REMOVAL OF CHROMIUM (VI) BY ACTIVATED CARBON DERIVED FROM MANGIFERA INDICA

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IJRET: International Journal of Research in Engineering and Technology
eISSN: 2319-1163 | pISSN: 2321-7308
REMOVAL OF CHROMIUM (VI) BY ACTIVATED CARBON
DERIVED FROM MANGIFERA INDICA
Shashikant.R.Mise1, Sugunashree.S.M2
1Professor, Department of Civil Engineering, 2M.Tech Scholar, Department of Environmental Engineering,
PDA College of Engineering Gulbarga
[email protected], [email protected]
Abstract
The removal of chromium (VI) from synthetic sample by adsorption on activated carbon prepared from Mangifera Indica (mango)
seed shell have been carried out at room temperature 32 1 C. The removal of chromium (VI) from synthetic sample by adsorption
on chemical activation (Zinc chloride) with Impregnation ratio's (I.R) 0.25, 0.50, 0.75 for optimum time, optimum dosages and
variation of pH was studied. It is observed that as dosage increases the adsorption increased along with the increase in Impregnation
ratio. It was also noted that as I.R. increases the surface area of Mangifera Indica shell carbon increased. Hence the maximum
removal efficiency is obtained at I.R ratio of 0.75. The optimum contact time, dosage and pH for carbon with I.R-0.75 was 40min,
150mg and 1.50 with removal efficiency of 99.00%, 99.20% and 99.60% respectively.
Keywords: Chromium (VI), Contact time, Dosage, Kinetics, pH, Mangifera Indica.
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1. INTRODUCTION
a suitable adsorbent for treatment of chromium contaminated
water.
Chromium is a common pollutant introduced into natural
waters due to discharge of variety of industrial wastewaters, is
2.1.1 Characteristics of Mangifera Indica (Mango)
highly toxic and presents a serious threat to human health and
environment. Chromium is considered as one of the top 16th
Shell Carbon:
toxic
pollutants and
because
of its
carcinogenic
and
teratogenic characteristics on the public, it has become a
Before using the Mangifera Indica (mango) seed shell carbon
serious health concern. According to the world health
as an adsorbent, the characteristics such as moisture content,
organization (W.H.O) drinking water guidelines and ISO-
ash content, pH, decolorizing power, surface area, specific
10500, the maximum allowable limit for total chromium is
gravity and bulk density of the prepared carbon are studied.
0.05mg/L.[3]
The results are shown in Table-1
All the methods of analysis are as per "
1.1 Objectives of the Study:
Standard Methods for
the Examination of Water and Wastewater", 19th edition [1].
The present study has been carried out with the following
objectives: The preparation of chemically activated carbon by
Table-1 Characteristics of Prepared Activated Carbon
using Zinc chloride as an activating agent, to study the
physico-chemical properties of the prepared carbon, and
Chemically activated
Detection of chromium (VI) removal as a function of contact
Sl.
Characteristics
ZnCl
time, dosage and pH.
No.
2
0.25
0.50
0.75
2. MATERIALS AND METHODS
Moisture content
1
18.00
20.00
20.50
(%)
2.1 Material
2
Ash content (%)
20.37
23.75
24.52
The material used for preparing carbon was Mangifera Indica
(Mango) seed shell. The scientific name of this fruit is
Decolorizing
3
27.00
28.50
31.50
Mangifera Indica, from family Anacardiaceae. Activated
power, (mg/g)
carbon made from mango seed shell does not impart any
Surface area,
4
505.84
859.94
935.81
colour, taste and odour to water, when it is added to it. So it is
(m2/g)
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eISSN: 2319-1163 | pISSN: 2321-7308
6.6
5.5
5.1
To determine the optimum dosage of activated carbon,
5
pH
adsorbent is added to the conical flask in different dosage
varying from (25mg, 50mg, 75mg up to 300mg), containing
6
Specific gravity
0.568
0.698
0.865
100ml of 0.5 mg/L concentration of chromium (VI) solution
Bulk Density,
7
0.423
0.423
0.406
and pH is adjusted to 2.00.02. The solution in the conical
(g/cm3)
flask is subjected to stirring for pre-determined optimum
contact time, filtered and analyzed for residual chromium
2.2 Methods
concentration.
2.2.1 Preparation of Activated Carbon Using Zncl2 as
The dosage which gives minimum residual concentration is
Activating Agent:
chosen as optimum dosage.
The known quantity of washed and dried Mangifera Indica
2.2.6 Selection of Optimum pH on Hexavalent
(Mango) shell powder of size 300 Micron was mixed with the
activating agent (ZnCl
Chromium:
2), in required quantity, depending upon
the impregnation ratio (I.R).
The extent of adsorption is strongly influenced by the pH at
which adsorption is carried out. The effect of pH on

Impregnation ratio (I.R) =
hexavalent chromium adsorption was studied by performing

equilibrium adsorption tests at different initial pH values. i.e.
The carbonising material was filled in the small container in
from 1.25 to 3.0 at an interval of 0.25. The pH of solution was
three layers, by compacting each layer without any air space to
adjusted by using 0.1N H2SO4 or 0.1N NaOH. The maximum
avoid the loss in weight of the powder. The small container is
concentration of chromium (VI) removal forms optimum pH.
then placed into a big container, such that sand surrounded the
small container completely, the lid of the big container was
3. RESULTS AND DISCUSSIONS
tightly fitted. Pin hole has been made on the lids of the
The efficiency of removal of hexavalent chromium is studied
containers for the escape of organic vapours. Then the setup is
in terms of: Effect of contact time, Effect of dosage and Effect
kept in Muffle furnace and heated at steady rate to attain the
of pH.
temperature of 800oC. Thirty minutes after attaining the 800oC
temperature the furnace was allowed to cool for about 10
3.1 Effect of Contact Time:
hours and then the container is taken out. Activated carbon
thus prepared was washed with 0.1N HCl to remove the
Contact time has greater influence in the adsorption process.
activating agent, followed by hot distilled water for about 8
The effect of contact time on removal of chromium (VI) from
times to remove the excess HCl present in the activated
synthetic sample at pH 2 0.02 using chemically activated
carbon. The activated carbon was dried at 1055oC then
carbon with I.R. 0.25, 0.50 and 0.75 are shown in figure 1. As
packed in polythene bags and kept in desiccators.[2]
I.R. increases optimum time decreases due to the increase in
surface area. Optimum contact time for all prepared carbons is
2.2.3 Batch Sorption Experiment
listed in table-2.
In batch sorption, a pre-determined powder of adsorbent is
mixed with the sample, stirred for a given contact time and
120
subsequently separated by filtration. Powder adsorbent is more
I)
suitable for the batch type contact process.
V 100
(r
2.2.4 Selection of Optimum Contact Time:
C 80
of
IR- 0.25
The adsorption is strongly influenced by the contact time. To
60
study the effect of contact time, 100ml of 0.5mg/L hexavalent
oval
IR- 0.5
40
chromium solution of pH 2.00.02, was mixed with 0.1g of
em
IR- 0.75
activated carbon, stirred at different contact times varying
R 20
from (5mins, 10mins, 15mins up to 60mins). Then filtrate was
%
analyzed for residual chromium (VI) concentration using
0
spectrophotometer.
0
20
40
60
80
Time in minutes
2.2.5
Determination
of
Optimum
Dosage
of
Adsorbent:
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Fig.1. Effect of Contact Time on Cr (VI) Removal by ZnCl2
activated carbon
102
100
I)
3.2 Effect of Adsorbent Dosage:
98
(V
Effect of adsorbent dosage is studied and graph of percentage
96
Cr
of residual chromium removal versus dosage is plotted as
94
of
shown in figure 2. From the graph it is observed that, as the
IR = 0.25
dosage of carbon increases, amount of residual chromium (VI)
92
oval
decreases sharply and attains equilibrium. The dosage at
90
IR = 0.50
m
which maximum removal is attained, is taken as optimum
88
Re
IR = 0.75
dosage. After this not much change is observed even after
increase in the amount of carbon dosage. The optimum dosage
86
%
for all prepared carbon are listed in table-2
84
0
1
2
3
4
120
pH
100
I)
(V
Fig.3.Effect of pH on Cr (VI) Removal by ZnCl2 Activated
80
Cr
Carbon
of60
Table2. Optimum Time, Optimum Dosage and Optimum pH
IR = 0.25
for Prepared Carbons
oval40
m
IR = 0.50
Initial concentration = 0.5 mg/L
pH = 2 0.02
Re20
IR = 0.75
%
Volume of sample
= 100mL
Temperature = 32 1 C
0
Optimum
Optimum
0
100
200
300
400
Type
Of
Optimum
I.R
Time
Dosage
Carbon
pH
Adsorbent Dosage in mg
(min)
(mg)
Chemically
0.25
50
225
1.5
activated
Fig.2.Effect of Adsorbent Dosage on Cr (VI) Removal by
0.50
45
200
1.5
ZnCl2 activated carbon
(ZnCl2)
0.75
40
150
1.5
3.3 Effect of pH on Hexavalent Chromium Removal:
CONCLUSIONS
The pH of solution has influence on the extent of adsorption
removal efficiencies of chromium (VI) by prepared activated
Based on the experimental study the following conclusions
carbon at different pH values are shown in figure 3. From the
were drawn: The extent of chromium adsorption increases
figure, it is observed that chromium (VI) is removed more
with increase in time and attain equilibrium. The result of
effectively in acidic range. As pH increases, the removable
experiment on optimization of dosage of adsorbent reveals
efficiency
decreases
appreciably.
This
is
due
to
the
that increase in amount of adsorbent added, increases the
precipitation of carbon surface by nucleation. The optimum
removal of Cr (VI) from the solution and almost becomes
pH for all prepared carbon are listed in table-2
constant after saturation dose for different I.RS. The removal
of Cr (VI) increases mainly due to the enhanced total surface
area of the adsorbent. And the adsorption of Cr (VI) is pH
dependent. The removal efficiency of adsorbent increases with
decrease in the pH value.
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IJRET: International Journal of Research in Engineering and Technology
eISSN: 2319-1163 | pISSN: 2321-7308
REFERENCES
[1]
APHA, "Standard Methods for the Examination of
Water and Wastewater", 19th edition (APHA, AWWA,
and WFF Washington DC) (1995) pp 3.58-3.60.
[2]
K.Swarna Lata, "Adsorption Studies of Cr (VI) on
Activated
Carbon
Derived
from
Royal
Poinciana
(Gulmohar) Shell". M.Tech. Env. Engg. Dissertation
Work, P.D.A.C.E.G, (2005-2006).
[3]
WHO, (1963), Guidelines for drinking-water quality,
World Health Organization, Geneva
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