Syntheses of polyamine-bridged polysilsesquioxanes hybrid materials combining sol-gel processing and molecular imprinting applied to selective adsorption for copper

Bridged polysilsesquioxanes hybrid materials with Cu(II) recognition properties were synthesized by sol-gel method and imprinting techniques in this paper. Polyamine-bridged monomers containing soft long-chain organic bridge were used to synthesize these materials possessing high ligand densities and good selectivity for Cu(II). Three classes of Cu(II) imprinted materials were synthesized according to the following routes: (1) self-condensation of polyamine-bridged monomers, (2) co-condensation of tetraethoxysilane (TEOS) and polyamine-bridged monomer around supramolecular assemblies of hexadecyltrimethylammonium bromide (CTAB), and (3) co-condensation of TEOS, 3-aminopropyltriethoxysilane (APES) and polyamine-bridged monomers around CTAB. Adsorption tests showed that materials obtained with the addition of TEOS and CTAB exhibit an enhanced capacity as compared to the nonimprinted material for the adsorption of Cu(II). The addition of APES increased the content of functional groups and then improved the adsorption capability. Selective adsorption tests showed that materials had better selectivity for Cu(II) in the mixtures of Cu(II)-Ni(II), Cu(II)-Pb(II), Cu(II)-Cd(II) and Cu(II)-Zn(II), but poorer selectivity in Cu(II)-Hg(II) and Cu(II)-Ag(I) mixtures.