Abstract

Batch kinetic studies were conducted for the adsorption of Cd(II) on NCRH. At the adsorbent dose of 10 g/land initial Cd(II) concentration of 10 mg/l, 93 to 97 % removal were observed when the temperature increases from 15 o to 40o. Equilibrium time was found to be 60 min. This paper attempts to develop simple and easily understandable thermodynamic parameters related sorption process at the equilibrium. The overall scenario represented by thermodynamic parameters was found to be a better indicator of understanding the process mechanism. Sorption of Cd(II) on NCRH followed pseudo second-order kinetic equation. The standard Gibbs free energy ΔGo value for the adsorption processes of Cd(II) was obtained as – 7.30 kJ/mole. The negative value, ΔGo confirms the feasibility of the adsorption process and spontaneous nature of adsorption. The values of ΔHo and ΔSo for Cd(II) were obtained as 26.4, kJ/mol and 113.2 J/mol respectively. The positive value of ΔHo indicates endothermic nature of adsorption, while positive ΔSo value confirms the increased randomness at the solid-liquid interface during adsorption. The activation energy for the sorption of Cd (II), was found as11.37 kJ/mol indicating chemisorption.