Selective extraction of strontium with supercritical fluid carbon dioxide
Abstract
Strontium (Sr2+) can be selectively extracted from aqueous solutions into supercritical fluid CO2 at 60 °C and 100 atm with dicyclohexano-18-crown-6 (DC18C6) using CF3(CF2)6CO2– (PFOA–) or CF3(CF2)6CF2SO3– (PFOSA–) as a counter anion; at a mole ratio of Sr2+ : DC18C6 : PFOA– = 1:10:50, the extraction of Sr (5.6 × 10–5 M) from water at pH 3 is near quantitative whereas Ca2+ and Mg2+ at equal concentration are only extracted to a level of 7 and 1%, respectively; PFOSA– is an effective counter anion for selective extraction of Sr2+ from 1.3 M HNO3 with DC18C6 in supercritical CO2.