Thorium adsorption from waste effluents by phosphate-enhanced chitin

Abstract

Phosphate-grafted chitin (PGC) was synthesized for thorium adsorption from acid solutions. FTIR analysis shows that the phosphate and amide groups of PGC are involved in the adsorption. The Th(IV) adsorption is pH-dependent and is maximal at pH 3.5. The adsorption kinetics is described by a pseudo-second-order kinetic model. The maximum monolayer adsorption capacity obtained from the Langmuir model is 50.5 mg Th(IV)/g at 25°C. Thermodynamic analysis shows that the adsorption is spontaneous and exothermic. The phosphate-grafted chitin can be reused by activating its surface with 0.5 M HCl–0.1 M EDTA.