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.

Rational Synthesis of Imprinted Organofunctional Sol-Gel Materials for Toxic Metal Separation - Final Report - 09/15/1997 - 09/14/2001

“…Microporous metal oxides such as silica, titania, zirconia and mixed oxides MNO 2 -SiO 2 (MN = Ti, Zr) readily adsorb uranyl ions via ion exchange reactions with surface silanols. 9 Little is known, however, about the adsorption properties of mesoporous analogues of these oxides. We have prepared a series of surfactant ordered, mesoporous mixed TiO 2 -SiO 2 oxide (100% 6 0% Si vs. Ti) materials and studied the binding affinities they exhibit toward buffered solutions (CH 3 COOH/CH 3 COONa; pH ~ 5) of the UO 2…”

Selective hydrogenation of Dibenzo-18-crown-6 ether over highly active monodisperse Ru/γ-Al2O3 nanocatalyst

“…Crown ethers, a class of macrocyclic ligands, are found to be effective solvent as they possessed high affinity and selectivity for alkali and alkaline earth metal ions [3]. The selectivity in complexation of crown ether with a particular cation depends on the size of the ring and its stereochemistry.…”

Optical and electrochemical sol-gel sensors for inorganic species

“…Factors such as the size of the alkoxide ligand, solution pH, organic substitutions (for one or more of the alkoxide groups), solvents, temperature, and catalyst selection can all be adjusted to give different products [1][2][3][4][5][6][7][8][9] . As a result, sol-gels have been used in many applications including electronics, optics, separations, catalysis, and sensing [1,[10][11][12] .…”