Dipicolinamide functionalized titania for highly efficient sorption of tetra and hexavalent actinide

Abstract

Dipicolinamide functionalized titania particles have been synthesized for efficient decontamination of uranyl and thorium ions from aqueous acidic waste solution. Langmuir isotherm was found to be predominating with maximum sorption capacity of 125 mg/g for Th and 111 mg/g for U, respectively. The sorption was found to follow pseudo 2nd order kinetics predominately, with rate constant 8.6E−04 mg g−1 min−1 for Th and 6.1E−04 mg g−1 min−1 for U, respectively. Up to 200 kGy of gamma irradiation, not much deterioration in extraction performance of sorbent material was observed. Three contacts of 0.1 M aqueous solutions of oxalic acid and sodium carbonate were found to be effective in quantitative elution of Th4+ and UO22+ from the loaded sorbent, respectively. The sorption of U and Th on dipicolinamide functionalized titania was evidenced by SEM images, elemental mapping and the EDX. Theoretical investigation revealed that, the solution phase free energy of sorption (ΔGsol) was higher for Th4+ (−114.1 kcal mol−1) compared to UO22+ (−80.41 kcal mol−1).