Study on Th(IV) Adsorption Properties on Natural and Surface-Modified Red Soil

Abstract

In order to study the effects of inorganic and organic modification on the adsorption properties of red soil (RS), ferric chloride (FC) and hexadecyl trimethyl ammonium bromide (HTAB) surface-modified red soil have been prepared and characterized by SEM, FT-IR and X-ray diffraction. Adsorption properties of Th(IV) on natural red soil (NRS), FC surface-modified red soil (FC-RS), and HTAB surface-modified red soil (HTAB-RS) have been investigated by batch technique. The inorganic and organic modification have been found to greatly improve the adsorption kinetics and thermodynamic properties and increase the adsorption capacity as compared with NRS. The adsorption of Th(IV) on the three adsorbents have been strongly dependent on pH and ionic strength, and intra-particle diffusion was the rate-controlling step. The non-linear pseudo-second-order kinetic model could fit the kinetics much better compared with the linear forms, and the linear and non-linear Langmuir expressions could fit the thermodynamics. The results obtained denote on successful application of inorganic and organic modification to treatment of water samples spiked to Th(IV) ions.