Abstract: An acidic aqueous medium for contacting and purifying a gas-phase stream by oxidation of a contaminant contained therein. The medium comprises an aqueous medium which contains redox-effective quantities of (1) silver(I) oxidation catalyst, (2) hydrogen peroxide oxidant, (3) silver metal-reoxidation co-catalyst ingredient which forms a cyclic complex with the hydrogen peroxide oxidant, and (4) oxidation-resistant acid. The acidic aqueous medium provides an integrated functionality of components (1) through (4) for the efficient cascade oxidation of a contaminant containing gas stream, and the continuous regeneration of the reduced silver metal catalyst back to the silver(I) oxidation state.

Abstract: A main aspect of this invention is the provision of a liquid medium for scrubbing contaminants from an environmental gas-phase. Toxic chemicals such as phosphine and arsine are removed from a gas-phase stream by contacting the gas-phase stream with an aqueous medium which oxidizes the contaminants to water-soluble or water-dispersible type derivatives. The aqueous medium has a content of redox ingredients illustrated by compounds such as silver nitrate, hydrogen peroxide, sodium tungstate, and sulfuric acid.