Cai, Min-QiMin-QiCaiLin, Hank Hui-HsiangHank Hui-HsiangLinYang, Jheng-SianJheng-SianYangANGELA YU-CHEN LIN2026-02-052026-02-052026-0222132929https://www.scopus.com/record/display.uri?eid=2-s2.0-105026232697&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/735797Far-ultraviolet light at 222 nm (UV222) has attracted considerable attention as a novel light source owing to its safety for both humans and the environment. Peracetic acid (PAA), a promising alternative to chlorine-based disinfectants, has demonstrated effectiveness in water decontamination through the generation of reactive species when combined with UV254 light. This study provides comprehensive investigation of the degradation mechanisms of sulfisoxazole (SFZ), sulfamethoxazole (SMX), and ketamine (KET) in the UV222/PAA system. Compared with direct UV222 photolysis and PAA oxidation in the dark, the degradation of SFZ, SMX, and KET was markedly accelerated and followed pseudo-first-order kinetics under the UV222/PAA system, with half-lives of 1.22, 1.02, and 2.02 min, respectively. SFZ and SMX degraded more rapidly under alkaline conditions, while KET degraded more rapidly under acidic conditions. Hydroxyl radicals (•OH), singlet oxygen (1O2), superoxide radicals (•O2⁻), and carbon-centered radicals were detected. Among the degradation pathways, direct UV222 photolysis and •OH oxidation dominated across all pH values, while other reactive species (including 1O2) contributed substantially to SFZ and SMX degradation under neutral to alkaline conditions. Carbon-centered radicals were found to participate in SFZ degradation. The transformation byproducts of SFZ were further elucidated and compared across direct UV222 photolysis, UV222/H2O2, and UV222/PAA, revealing distinct degradation patterns. Importantly, the target compounds exhibited comparable degradation efficiencies in real water matrices (tap water, drinking water treatment plant influent, and wastewater treatment plant effluent) to those observed in deionized water, underscoring the robustness and practical applicability of the UV222/PAA system.falseKetamine (KET)Peracetic acid (PAA)Sulfamethoxazole (SMX)Sulfisoxazole (SFZ)UV222journal article10.1016/j.jece.2025.1208702-s2.0-105026232697