Self-organized inorganic-organic phyllosilicate hybrids: investigating bridging ligands and imprinting methods for heavy metal ion adsorption

Abstract

The talc-like organoclay, MgSi-b-en, was synthesized using a bridged organosilane precursor containing the ethylenediamine moiety through the sol-gel process. Characterization of the material revealed disordered, interconnected phyllosilicate sheets, with a high surface area and a composition resembling natural talc. Ethylenediamine moieties were successfully incorporated into the structure of MgSi-b-en. The material performed well as an adsorbent of the heavy metal ions Cu(II), Ni(II), and Pb(II). The adsorption capacities of the adsorbent were very high. Multi-component adsorption tests revealed a specific adsorption preference of Pb > Cu > Ni. An ionimprinting technique was performed to alter the specificity of the adsorbent. The procedure produced organoclays with cavities matching the size of the metal ion used in the synthesis. In the presence of larger ions, the two imprinted adsorbents, MgSi-b-en(- Cu) and MgSi-b-en(-Ni), displayed higher adsorption capacities and selectivity coefficients towards Cu(II) and Ni(II) ions, respectively.