Bifunctional Phosphinic Acid Resins for the Complexation of Lanthanides and Actinides

Abstract

Phosphinic acid ion exchange/redox resins are synthesized by the reaction between polystyrene beads and phosphorus trichloride followed by base hydrolysis. The reaction requires a temperature of 73°C for full functionalization to occur. The effect of lower functionalization temperatures on resin acid capacity was determined and the concomitant effect on ion exchange investigated. The acid capacity was found to vary from 1.68 mequiv/g to 4.79 mequiv/g in the functionalization temperature range studied (15°C to 73°C). The percent resin sites loaded with zinc ions is independent of the actual capacity. The extracting ability of the phosphinic acid resin for europium, thorium, uranium, americium, and plutontutn was examined as a function of acid concentration from acid nitrate solutions both at varying and constant ionic strength. The phosphinic resins show better extraction for these ions than the sulfonic resins, especially from high acid solution (4M HNO₃) due to the superior coordination ability of the phosphoryl oxygen. They also show a higher selectivity for the ions tested over sodium. For example, under conditions where sulfonic resins absorb 85% of the plutonium in solution, the phosphinic acid resins absorb 99.7%.