KINETICS AND THERMODYNAMIC STUDIES ON REMOVAL OF CADMIUM METAL ION FROM AQUEOUS SOLUTION USING RICE STRAW

The removal of Cd(II) from aqueous solution by batch adsorption technique using rice straw (SIII) and its ash (R400), in absence and presence of 0.005M hydrochloric acid were used to determine the adsorption efficiency. Kinetic studies were performed to understand the mechanistic steps of the adsorption process and the rate kinetics for the adsorption of Cd(II). The kinetic data supports pseudo-second order model and intra-particle model but shows very poor fit for pseudo-first order model. Thermodynamic parameters including the Gibbs free energy, enthalpy, and entropy indicated that the adsorption of Cd(II) ions was feasible, spontaneous in absence of HCl and exothermic in all media under studying, at temperature range of 25–45 C.