Complex formation of ruthenium(IV) and osmium(VIII) with 1,10-phenanthroline on the surface of silica sorbents

Abstract

A study was made of the sorption of ruthenium(IV) and osmium(VIII) by silica and silica with chemically grafted sulpho groups from solutions containing 1,10-phenanthroline. Using diffuse reflection, luminescence and x-ray photoelectron spectroscopic methods, it was found that during sorption at pH 6–7 and room temperature on the surface of silica sorbents phenanthrolinate complexes of various composition are formed, bis- and tris(1,10-phenanthroline)metal (II, III), the Os(II) to Os(III) mole ratio being 2:1. A quantitative yield of tris(1,10-phenanthroline)metal(II) complex is obtained at 98 /+- 2 °C. The rate of complex formation on the surface of the sorbents considerably exceeds the rate of formation of the corresponding complexes in solution. It is suggested that silica sorbents have a catalytic action on the process of formation of complexes of ruthenium and osmium with 1,10-phenanthroline on the sorbent surface. A rapid sorption-luminescence method for determining ruthenium and osmium is proposed. The detection limit is 7 × 10 −4 μg ml −1 for ruthenium and 1 × 10 −3 μg ml −1 for osmium.