Adsorption characteristics of natural zeolite towards Th(IV) and Eu(III) ions

In this communication we report the adsorption properties of clinoptilolite (a type of natural zeolites inSabzevar region) towards Th(IV) and Eu(III) ions from aqueous solution. The effect of parameters affecting theadsorption process like aqueous solution pH, contact time, mass of adsorbent, initial concentration of metal ions andtemperature are studied and discussed. The adsorption efficiencies of the sorbent were found to be pH dependent. Themaximum adsorption of thorium and europium ions was obtained at pHs 3.5 and 5, respectively. It is found that underoptimum conditions i.e. pH=3.5, 20 min. by 0.04 g of the adsorbent, for thorium ions, and pH=5, 45 min., 0.1 g of theadsorbent for europium ions, the metal ions can be quantitatively removed from 20 mL aqueous solutions containing 20mg L-1 of metal ions. Selective separation of these ions can be achieved by controlling the aqueous phase pH.