Adsorption and thermodynamic behaviour of U(VI) on the Tendurek volcanic tuff

In this work, sorption of uranium ions on volcanic tuff collected from the deposits located at the Tendurek of Eastern Turkey was investigated in batch technique. The effect of different parameters such as pH of the medium, contact time, uranium concentration and temperature were investigated. The maximum removal of U(VI) was found to be 68% at pH 5.0, initial U(VI) con- centration of 75 mg L -1 and 30 C. Thermodynamic parameters, such as enthalpy of adsorption DH, free energy change DG and entropy change DS have been also calculated and interpreted. The suitability of the Langmuir, Freundlich and Dubinin-Radushkhevic adsorption models to the equilibrium data was investigated for uranium-vol- canic tuff system. The results suggest that volcanic tuff can be used as efficient and cost effective adsorbents for uranium ion removal.