Research Article
P Thilagavathy ,T Santhi, S Ma
Abstract
The applicability of Acacia nilotica as adsorbent for the effective removal of Co(II) from aqueous solutions was investigated. Batch experiments were performed to study the effects of various parameters such as pH, initial concentration, biosorbent dose and contact time was studied for adsorption of Co(II) ion. Kinetics and isotherm models were validated to understand the mechanism of adsorption of Co(II) ion by AN. Thermodynamic properties such as ΔG˚, ΔH˚ and ΔS˚ were determined for the cobalt adsorption. Further, the adsorption of cobalt ion was confirmed through instrumental analyses such as SEM and FTIR. Maximum adsorption was observed at the pH range of 5 with an initial concentration of 50 mg/L of the adsorbate. The percentage adsorptions were found to be 81%. Results indicated that adsorption process obeys Freundlich isotherm model other than other models. The pseudo-first order and pseudo- second order kinetic equations were used to model the adsorption kinetics, with the pseudo second order giving a better fit, as seen from the correlation coefficient (R2 ) which is 0.9897 for pseudo-second order model. The applicability of the Elovich equation and intra particle diffusion model to the sorption kinetics were also investigated. negative enthalpy confirmed that the process was exothermic. The desorption and recyling ability of Co(II) and AN are found to be good. This work therefore shows that Acacia nilotica leaf could be used to remove Co(II) ions from aqueous solutions.