Adsorptive uptake Th(IV) by red soil and black soil

Abstract

Adsorption of Th(IV) on red soil and black soil was studied as a function of ionic strength, pH, solid–liquid ratio, contact time, temperature and initial concentration through batch static tests, and the soils were characterized by SEM, XRD and IR. The results showed that the adsorption reaction was rapidly and greatly affected by pH. The experimental data conformed to the Freudlich model and the pseudo-second-order kinetic model, reflecting nonlinear chemical adsorption. Furthermore, the intra-particle and liquid film diffusion occurred simultaneously during the Th(IV) adsorption on the soils, and adsorption reaction was controlled by cation exchange reactions. According to adsorption thermodynamics in this experiment, the adsorption of Th(IV) on these two soils was found to be a spontaneous and endothermic process. Both soils were good adsorbents; however, the adsorption rate of black soil was faster, and its adsorption capacity was larger.