Adsorption Isotherms for Removal of Heavy Metal Ions (Copper and Nickel) from Aqueous Solutions in Single and Binary Adsorption Processes

Abstract

This study deals with the removal of single and binary heavy metals, which cause great problems in terms of the environment and human health, through very low cost, economical and easily obtainable materials. The purpose of this study is to investigate the single- and binary uptake of Copper (II) and Nickel (II) ions onto the Sepiolite in the terms of a thermodynamic perspective. For mono-component systems, the initial effluent concentration, mixing speed and temperature have been studied as a function of time to determine the conditions where the adsorbents show a great deal of affinity towards the Cu (II) and Ni (II) ions in aqueous solutions. Before the metal adsorption experiments, the Physical properties of Sepiolite were identified via Brunauer–Emmett–Teller (BET) analysis. The single metal ion uptake studies were performed at 20, 25, 30, and 35 °C. At equilibrium, the sorption data were individually shown to correlate well with the non-competitive Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms. Among the applied isotherm models, the one-component sorption values do fit the Langmuir isotherm best. The simultaneous and competitive uptake of Cu (II) and Ni (II) was assessed by the extended Langmuir and Freundlich isotherms. Both adsorption equations complied with the two-component sorption data perfectly. Single- and binary-sorption results unclose that the effect of Sepiolite to Cu (II) is greater than that of Sepiolite to Ni (II).