STRONTIUM EXTRACTION WITH A POLYMER-BOUND 18-CROWN-6 POLYETHER

A 18-C-6 crown ether-functionalized polystyrene network (2.04 mmol 18- C-6/g, noted R-18C6) has been synthesized by reaction of hydroxymethyl -18-crown-6 with the related chloromethylated polymer (5.6 mmol Cl/g, 6.5% crosslinked with divinylbenzene). The extraction of strontium fro m 1 M LiNO3-LiCl aqueous solutions with R-18C6 has been studied. The e xperimental data agree with the sorption equilibrium Sr2+ + 2NO3- + 1 8C6 half arrow right over half arrow left 18C6,Sr(NO3)2 (log K25-degr ees-C = 2.52, and the superscript asterisk denotes a polymer bound spe cies). Sr(NO3)2 is selectively extracted with R-18C6 from aqueous nitr ate solutions containing trivalent lanthanum and europium. Replacing L iNO3 with HNO3 does not alter the extraction yield. The stripping of S r(NO3)2 from the polymer network is complete at 60-degrees-C in distil led water but, owing to poor water swelling of the resin. the kinetics of extraction and stripping are rather slow.