Ramin Samieifard - Department of soil sciences, Faculty of Agriculture & Natural Resources, University of Tehran, Karaj, Iran
Ahmad Landi - Department of soil science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran
Nahid Pourreza - Department of Chemistry, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran

Nowadays, removal of heavy-metal contaminants from industrial waste waters is one of the most important environmental polemics which necessarily requires a solution. Clays, because of their low cost and unique chemical and structural properties have been widely used to remove heavy metals from aqueous solutions. In this investigation, sepiolite mineral was obtained from a mine near Fariman Township, Khorasan, Iran. The mineral samples used in this study were powdered with sizes less than ۰.۰۵ mm (-۱). Langmuir and Freundlich isotherm models were investigated to illustrate the adsorption of heavy metals by natural and heat pre-treated sepiolites from aqueous solutions in two different pH values: ۴ and ۵. It was determined that the experimental data were more fitted to the Langmuir model (R۲≈۰.۹۹) and it was observed that cobalt ions were more adsorbed than zinc and cadmium in the order of adsorbing regularity: Co>Zn>Cd. In this study, the quantities of released Mg۲+ from the mineral structures were also investigated. In addition, changes in pH values in final solutions were investigated at the end of the experiments.

heavy metals, Environmental pollutions, Sepiolite, Langmuir and Freundlich