Thermodynamic and kinetic investigations of uranium adsorption on amberlite IR-118H resin

The adsorption behavior of uranium(VI) on a strongly acidic cation exchanger amberlite IR-118H has been studied as a function of the solution concentration and temperature. Results have been analyzed by Langmuir and Dubinin–Radushkevich (D–R) adsorption isotherms. The mean energy of adsorption 7.14 kJ mol−1 was calculated from the D–R adsorption isotherm. In order to understand the significance of the diffusion mechanisms and to accurately estimate the diffusivities inside the adsorbent particles, a model for uranium(VI) adsorption on amberlite IR-118H was used. The rate constants have been calculated for 293, 313 and 333 K using Lagergren equation and the activation energy (Ea) was derived using the Arhenius equation. The thermodynamic quantities for the process of adsorption have been estimated by plotting Ln KD versus 1/T. The ΔH° and ΔG° values of uranium(VI) adsorption on amberlite IR-118H show endothermic heat of adsorption; higher temperatures favor the process.