Advanced Reduction Processes (ARPs) for the degradation of man-made compounds: A UV-C/Sulfite Approach

Advanced Reduction Processes (ARPs) have attracted increasing interest from the scientific community for the treatment of recalcitrant compounds from water. Such processes are based on the formation of highly reactive hydrated electrons (e⁻ₐ_q), which are capable to break strong chemical bonds. Per- and polyfluoroalkyl substances (PFASs) is a category of man-made chemicals. In particular, perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), are highly persistent environmental contaminants, containing carbon–fluorine (C-F) bonds. Due to their widespread use in industrial and consumer products, including, amongst others, paints, textiles, non-stick coatings and firefighting foams, they have been frequently detected in water samples globally (PFOS: 0.002–187 ng L⁻¹; PFOA: 0.001–1371 ng L⁻¹). Their resistance to conventional treatment methods necessitates advanced remediation strategies. Based on the above, the present study evaluates the efficacy of ARPs, specifically the UV-C/sulfite system, for the degradation of PFOS and PFOA in aqueous solutions.

The UV-C/sulfite ARP system generates hydrated electrons (e⁻ₐ_q) and sulfur trioxide anion radicals (SO₃•⁻), which effectively cleave C–F bonds in PFASs. Experiments demonstrated that degradation efficiency was strongly dependent on sulfite concentration, with near-complete removal (>99%) achieved at optimal conditions within 210 minutes. These findings highlight UV/sulfite ARPs as a promising and efficient technology for PFAS remediation in contaminated water.