Sulfite activation by oxidized pyrite for dye degradation assisted by oxygen

Because pyrite is easily oxidized, the catalytic performance of a pyrite-peroxymonosulfate (PMS) or peroxydisulfate (PDS) activation system will be significantly affected due to the low activation of PMS or PDS by Fe3+ in practical applications. Herein, sulfite was selected to react with oxidized pyrite (OP) to generate radicals for the degradation of dye wastewater in the presence of oxygen because both Fe2+ and Fe3+ can be used as efficient activators of sulfite. Under the optimal conditions, an OP/sodium sulfite (SS) system achieved high-efficiency removal of rhodamine B (RB) in the wide pH range of 4.0-9.0. In the OP/SS system, sulfite was mainly activated by dissolved iron. Moreover, by comparison with an acid-washed pyrite (AWP)/SS system, Fe(iii) on the surface of pyrite, instead of Fe(ii), acted as the active site of sulfite activation in the heterogeneous reaction of the OP/SS system. In addition, good reusability of OP and high decolorization of different dye pollutants made the OP/SS system possibly suitable for application in dye wastewater treatment.

Automated summary

The research found that by reacting sulfite with oxidized pyrite, radicals can be effectively generated to degrade dye wastewater, especially achieving high-efficiency removal of dyes in a wide pH range. Furthermore, sulfite is mainly activated by dissolved iron, with surface Fe(iii) acting as the main activation site.