Enhanced degradation of emerging contaminants by Far-UVC photolysis of peracetic acid: Synergistic effect and mechanisms

Krypton chloride (KrCl*) excimer lamps (222 nm) are used as a promising irradiation source to drive ultraviolet-based advanced oxidation processes (UV-AOPs) in water treatment. In this study, the UV₂₂₂/peracetic acid (PAA) process is implemented as a novel UV-AOPs for the degradation of emerging contaminants (ECs) in water. The results demonstrate that UV₂₂₂/PAA process exhibits excellent degradation performance for carbamazepine (CBZ), with a removal rate of 90.8 % within 45 min. Notably, the degradation of CBZ in the UV₂₂₂/PAA process (90.8 %) was significantly higher than that in the UV₂₅₄/PAA process (15.1 %) at the same UV dose. The UV₂₂₂/PAA process exhibits superior electrical energy per order (EE/O) performance while reducing resource consumption associated with the high-energy UV₂₅₄/PAA process. Quenching experiments and electron paramagnetic resonance (EPR) detection confirm that HO• play a dominant role in the reaction. The contributions of direct photolysis, HO•, and other active species (RO• and ¹O₂) are estimated to be 5 %, 88 %, and 7 %, respectively. In addition, the effects of Cl^-, HCO₃^-, and humic acid (HA) on the degradation of CBZ are evaluated. The presence of relatively low concentrations of Cl^-, HCO₃^-, and HA can inhibit CBZ degradation. The UV₂₂₂/PAA oxidation process could also effectively degrade several other ECs (i.e., iohexol, sulfamethoxazole, acetochlor, ibuprofen), indicating the potential application of this process in pollutant removal. These findings will propel the development of the UV₂₂₂/PAA process and provide valuable insights for its application in water treatment.