Chapter 4: Reactive Oxygen Species in Catalytically Activated Peroxydisulfate

Although there has been an exponential increase in basic research in the field of peroxydisulfate (PDS; S₂O₈²⁻) chemistry in recent years, many problems still need to be resolved. Primarily, the mechanism behind the formation of the reactive oxygen species from PDS often remains unclear. Reactive oxygen species are short-lived, fast-reacting molecules/ions/atoms, and there are ongoing debates among scientists about the type of species generated from several specific activation methods. This chapter presents state-of-the-art knowledge about the formation of reactive oxygen species in catalyzed-peroxydisulfate systems. The influence of pH, water matrix constituents, and catalyst type on reactive oxygen species formation (and their interconversion) from PDS is presented. It is believed that this chapter will help readers to better understand the processes taking place in peroxydisulfate-based systems.