8/20/2019 Papaya Seed
http://slidepdf.com/reader/full/papaya-seed 1/4
17
Continental J. Water, Air and Soil Pollution 3 (1): 17 – 20, 2012 ISSN: 2251 – 0508
© Wilolud Journals, 2012 http://www.wiloludjournal.com
` Printed in Nigeria doi:10.5707/cjwasp.2012.3.1.17.20
ADSORPTION OF CADMIUM AND CHROMIUM USING ACTIVATED CARBON DERIVEDFROM CARICA PAPAYA SEED.
Ayeni K. E.
Department of SLT, Federal Polytechnic Offa, P.M. B 420 Offa, Kwara State, Nigeria.
Email: [email protected]
ABSTRACT
Heavy metals such as Cadmium and Chromium are toxic and may be found in both surface and
underground water. Carica papaya seed which is an agricultural wastes comprising mostly cellulose
materials was used for the removal of these toxic metals from aqueous solutions. Activated carbons
were prepared from Carica papaya seeds with particle sizes ranging from 355 – 835 um. 0.10M H3PO4
and ZnCl2 were each used for chemical activation at 3 minutes residence time and at 7500C. This was
after carbonizing the source material at 5000C and also residence time of 5 minutes. The adsorption of
cadmium and chromium from aqueous solution onto zncl2 and H3PO4 activated carbons was studied and
assessed for the possibility of using the source materials for the removal of heavy metals from aqueous
solution. The effect of varying the particle size of the activated carbons and the type of activating agents
on the adsorption capacity were well as for the carbonized or raw materials. Little adsorption took place
when raw material was used for the adsorption of the metals. The results indicated that the activity of
0.10M H3PO4 and 0.10M ZnCl2 activated carbons with particle size of less than 355um gave the highest
adsorption capacities; with ZnCl2 activated carbons exhibiting better adsorption capability than H3PO4
– activated carbons. This work has shown that Carica papaya seed can be used to remove these two
metals from aqueous solution.
KEYWORDS: Activated carbon, H3PO4 – activated carbons, ZnCl2 activated carbons
INTRODUCTION
Since some heavy metals such as lead, cadmium, chromium, zinc, copper etc are toxic and may be found in both
surface and underground water. A wide variety of Agricultural by product and agricultural wastes comprising
mostly cellulose materials were tried by different works for the removal of toxic metals from aqueous solutions.
This include cassava fibre, (1) Biomass of fungi and yeast (2), Horse shoe sea crab shell (3) rice husk (4) saw dust (5)
etc However, a comprehensive list of naturally occurring adsorbents for removal of dyes and heavy metals can
be obtained from(6)
However factors such as physical and chemical characteristics of the adsorbate e.g.
molecular size, molecular polarity, chemical composition, residence time of the system, temperature and surface
area of the adsorbent e.t.c. affects adsorption of cations from aqueous solution (7) The purpose of this work is to
evaluate the adsorption capacity of activated carbon from Carica papaya seed on some toxic metals, that is,
activated carbon will be prepared from Carica papaya seed and will be used to check the removal or adsorption
of cadmium and Chromium ions from aqueous solution. It is also the intention of this work to compare and
establish the ability of H3PO4 and ZnCl2 as activating agents for the purpose of producing activated carbon fromCarica papaya seeds.
EXPERIMENTAL
Materials
Carica papaya seed were collected from different markets in Zaria and Kano, Nigeria. They were washed, air
dried, grinded and sieved into particle sizes of less than 355, 425 and 834µm. All other reagents are of analytical
grade were used without further purification.
8/20/2019 Papaya Seed
http://slidepdf.com/reader/full/papaya-seed 2/4
18
Ayeni K. E: Continental J. Water, Air and Soil Pollution 3 (1): 17 – 20, 2012
Procedure for Carbonization and Activation.
The sample were carbonized and activated by the two steps method(8)
. 2.00g of raw carica papaya seed sample
was weighed into reweighed crucibles and placed in a carbolite furnance at 5000C for 3 minutes to carbonize it.
Adsorption of Calcium and Chrominum using Activated Carbon Derived from Carica papaya Seed
500OC, 3 minutes
Raw – Carica papaya seeds C(s) + CO2 (CARBONIZATION)
△
AA, 750OC, 5 minutes
Carbonized- Carica papaya AC + CO2 (ACTIVATION)
△
Where “AA” represents Activating Agent and “AC” represents Activated Carbon. The above processes were
repeated until a substantial amount was obtained. It was allowed to cool in H2O and allowed to dry at room
temperature and stored in dry polythene bags.
Preparation of 0.10M solution of H3P04. 0.10M of H3P04 was prepared by diluting 1.70cm3 of H3P04 in 250cm3 volumetric flask with distilled water.
Preparation of 0.10M ZnCl20.10M of ZnCl2 was prepared by dissolving 3.40g of salt in 250cm3 volumetric flasks with distilled H2O.
Preparation of standard concentration of Cd2+
and Cr6+.
1000ppm of Cr6+ was prepared by dissolving, 1.867g of K2Cr2O4 in 250cm3 distilled water and it was later
diluted to 500cm3 in a 500cm
3 volumetric flask. 000ppm Cd
2+ was prepared by dissolving 1.0516g of Cd (NO3)2
in about 250cm3 distilled water and it was later diluted to 500cm3 in a volumetric flask.
Test for Cd2+
and Cr6+
adsorption
1.00g each of the raw materials, the carbonized and the activated samples was weighed into 250cm3 conical
flask. 50cm3 of the 1000ppm stock solution of Cd2+ and Cr6+ was added. Each mixture was shaken thoroughlywith a Griffin model electric shaker for an hour to attain equilibrium. Thereafter, the different supernatant were
filtered and the concentration remaining in the filtrate were determined using JENWAYS Atomic Absorption
Spectrophotometer
RESULTS AND DISCUSSIONTable1: The percentage of Cd2+ adsorbed onto Carica papaya seeds activated with ZnCl2
Initial concentration of
Cd2+
(ppm)
Sss
Final concentration of
Cd2+
(ppm)
Amount of Cd2+
adsorbed (ppm) % of Cd2+
adsorbed
Particle
size (um)
1000 80.00 920 92.00 < 355
1000 390.00 610 61.00 425
1000 548.40 451.60 45.16 835
Table 2: The percentage of Cd2+ adsorbed onto Carica papaya seeds activated with H3PO4
Initial
concentration of
Cd2+
(ppm)
Final concentration
of Cd2+ (ppm)
Amount of Cd +
adsorbed (ppm) % of Cd2+
adsorbed
Particle size
(um)
1000 147.10 852.90 85.29 < 355
1000 358.40 641.60 64.16 425
1000 467.70 532.30 53.32 835
8/20/2019 Papaya Seed
http://slidepdf.com/reader/full/papaya-seed 3/4
19
Ayeni K. E: Continental J. Water, Air and Soil Pollution 3 (1): 17 – 20, 2012
Table 3: The percentage of Cd6+
adsorbed onto Carica papaya seeds activated with ZnCl2
Initial concentration
of Cr6+
(ppm)
Final concentration
of Cr6+
(ppm)
Amount of Cr+
adsorbed (ppm)
% of Cr+ adsorbed Particle size (um)
1000 483.40 516.60 51.66 < 355
1000 638.90 361.10 36.11 425
1000 713.20 286.80 28.68 835
Table 4: The percentage of Cr6+ adsorbed onto Carica papaya seeds activated with H3PO4
Initial concentration
of Cr6+
(ppm)
Final concentration
of Cr6+
(ppm)
Amount of Cr +
adsorbed (ppm)
% of Cr +
adsorbed
Particle size (um)
1000 389.80 510.20 71.02 < 355
1000 436.20 361.10 36.11 425
1000 553.10 286.80 28.68 835
Table 1 and 2 show that the percentage of Cd2+ adsorbed onto Carica papaya seeds carbon activated with ZnCl2
and H3PO4 respectively. The result shows that ZnCl2 has better activating activity than H3PO4. The adsorbed of
Cd2+
in the aqueous solution increases with decreases in particle size. This may be explained as a result of
increase in surface area with decrease in particle size producing a large surface area for adsorbed of cadmium in
aqueous solution. This is in agreement with studies by {8,9}. More so similar observation was also observed in the
case of Cr6+
adsorption from aqueous solution using H3PO4 and ZnCl2 activated Carica papaya seeds as shown
on Table 3 and 6, but in this case the result shows that H3PO4 has better activating activity than ZnCl2.
Table 5: The percentage of Cd2+
adsorbed onto carbonized Carica papaya seeds
Initial concentration
of Cd2+ (ppm)
Final concentration
of Cd2+ (ppm)
Amount of Cd2+
adsorbed (ppm) % of Cd2+ adsorbed
Particle size (um)
1000 732,70 267.30 26.73 <3551000 848.90 151.10 15.11 429
1000 887.40 112.60 11.26 835
Table 6: The percentage of Cd2+
adsorbed onto raw Carica papaya seeds
Initial concentration
of Cd2+
(ppm)
Final concentration
of Cd2+
(ppm)
Amount of Cd2+
adsorbed (ppm) % of Cd2+
adsorbed
Particle size (um)
1000 917.70 82.30 8.32 <355
1000 943.20 56.80 5.68 425
1000 969.90 30.10 3.01 835
Table 7: The percentage of Cr6+ adsorbed onto carbonized Carica papaya seeds
Initial concentration
of Cr6+
(ppm)
Final concentration
of Cr6+
(ppm)
Amount of Cr +
adsorbed (ppm)
% of Cr + adsorbed Particle size (um)
1000 887.90 112.10 11.21 <355
1000 936.20 638.00 6.38 425
1000 967.80 32.20 3.22 835
8/20/2019 Papaya Seed
http://slidepdf.com/reader/full/papaya-seed 4/4
20
Ayeni K. E: Continental J. Water, Air and Soil Pollution 3 (1): 17 – 20, 2012
Table 8: The percentage of Cr6+
adsorbed onto carbonized Carica papaya seed
Initial concentration
of Cr6+
(ppm)
Final concentration
of Cr6+
(ppm)
Amount of Cr+
adsorbed (ppm)
% of Cr+ adsorbed Particle size (um)
1000 913.90 86.10 8.61 <3551000 956.70 43.30 4.33 425
1000 972.40 27.60 2.76 835
Table 5,6,7,8 show control experiments. The carbonized samples and the raw forms of various particle sizes
were used for the adsorbed or raw samples with similar particle sizes could exhibit similar to the activated
samples. Table 5,6,7,8, show low affinities for metals uptakes in aqueous solution when compared to that of
carbonized and activated ones. The raw sample has no sufficient exposed structure as compared to thecarbonized ones because molecular architecture of the surface has been altered during carbonization and
subsequent activation.
CONCLUSION
Carbon prepared from Carica papaya seed can be a good source of raw material toward utilization as a cheap
and alternative source of commercial carbon that can be used for the recycling of heavy metals waste water. Theactivated samples treated with H3PO4 and ZnCl2 gave higher adsorption of Cd2+ and Cr6+ when compared to the
carbonized and raw samples.
REFERENCES
James, M. Okuno, J.M., Oviawe, A.P. (2007). Selective sorption of mixed heavy metal ions using cassava Fibermodified with citric acid. J. Chemical Society of Nigeria, 33 :243-253.
Kumud, K. and Emilia, A. T. (2007). Biosorption of anionic textile dyes by ion viable biomass of fungi and
yeast. Bioresource Technology, 98: 1704-1710.
Gullen, J., Aroguz, A.Z., Dalgin, D, (2004). Adsorption kinetic of azinphosmethyl from aqueous solution ontopyrolyed Horse show sea crab shell from Atlantic ocean. Bioresource Technology, 96:1169-1174.
Wuana, R. A., Okieimen F. E., Amua, Q.m. (2005). Aqueous phase adsorption of organics on rice husk bases
activated carbon modified with malic
Argun, K. N., Dursun, S., Ozdemis, C., Kanatas, M. (2007) Heavy metal adsorption by modified Oak Sawdust:thermodynamics and Kinetics. Hazard materials, 141: 77-87.
Bailey, G., white, J. L. (1970). Factors influencing the adsorption and movement of pesticides in soil. Residue
Development , 32:29-92.
Cheremisnoff, P., and Ellerbusch, F. (1978). Carbon adsorption handbook. Ann Anbor Science Publisher Inc
72,pg 689-690.
Gimba, C. E., and Bahago N. A. (2004). Adsorption of Cu, Cd, and Cr using activated carbon derived fromArachis hypogaea shells. CHEMCLASS J . pg208-213.
Salami, N and Adekola, F. A. (2002). Bulletin of Chemical Society of Ethiopia, 1:5-10.
Received for Publication: 04/02/2012
Accepted for Publication: 08/04/2012