Thermodynamic Characterization of Sorption of Copper(II) ions on Rice Husk

This paper attempts to develop simple and easily understandable thermodynamic parameters related sorption process at the equilibrium. Batch kinetic studies were conducted for the adsorption of Cu(II) on SCRH (sodium carbonate treated rice husk). The removal were observed to increases from 92.9 to 96 % with the increase in temperature from 15° to 50° C. Equilibrium time was found to be 60 min. The overall scenario represented by thermodynamic parameters was found to be a better indicator of understanding the process mechanism. Sorption of Cu(II) on SCRH followed pseudo second-order kinetic equation. The Gibbs free energy ΔG° values for the adsorption processes of Cu(II) at 15° , 30° , 40° and 50 °C was obtained as ? 6.16, ? 6.84, ? 8.01 and ? 8.53 kJ/mol respectively. The negative value, ΔG° confirms the feasibility of the adsorption process and spontaneous nature of adsorption. The values of ΔH° and ΔS ° for Cu(II) were obtained as 14.37 kJ/mol and 70.92 J/mol respectively. The positive value of ΔH° indicates endothermic nature of adsorption, while positive ΔS ° value confirms the increased randomness at the solid-liquid interface during adsorption. The activation energy for the sorption of Cu(II) was found as 9.00 kJ/mol indicating chemisorptions.