Application of Silica Chemically Modified by Sulfur-Containing Groups to the Separation and Determination of Platinum and Rhenium in Catalysts Based on Aluminum Oxide

Abstract

⎯Adsorbents based on silica chemically modified by sulfur-containing groups (dithiocarbamate, thiodiazolethiol, mercaptophenyl, and aminobenzothiazole) quantitatively extract (recovery ≥99%) platinum(IV) from solutions ranging from 4 M HCl to pH 6. Under the conditions of the adsorption separation of platinum(IV), rhenium(VII) is not extracted and remains in the solution. The subsequent quantitative (98-99%) adsorption of rhenium(VII) is achieved in the presence of a 1000-fold excess of tin(II) chloride. Adsorption on the surface of adsorbents leads to the formation of platinum(II) complexes with sulfur-containing groups, luminescent at 77 K on irradiation with UV light. The luminescence spectra of surface platinum(II) complexes are located in the region of 550-700 nm. In the adsorption of rhenium(III) in the presence of tin(II) chloride, intensely colored brown complexes of rhenium formed on the surface of adsorbents. Electron paramagnetic resonance showed that, in the surface complexes, rhenium is in the oxidation state 2+. Silicas chemically modified by sulfur-containing groups were used in the development of procedures for the sequential isolation and determination of platinum and rhenium in solutions after the decomposition of aluminum-platinum-rhenium catalysts.

Speciation of inorganic selenium in natural water by in situ solid-phase extraction using functionalized silica

“…Silicas modified with mercaptopropyl (MPS) and mercaptophenyl (MPhS) groups were synthesized according to the published procedure. 39…”

“…Silicas modied with mercaptopropyl (MPS) and mercaptophenyl (MPhS) groups were synthesized according to the published procedure. 39 The functional groups of the synthesized adsorbents can be presented as follows:…”

“…The content of another selenium species is found by the difference between the total content and the content of the rst species of selenium. 39 The second approach is based on the extraction of both selenium species using the same adsorbent and their subsequent separation at the desorption stage using selective eluents. 21,36 The most promising is the sequential separation of Se(IV) and Se(VI) in a two-column system using adsorbents that are selective for a certain type of selenium species, their separate elution, and determination by spectroscopic methods.…”

“…The content of another selenium species is found by the difference between the total content and the content of the first species of selenium. 39 The second approach is based on the extraction of both selenium species using the same adsorbent and their subsequent separation at the desorption stage using selective eluents. 21,36…”