Adsorption of Copper and Cadmium with Perlite and Comparison of Adsorption Properties

This study, the effectiveness of perlite for the removal of Cu (II) and Cd (II) ions from aqueous medium was investigated by adsorption method. Using perlite adsorbent, parameters such as initial concentration, initial pH, adsorbent dosage and contact time affecting Cu (II) and Cd (II) ions adsorption from aqueous solutions were investigated. Initial concentration of copper (II) ions, initial pH value, adsorbent amount, contact time respectively 3.2 ppm, natural pH 6.49, 2 g, during the 180 minutes adsorption 94% of copper ions adsorbed, the initial concentration of cadmium (II) ions solution, initial pH, adsorbent amount, contact time 5.6 (ppm), natural pH 5.25, 2 g, 180 minutes, respectively, 77% adsorbed. It was determined that the adsorption data fit the Langmuir isotherm for copper ions and Freundlich isotherm for cadmium ions, and the kinetic data of copper and cadmium ions fit the false second order model. Including the thermodynamic parameters of adsorption, Gibbs free energy change (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) values calculated at 20oC are for copper 3.1 kJ mol-1, -55.52 kJ mol-1, -0.2 kJ mol-1 K-1 , respectively and for cadmium, 7.14 kJ mol-1, -28.02 kJ mol-1, -0.12 kJ mol-1 K-1, respectively. The results showed that the adsorption of these metal ions on the perlite is exothermic and feasible at 20-50°C.