Removal of U(VI) and Th(IV) from aqueous solutions by organically modified diatomaceous earth: Evaluation of equilibrium, kinetic and thermodynamic data

Raw and organically modified diatomaceous earth were used to remove U(VI) and Th(IV) ions from aqueous solution using the batch method. Effects of contact times, dosage of adsorbent, pH, ionic strength and temperature on the adsorption process were studied. The results indicated that the adsorption of these ions was affected by pH and ionic strength. The adsorption isotherms fit the Langmuir, Freundlich and D-R models at different temperature. The kinetic results revealed that pseudo-second-order kinetic model provided the best description of the equilibrium data. Thermodynamic parameters showed the adsorption process was spontaneous and endothermic. The best recovery for U(VI) was obtained when 1.0 M EDTA was used as eluent, while for Th(IV) ions when 1.0 M HNO3 was used. (C) 2017 Elsevier B.V. All rights reserved.