Extraction chromatographic materials based on polysulfone microcapsules for the sorption of strontium from aqueous solution

Abstract

Crown ether-loaded polysulfone (PS) capsules suitable for the separation and preconcentration of strontium from acidic nitrate media have been prepared and characterized. Specifically, PS macro- and microcapsules have been impregnated with the macrocyclic polyether di-tert-butylcyclohexano-18-crown-6 (DtBuCH18C6), either undiluted or as a solution in 1-octanol, and their performance in the extraction of strontium from nitric acid solution evaluated. The DtBuCH18C6-loaded microcapsules were found to exhibit strontium uptake efficiency significantly greater than that observed for the analogous macrocapsules, confirming earlier observations of a marked size-dependence of the behavior of extractant-loaded PS capsules. Comparison of the microcapsules to a commercial extraction chromatographic (EXC) material (Sr-resin) comprising DtBuCH18C6-loaded beads of poly(methyl methacrylate) (PMMA) of comparable size (50–100 μm), showed that the two materials exhibit similar strontium retention, uptake kinetics, and selectivity. The microcapsules provide higher column efficiencies, however, and when fully loaded with extractant, higher strontium ion uptake capacity.