title: Crown ether-doped sol-gel materials for strontium(II) separation
abstract: 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-7,16-diazacyclooctadecane-7,16-bis(malonate) ligand (Na4oddm), with known high affinity for Sr2+ was encapsulated in hydrophilic SiO2 through a simple sol-gel process. Washing the Sr(2+)-loaded gel 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 extraction or the use of sorbents containing chemically grafted crown ether ligands.
authors.initials: TL
authors.lastname: Yost
authors.initials: BC
authors.lastname: Fagan
authors.initials: LR
authors.lastname: Allain
authors.initials: CE
authors.lastname: Barnes
authors.initials: S
authors.lastname: Dai
authors.initials: MJ
authors.lastname: Sepaniak
authors.initials: Z
authors.lastname: Xue