Adsorption and photosensitized oxidation of sulfide ions on aluminum tetrasulfophthalocyanine-loaded anionic resin

Abstract

Oxidation of inorganic sulfide in water by molecular oxygen was studied under visible light ( λ ≥ 450 nm) irradiation in the presence of immobilized aluminum tetrasulfophthalocyanine (AlPcTS) on a commercial anionic resin Amberlite IRA 400. The composite catalyst exhibited not only a good capacity for uptake of sulfide ions from water, but also a higher photoactivity for the sensitized oxidation of sulfide, as compared to the unbound AlPcTS. Ionic chromatography analysis showed that sulfite and thiosulfate were the reaction intermediates, which were finally oxidized into sulfate. Although the intermediates competed with sulfide for the adsorption sites and active oxygen, the final product of sulfate did not show significant effect both on the adsorption and photosensitized oxidation of sulfide. Five repeated experiments showed that the immobilized sensitizer was reasonably stable and could be repeatedly used for the sulfide oxidation by molecular oxygen under visible light irradiation. The effects of experimental parameters such as AlPcTS loading and sulfide concentration were also examined and discussed in the text.