Electrochemical evaluation of polysiloxane-immobilized amine ligands for the accumulation of copper(II) species
Résumé
Accumulation of copper(II) by amine ligands immobilized by covalent binding to silica-based materials was examined by electrochemistry at modified carbon paste electrodes. Three samples were compared: a silica gel grafted with aminopropyle groups, an organic–inorganic hybrid resulting from the condensation of tetra-ethoxysilane and aminopropyle-triethoxysilane and a mesoporous pure silica MCM-41 material grafted with aminopropyle groups. These solids were characterized by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, acid–base titration, N2 adsorption and for their ability to accumulate copper(II) species. Electrochemical detection was achieved after accumulation of copper(II) at open circuit and both preconcentration and detection steps were optimized by varying pH, preconcentration time and the composition of the detection medium. Results are discussed with respect to the nature of the modified silicas.