Boichenko I. Sorption processes of noble metals on silica gel, activated by N-(5-mercapto-1,3,4-thiadiazol-2-yl)-N’-propylurea groups

The thesis is devoted to the experimental research of sorption processes of noble metal ions on silica gel surface chemically modified with N-(5-mercapto-1,3,4-thiadiazol-2-yl)-N’-propylurea groups (MTS). The complexing properties of grafted ligand in homogeneous media was not investigated because of its insolubility in aqueous and non-aqueous solvents. It is supposed that sorption on the MTS may occur via complexation and/or anion-exchange mechanisms depending on pH and acidity of solutions on the basis of MTS sorption properties, spectroscopic characteristics of metals sorbates and quantum-chemical calculation of the grafted molecule electronic structure. Quantitative sorption of Pd(II), Au(III), Ag(I), Pt(II), Ru(III) occurs on the MTS over a wide range of solution acidity, whereas non-ferrous metal ions are not sorbed from solutions with pH values less than unity. The composition of surface complexes of noble metals on the MTS was established using methods of IR-, diffuse reflection spectroscopy and low-temperature luminescence.