Investigation of Copper Removal from Aqueous Solution by Cement Kiln Dust as Industrial By-Product

This study investigated the copper (Cu^+2) removal from aqueous solution by cement kiln dust (CKD) as industrial by-product in cement manufacturing process. CKD was identified by Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and surface areas show the differences of physicochemical properties. Batch equilibrium experiments were carried out at 20, 25 and 30^ oC with time intervals extended to 96 h to investigate the efficiency of the CKD in the removal of Cu^+2. CKDexpressed high affinity for removal of Cu^+2 and was not affected by temperature or time. The removal of Cu^+2 was indicated by changes of FTIR and SEM images before and after sorption experiments. The kinetic data were evaluated by fractional power, Elovich, pseudo-first order and pseudo-second-order kinetic models. The kinetic studies demonstrated that rate of the removal followed pseudo-second-order kinetic model (r^2=0.99). Thermodynamic parameters, the change of free energy (ΔG◦), enthalpy (ΔH◦) and entropy (ΔS◦) were calculated for predicting the nature of adsorption. The parameters showed that the process was feasible, spontaneous and exothermic under experiment conditions. Solubility equilibrium for various expected copper compounds was estimated and the solubility of copper in Cu-CKD system suggested to be controlled by Cu CO-3 precipitation under experiment condition. The results indicated that CKD can be used as a low cost and effective sorbent for copper ions from aqueous solutions.