Ion Exchange Behavior of Zeolites A and P Synthesized Using Natural Clinoptilolite

The main goal of this study is to investigate the capability of zeolites A and P synthesized from Iranian natural clinoptilolite for uranium uptak. The removal of uranium(VI) from aqueous solution via ion exchange by zeolites in a single component system with various contact times, temperatures and initial concentrations of uranium(VI) was investigated. The experimental results were fitted to the Langmuir and Dubinin-Radushkevich isotherms to obtain the characteristic parameters of each model. Both the Langmuir and Dubinin-Radushkevich isotherms were found to good represent the measured adsorption data. Using the thermodynamic equilibrium constants obtained at two different temperatures, various thermodynamic parameters, such as ΔG˚, ΔH˚, and ΔShave been calculated. The thermodynamics of uranium(VI) ion and zeolite system indicates the spontaneous and endothermic nature of the process. It was noted that an increase in temperature resulted in a higher uranium loading per unit weight of the adsorbent.