Papaya Seed

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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.



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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

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



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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


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.


adsorbed onto carbonized Carica papaya seeds


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


adsorbed onto raw Carica papaya seeds


of Cd2+

(ppm)

Final concentration

of Cd2+

(ppm)

Amount 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


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



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Table 8: The percentage of Cr6+

adsorbed onto carbonized Carica papaya seed


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

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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

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