Assessment of Cyanex 301 impregnated resin for its potential use to remove cobalt from aqueous solutions

Abstract

The feasibility of using Cyanex 301 impregnated onto biopolymer resin for removing cobalt from radioactive waste streams is investigated. The emulsion compositions for resin preparation were optimized to ensure compliance with nuclear grade resin specifications on particle size distribution and chemical stabilities using multi-variant analysis. The enhanced chemical stabilities of the resins in different solutions are attributed to the interaction between Cyanex 301 and the emulsifier with alginate via a reaction with the glycosidic bond. The structure and morphology of the three optimized samples were studied using FTIR, SEM, and TGA and their end-of-life cycle treatment was preliminarily investigated. Equilibrium sorption investigations revealed that the sorption is taking place via bi-layers onto two sites on the surface layer independently from the cobalt contamination level and the nature of these sites were characterized by determining the energy barriers and fraction of the weak and strong sites. Cobalt adsorption is chemical spontaneous endothermic reaction and the loaded material spectroscopic analysis and thermodynamics calculations referred to chemical coordination and hydrogen bonding. The enhanced radiological stabilities of the optimum resins at irradiation fields <100 KGy were explained and the relations between the loss of exchange capacity and the doses were quantified. The resins could be regenerated using 0.5 M HCl and the effect of the elution cycles on cobalt uptake was presented.