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

Abstract

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 K-D versus 1/T. The DeltaHdegrees and DeltaGdegrees values of uranium(VI) adsorption on amberlite IR-118H show endothermic heat of adsorption; higher temperatures favor the process. (C) 2003 Elsevier Science Ltd. All rights reserved.