Comparison function natural absorbents on Mobility of Heavy Metals (Cadmium and Lead) in Contaminated Sandy Soil

Contamination of soils with heavy metals is caused either in a natural manner or by human activities such as industrial and mining activities. Decontamination is especially important for the environment. Today, natural absorbents are used to remove heavy metals. This study aimed to study the effect of incubation time of natural absorbents (kiwi skin and silk worm cocoon) on the mobility decrease of some heavy metals such as copper (Cu) and zinc (Zn), in contaminated sandy soils. The soil was synthetically contaminated in the laboratory with multi-componet solutions. The experiments were performed in two replicates and three treatments (soil with out adding kiwi skin and silk worm cocoon (control) and soil contain kiwi skin and soil contain silk worm cocoon). The samples were kept at fixed temperature of 28oC for 3 hours, 1, 3, 7, 14, 21 and 28 days. Then, concentration of Cu and Zn were studied in soil components using sequential extraction. The results showed that The descending trend of distribution percentage of the heavy metals competing with each other in exchangeable phase in the sandy soil sample along with the kiwi skin and silk worm cocoon were as follows: Cu>Zn. After 28 days (soil with kiwi skin), (Cu) distribution in organic phase was higher than other phase and distribution of (Zn) was high in manganese and iron Phase. After 28 days (soil with silk worm cocoon), (Cu) distribution in organic phase was higher than other phase and distribution of (Zn) was high in manganese and iron Phase.