Funtionalized Sol−Gels for Selective Copper(II) Separation

Inorganic−organic hybrid SiO 2 sol−gels anchored with amino (NH 2 −CH 2 CH 2 −NH-, TMSen, and −NH−CH 2 CH 2 −NH-, Bis-TMSen) and mercapto (HS-) ligands have been studied as new sorbents for Cu 2+ separation. The TMSen-anchored gels were found to be selective for Cu 2+ removal in the presence of Cd 2+ and Zn 2+ . In comparison, mercapto-anchored gels remove both Cu 2+ and Cd 2+ from a mixture of Cu 2+, Cd 2+, and Zn 2+ . These ligand-anchored materials, which were easily prepared from off-the-shelf chemicals in ca. 1 h, were hydrophilic and thus may give potentially fast kinetics of metal upload and removal (from the gels) in aqueous solutions. The ligand-anchored sol gels loaded with Cu 2+ ions were regenerated with acid, and the materials could then be used in subsequent metal removal cycles. The effect of the reaction conditions [catalysts, ligand/Si(OMe) 4 ratios, and curing temperatures] on sol−gel properties and performance were investigated. In addition, the kinetics of Cu 2+ upload and removal by these ligand-anchored sol−gel materials were studied. The work here shows that these hydrophilic ligand-anchored sol−gels are a good alternative to ligand-anchored organic polymers for toxic metal separation.