsorption isotherm
3.4.1 Langmiur adsorption isotherm
The linear plots of the Langmiur graph shows
us that the adsorption obeys Langmiur
adsorption isotherm as shown in Fig. 4. Qm and
b were determined from the slope and intercept
of the plot and presented in Table 1. RL,
defined by (Hall et al, 1966)[7].
ISSN: 2231-5381
http://www.ijettjournal.org
Page 3
International Journal of Engineering Trends and Technology (IJETT) –Volume2 issue3Number 2–Dec2011
RL =
(5)
Where
Co
is
the
initial
metal
concentration(mg/l) and b is the Langmiur
constant (1/mg). RL values obtained for Cr(VI)
adsorption are greater than zero and less than
unity showing favorable adsorption of Cr(VI).
Linear plots of Log Qe vs Log Ce shows that the
adsorption follows Freundlich isotherm model
as shown in Fig. 5. Kf and n calculated from the
slope and intercept of the plots were found to be
5.02 and 1.4345 respectively. According to
Treyball (1980)[8] the values of n between 1
and 10 is considered as a good adsorbent.
Therefore sugarcane bagasse which has an n
value of 1.4345 implies effective adsorption.
Table 1 The values of RL for adsorption of
Cr(VI) on sugarcane bagasse
Qm
(mg/g)
b
(1/mg)
Initial Cr(VI)
concentration
Co (mg/l)
RL
14.79
0.716
10
20
30
40
0.1225
0.0652
0.044
0.033
50
60
70
0.027
0.022
0.019
80
0.017
0.8
0.7
0.6
0.5
0.4
Log 0.3
Qe
0.2
0.1
0
-0.1 0
-0.2
y = 0.697x - 0.700
R² = 0.717
0.5
1
1.5
2
Log Ce
Fig. 5 Freundlich adsorption isotherm
y = 0.067x - 0.094
R² = 0.859
6
5
4
Qe/C 3
e
2
1
0
0
50
100
Ce
Fig. 4 Langmiur adsorption isotherm
4 Conclusion
From the present study, it can be concluded that
the sugarcane bagasse has a moderate potential
to remove chromium (VI). The percentage
removal of Cr (VI) depends on adsorbent dose,
pH, contact time, and initial Cr (VI)
concentration. At 50 minutes contact time and
initial metal concentration of 50 mg/L, 70.2%
Cr (VI) removal was observed but when the
metal concentration was increased to 50 mg/L
the removal efficiency dropped to 30.8%.
Sugarcane bagasse adsorbed chromium ions
best at lower Cr (VI) concentration in the range
of 40 to 50 mg/L but the removal efficiency
dropped to 19% when the metal concentration
was increased to 70 mg/L.
3.4.2 Freundlich adsorption isotherm
References:
ISSN: 2231-5381
http://www.ijettjournal.org
Page 4
International Journal of Engineering Trends and Technology (IJETT) –Volume2 issue3Number 2–Dec2011
[1] Bailey, JE & Ollis, DF 1986, Biochemical
Engineering Fundamentals, Mc-Graw-Hill
Book Company, Singapore.
[2] Park S and Jung WY (2001) Removal of
chromium by activated carbon fibres plated
with copper metal. Carbon Sci, 15-21.
[3] Jianlong Wang et al. (2000) Biosorbents for
heavy metal removal and their future,
Elsevier, biotechnology advances
[4] APHA, AWWA and WEF (1992) Standard
Methods for the Examination of Water and
Wastewater, 18th ed. American Public
Health Association, Washington, DC.
[5] Freundlich H (1907). Veber die adsorption
in loesungen (Adsorption in solution ) Z.
Phys. Chem., 57: 385-470.
[6] Langmuir I (1918). The adsorption of gases
on plant surfaces of glass, mica and
platinum J. Am. Chem. Soc., 40: 13611368.
[7] Hall KR, Eagleton LC, Acrivos A and
Vermeulen T (1966) Pore and solid
diffusion kinetics in fixed bed adsorption
under constant pattern condition, Ind. Eng.
Chem. Fundam. 5,212-223
[8] Treyball RE (1980) Mass transfer
operations. 3 rd ed, McGraw Hill, New
York.
ISSN: 2231-5381
http://www.ijettjournal.org
Page 5