ABSTRACT
The effect of temperature on the adsorption of heavy metals on not only natural bulk clay, but also for the individual phases that composed the bulk clay sample, was investigated. Combined Adsorption-Sequential extraction Analysis [CASA] for Pb, Cu, Zn and Cd were conducted under various temperatures that ranged from 15 [degree sign] C to 55 [degree sign] C. The effect of temperature on the individual phases was mainly observed in oxide, including Fe-and Mn-oxide, and the organic phases of all of the meals. As for the Phase Concentration Factors [PCFs] of the metals, the largest increase of the values was observed in the oxide phase. Based on the thermodynamic parameters of the individual phases, the adsorption of metals on natural clay was an endothermic reaction with the exception of exchangeable phase adsorption. This shows that adsorption affinity and capacity tend to increase when the temperature increase for all adsorption phases of soil, except for adsorption in the exchangeable phase. In the case of Pb, Zn, and Cu adsorption, the considerable enthalpy changes were observed in carbonates, Fe-oxides, and organic phases, which means the small enthalpy changes in the Cd adsorption were observed in bulk and all individual phases when it was compared with the other metals enthalpy changes for the same phases. This means that Cd adsorption mainly occurred in the exchangeable phase, which was affected a little by temperature change