Peroxydisulfatebased

Peroxydisulfate-based refers to systems that use persulfate salts, such as potassium persulfate (K2S2O8), sodium persulfate (Na2S2O8), or ammonium persulfate ((NH4)2S2O8), as the oxidant source or as a precursor to sulfate radicals. In aqueous chemistry and environmental engineering, persulfate-based oxidants are activated to generate sulfate radicals (SO4•−), which can oxidize a wide range of organic and inorganic pollutants.

Activation methods include heat (typically 40–90°C), ultraviolet light, and transition-metal catalysis (for example Fe2+ in a Fe2+/S2O8^2− system, a Fenton-like process), as well as alkaline or electrochemical activation. Activation converts S2O8^2− into sulfate radicals and other reactive species, increasing oxidant efficiency.

Sulfate radicals attack contaminants by electron transfer, hydrogen abstraction, or addition reactions, often leading to rapid fragmentation or mineralization. The standard redox potential of SO4•− is high, around 2.6–3.1 V, enabling effective oxidation over a broad pH range, though efficiency is influenced by pH, inorganic scavengers, and natural organic matter.

Applications include advanced oxidation processes for water and wastewater treatment, groundwater remediation, and industrial effluent treatment. Persulfate-based systems are also used as radical initiators for polymerization. Compared with hydroxyl radical systems, sulfate radicals can offer different selectivity and performance, but require energy input or catalysts and can be sensitive to scavengers.

Safety and handling: persulfate salts are strong oxidizers; they should be stored away from reducing agents and organic materials and handled with appropriate protective equipment. They are typically used as dry powders or in aqueous solutions with controlled concentrations.