The effect of incubation time and silk worm cocoon on mobility of zinc and copper in contaminated clay soil

Document Type : Original Article


Department of Environment, School of Basic Science, Islamic Azad University, Hamedan Branch, Hamedan, Iran


Of the problematic agents in the ecosystem, heavy metals have special importance because they are unabsorbable and have physiologic effects on living beings at low concentrations. This study has investigated the effect of silk worm cocoon on reducing mobility of zinc (Zn) and copper (Cu) for the first time. To this end, 5% cocoon adsorbent was added to the studied soil, which had been contaminated with Cu and Zn in separate containers at concentration of 600 mg/l. The experiment was performed in three repeats and two treatments (with and without adsorbent). Samples were incubated at 28°C at constant humidity for 3 hours, 1, 3, 7, 14, 21, and 28 days. Then both treatments were extracted using sequential extraction method and the concentration of Zn and Cu was processed using atomic absorption spectrophotometry. The results showed that there were changes in mobility of the Zn and Cu added to soil; adding silk worm cocoon to soil increased organic phase of Zn and Cu as compared to the soil without adsorbent. Data were analyzed by SPSS software. All comparisons of the means were performed at statistical level of 5% using Student’s independent t-test. Student’s independent t-test showed that the highest significant difference (P < 0.05) was observed in the organic fraction of the Cu-Zn contaminated soil with cocoon, as compared with the Cu-Zn contaminated soil without cocoon.


1. Abbaspour M. Environmental Engineering. Tehran, Iran: Islamic Azad University Publication; 1992.[In Persian].
2. Baybordi M. Soil Physics. Tehran, Iran: The University of Tehran Publication; 1993. p. 671. [In Persian].
3. Shukla SR, Pai RS. Adsorption of Cu (II), Ni (II) and Zn (II) on modified jute fibres. Bioresour Technol 2005; 96(13): 1430-8.
4. Singh RP, Agrawal M. Effects of sewage sludge amendment on heavy metal accumulation and consequent responses of Beta vulgaris plants. Chemosphere 2007; 67(11): 2229-40.
5. Duruibe JO, Ogwuegbu MO, Egwurugwu JN. Heavy metal pollution and human biotoxic effects. International Journal of Physical Sciences 2007; 2(5):112- 8.
6. Zeng F, Chen S, Miao Y, Wu F, Zhang G. Changes of organic acid exudation and rhizosphere pH in rice plants under chromium stress. Environ Pollut 2008; 155(2): 284-9.
7. Erfanmanesh M, Afuni M. Pollution of water, soil, air. Isfahan, Iran: Arkan Publication; 2002.
8. Bolt GH, Bruggenwert MG. Soil Chemistry. Part A. Basic Elements. Philadelphia, PA: Elsevier; 1976.
9. Romic M, Hengl T, Romic D, Husnjak S. Representing soil pollution by heavy metals using continuous limitation scores. Computers & Geosciences 2007; 33(10): 1316-26.
10. Nilanjana Das RV, Karthika P. Biosorption of heavy metals-An overview. Indian Journal of Biotechnology 2008; 7: 159-69.
11. Zhou YF, Haynes RJ, Naidu R. Use of inorganic and organic wastes for in situ immobilisation of Pb and Zn in a contaminated alkaline soil. Environ Sci Pollut Res Int 2012; 19(4): 1260-70.
12. Wan Ngah WS, Hanafiah MA. Removal of heavy metal ions from wastewater by chemically modified plant wastes as adsorbents: a review. Bioresour Technol 2008; 99(10): 3935-48.
13. Mirghaffari N, Chennouf S, Gaballah I, Kilbertus G. Use of agricultural wastes for eliminating heavy metal ions from synthetic solutions. Global symposium on recycling, waste treatment and clean technology 2013; 99: 2277-86. 
14. Bailey SE, Olin TJ, Bricka RM, Adrian DD. A review of potentially low-cost sorbents for heavy metals. Water Research 1999; 33(11): 2469-79.
15. Aoyama M. Removal of Cr (VI) from aqueous solution by London plane leaves. Journal of Chemical Technology and Biotechnology 2003; 78(5): 601-4.
16. Dhakal RP, Ghimire KN, Inoue K. Adsorptive separation of heavy metals from an aquatic environment using orange waste. Hydrometallurgy 2005; 79(3-4): 182-90.
17. Dakiky M, Khamis M, Manassra A, Mer'eb M. Selective adsorption of chromium(VI) in industrial wastewater using low-cost abundantly available adsorbents. Advances in Environmental Research 2002; 6(4): 533-40.
18. Altun T, Pehlivan E. Removal of Cr (VI) from aqueous solutions by modified walnut shells. Food Chemistry 2012; 132(2): 693-700.
19. Zvinowanda CM, Okonkwo JO, Shabalala PN, Agyei NM. A novel adsorbent for heavy metal remediation in aqueous environments. International Journal of Environmental Science and Technology 2009; 6(3):425- 34.
20. Bouyoucos GJ. Hydrometer Method Improved for Making Particle Size Analyses of Soils. Agronomy Journal 1962; 54(5): 464-5.
21. Thomas GW. Soil pH and soil acidity. In: Sparks DL, Editor. Methods of Soil Analysis: Chemical methods. Madison, WI: Amer. Soc. of Agronomy; 1996.
22. Allison LE, Moodie CD. Carbonate. In: Black CA, Editor. Methods of Soil Analysis: Part 2–Chemical and Microbiological Properties. Madison, WI: American Society of Agronomy; 1965. p. 1379.
23. Lu A, Zhang S, Shan Xq. Time effect on the fractionation of heavy metals in soils. Geoderma 2005; 125(3-4): 225-34.
24. Ward NI, Reeves RD, Brooks RR. Lead in soil and vegetation along a New Zealand State Highway with low traffic volume. Environmental Pollution (1970) 1975; 9(4): 243-51.
25. Terzano R, Spagnuolo M, Medici L, Dorriné W, Janssens K, Ruggiero P. Microscopic single particle characterization of zeolites synthesized in a soil polluted by copper or cadmium and treated with coal fly ash. Applied Clay Science 2007; 35(1-2): 128-38.
26. Kim RY, Sung JK, Kim SC, Jang BC, Ok YS. Effect of calcined eggshell on fractional distribution and plant uptake of Cd, Pb and Zn in contaminated soils near mine. Brisbane, Australia: World Congress of Soil Science, Soil Solutions for a Changing World; 2010.
27. Jalali M, Khanlari ZV. Effect of aging process on the fractionation of heavy metals in some calcareous soils of Iran. Geoderma 2008; 143(1-2): 26-40. 
28. Salbu B, Krekling T. Characterization of radioactive particles in the environment. Analyst 1998; 123: 843-50.
29. Baker DE, Senft JP. Copper. In: Alloway BJ, Editor. Heavy Metals in Soils. Berlin, Germany: Springer; 1995.
30. Luo Y, Jiang X, Wu L, Song J, Wu S, Lu R, et al. Accumulation and chemical fractionation of Cu in a paddy soil irrigated with Cu-rich wastewater. Geoderma 2003; 115(1): 113-20.
31. Bartlett JR, James BR. Redox chemistry of soils. Adv Agron 1993; 50: 151-208.
32. Ramos L, Gonzalez MJ, Hernandez LM. Sequential extraction of copper, lead, cadmium, and zinc in sediments from Ebro river (Spain): relationship with levels detected in earthworms. Bull Environ Contam Toxicol 1999; 62(3): 301-8. 
33. Li Z, Shuman LM. Extractability of Zinc, Cadmium, and Nickel in Soils Amended With Edta. Soil Science 1996; 161(4): 226-32.
34. Lindsay WL. Chemical Equilibria in Soils. Caldwell, NJ: Blackburn Press; 2001.
35. Clemente R, Escolar A, Bernal MP. Heavy metals fractionation and organic matter mineralisation in contaminated calcareous soil amended with organic materials. Bioresour Technol 2006; 97(15): 1894-901.