Synthesis and characterization of novel silica gel supported N-pyrazole ligand for selective elimination of Hg(II)

The polar organic molecule N-(2-hydroxyethyl)-3,5-dimethylpyrazole reacted with a 3-glycidoxypropyltrimethoxysilane silylant agent, previously anchored on a silica surface in a heterogeneous way to yield the product SiPz. The epoxide group was opened yielding chelating pendant group bonded to the inorganic surface. The product was characterized through elemental analysis, infrared spectroscopy, 13C NMR, surface area and thermogravimetry. The binding and adsorption abilities of SiPz was investigated for Hg2+, Cd2+, Pb2+, Cu2+, Zn2+, K+, Na+ and Li+ cations and compared to results of classical liquid–liquid extraction with the unbound N-pyrazole compound. The grafting at the surface of silica does not affect complexing properties of the ligand and the SiPz exhibits a high selectivity toward Hg2+ ion with no complexation being observed towards Zinc and alkali metals. The extracted and the complexing cation percentage were determined by atomic absorption measurements.