Crown ether-doped sol-gel materials for strontium(II) separation

Hybrid organic/inorganic sol-gel materials containing an encapsulated crown ether ligand were found to selectively remove 91.4 +/- 1.3% of Sr2+ from a solution containing excess of competing ions such as Ca2+. The crown ether ligand, 1,4,10,13-tetraoxa-7,1 6-diazacyclooctadecane-7, 16-bis(malonate) ligand (Na(4)oddm), with known high affinity for Sr2+ was encapsulated in h ydrophilic SiO2 through a simple sol-gel process. Washing the Sr2+-loaded g el with acid or ethylenediaminetetraacetic acid disodium salt recovered the Sr2+ from the sol-gel sorbent and regenerated the doped gel for subsequent Sr2+ intake. The approach reported here is a new alternative to the use of crown ethers in metal ion separation through, for example, solvent extract ion or the use of sorbents containing chemically grafted crown ether ligand s.