Comparative and competitive adsorption of Cu(II) and Cd(II) using scoria: Equilibrium, kinetic and thermodynamic studies

Abstract

Heavy metals such as Cu(II) and Cd(II) are among the hazardous pollutants that lead to severe ecological problems and have a toxic effect on living organisms. This study was carried out on adsorption of Cu(II) and Cd(II) from single- and multi-component aqueous solutions with Iranian scoria. Two- and three-parameter isotherm models such as Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Khan and Toth have been studied for single and binary adsorption of Cu(II) and Cd(II) onto scoria. The best result was attained from Langmuir model for Cu(II) and Cd(II) ions in single and binary solution. Therefore, homogenous adsorption is dominated which was emphasized by three-parameter isotherm models. Based on the value of the free energy of adsorption for Cu(II) and Cd(II), the interaction between these ions and scoria is a physical adsorption. In order to investigate competitive adsorption behavior, modified and extended Langmuir and Freundlich models have been studied which indicated that adsorption of Cu(II) and Cd(II) on scoria has synergistic behavior. Extended Freundlich model and modified Langmuir model described Cu(II) and Cd(II) adsorption onto scoria, respectively.