Competitive Sorption of Cu, Pb, Cd, and Ni on Soil Clay Minerals adjacent to the Cement Factory Ilam city

Soil pollution and accumulation of heavy metals is one of the most important environmental issues threatening plants, animals and humans being. The aim of this research is to study the sorption of heavy metals of copper, lead, nickel and cadmium by soil clay particles around Ilam cement factory. This research was carried out based on the topographic maps, field examinations and satellite images of the Earth, and 5 soil profiles were drilled in the agricultural land, forest and pasture. Soil samples were taken from the surface and subsurface horizons of the profiles, as well as from the factory's output dust in different months, and the amount of heavy metals was measured by the atomic absorption spectroscopy. Clay mineralogy was studies using x-ray diffraction method (XRD). In order to separate the clay particles standard sieve series was applied. The sorption of metals by the clay samples was performed using a mixed solution of multi metals in three replicates (21 samples), and 7 different concentrations of nitrate salts of copper, lead, cadmium, and nickel. The results showed that vermiculite, illite, kaolinite and chlorite were formed in fine clay minerals and kaolinite, illite and chlorite in coarse clay minerals. The amount of heavy metals in the soil samples around the factory, as well as in the factory's output dust, was less than the global standard, so it can be said that the Ilam Cement Factory did not have a significant impact on the pollution of the region. Competitive adsorption results showed that in all concentrations the sorption of copper metal by the clay particles was high, but nickel was low, Meanwhile, in higher concentrations (80 and 100 mg/l) sorption of cadmium and lead showed a sharp decrease. Generally the results revealed that, the amount of metal sorption is reduced as follows: Cu> Pb> Cd> Ni.