Application of some clay minerals to eliminate the hazards of heavy metals in contaminated soils

Soil pollution by heavy metals has serious hazards on microorganism plants, human being and ecological environment. Many approaches have been introduced to overcome the problem of contaminated soils by heavy metals as cadmium, copper and nickel. A laboratory experiment conducted using zeolite and bentonite, three rates on contaminated soils (sandy and clay) with 200ppm of each element. The adsorption and release of element by time (1-14 days) have been recorded. The rate constants of Hoerl's and Elovich kinetic models were determined to compare the effect of adding zeolite and bentonite in three rates on sandy and clay soils. The obtained results indicated that the reaction occurs very fast after adding the remediation material and continuous steady by time. The low rate of the material was very effective in increasing the adsorption of the heavy metals. The release of elements as a result of adding both zeolite and bentonite had the order Cd2+ > Cu2+ > Ni2+. The role of zeolite is more pronouncing in enhancing the adsorption of the heavy metals more than bentonite due its specific molecular structure and high surface area. Therefore it recommended to be applied as a remediation material in polluted soils by heavy metals.