| Abstract
| - Inorganic−organic hybrid SiO2 sol−gels anchored withamino (NH2−CH2CH2−NH-, TMSen, and −NH−CH2CH2−NH-, Bis-TMSen) and mercapto (HS-) ligands have beenstudied as new sorbents for Cu2+ separation. The TMSen-anchored gels were found to be selective for Cu2+removal in the presence of Cd2+ and Zn2+. In comparison,mercapto-anchored gels remove both Cu2+ and Cd2+from a mixture of Cu2+, Cd2+, and Zn2+. These ligand-anchored materials, which were easily prepared from off-the-shelf chemicals in ca. 1 h, were hydrophilic andthus may give potentially fast kinetics of metal uploadand removal (from the gels) in aqueous solutions. The ligand-anchored sol gels loaded with Cu2+ ions were regeneratedwith acid, and the materials could then be used insubsequent metal removal cycles. The effect of the reactionconditions [catalysts, ligand/Si(OMe)4 ratios, and curingtemperatures] on sol−gel properties and performance wereinvestigated. In addition, the kinetics of Cu2+ upload andremoval by these ligand-anchored sol−gel materials werestudied. The work here shows that these hydrophilic ligand-anchored sol−gels are a good alternative to ligand-anchoredorganic polymers for toxic metal separation.
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