Removal of thorium(IV) from aqueous solutions by natural sepiolite

Natural sepiolite has been tested as a potential sorbent for the removal of Th(IV) from aqueous solutions by batch technique. Effects of various parameters on the adsorption process have been investigated. Under optimum conditions, Th(IV) was adsorbed with high adsorption efficiency. The results indicated that sorption of Th(IV) on sepiolite was strongly affected by pH values and temperature. The adsorption patterns of thorium on the sepiolite adsorbent followed the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The thermodynamic data(Delta H degrees, Delta S degrees, Delta G degrees) are calculated from the temperature-dependent sorption isotherms. The results suggest that sorption process of Th(IV) on sepiolite is spontaneous and endothermic.