High-performance reductive decomposition of trichloroacetamide by the vacuum-ultraviolet/sulfite process: Kinetics, mechanism and combined toxicity risk

Deeper Defluorination and Mineralization of a Novel PFECA (C7 HFPO-TA) in Vacuum UV/Sulfite: Unique Mechanism of H/OCF3 Exchange

“…The absorption coefficient of OH – at pH 10.01 and 12 was 0.3218 and 32.18 cm –1 , much higher than 0.2732 cm –1 of C7 HFPO-TA (0.1 mM). In addition, HO • may dissociate to O • – at higher solution pH, lowering its redox potential. , At a solution pH of 3.99, we also observed the degradation decline of C7 HFPO-TA in the VUV process, which may be ascribed to the light screening of H 2 O 2 (ε 185 nm = 341 M –1 cm –1 ) (Table S11), and e aq – scavenging by H + /H • /H 2 O 2 or H 2 CO 3 */HCO 3 – (eq –). , In consideration of the ineffectiveness of HO • , the e aq – or direct photolysis was the main force for the decay of C7 HFPO-TA in the VUV process. normale aq − + normalH • → normalH 2 + OH − goodbreak0em1em⁣ italick = 2.5 × 10 10 .25em normalM − 1 .25em normals − 1 normale aq − + normalH + → normalH • goodbreak0em1em⁣ italick = 2.3 × 10 10 .25em normalM − 1 .25em normals − 1 normale aq ...…”

“…5,5-Dimethyl-1-pyrroline-N-oxide (DMPO) was used as the trapping agent of HO • /SO 4 • – and SO 3 • – as previous researches recommended. , No radicals could be detected in each process under dark condition. The significant characteristic peaks of 1:2:2:1 confirmed the generation of HO • in VUV process . Both peaks of DMPO-HO • and DMPO–SO 4 • – were observed in UV/PS process, implying the conversion between SO 4 • – and HO • via eq and .…”

“…•− as previous researches recommended. 19,38 No radicals could be detected in each process under dark condition. The significant characteristic peaks of 1:2:2:1 confirmed the generation of HO • in VUV process.…”

“…33,34 At a solution pH of 3.99, we also observed the degradation decline of C7 HFPO-TA in the VUV process, which may be ascribed to the light screening of H 2 O 2 (ε 185 nm = 341 M −1 cm −1 ) (Table S11), and e aq − scavenging by H + /H • /H 2 O 2 or H 2 CO 3 */HCO 3 − (eq 5−9). 19,30 In consideration of the ineffectiveness of HO • , 35 the e aq − or direct photolysis was the main force for the decay of C7 HFPO-TA in the VUV process. (5)…”

“…Here, we proposed that the VUV/SF process could achieve a deeper defluorination of C7 HFPO-TA within a short time, as it generated direct photolysis, HO • and e aq − simultaneously. 18,19 The energy of 185 nm (647 kJ mol −1 ) can also contribute to the direct cleavage of C−C (347 kJ mol −1 ) and C−F (552 kJ mol −1 ) bonds. 20 Therefore, we investigated the degradation of C7 HFPO-TA in UV/PS, UV/SF and VUV/SF processes for the first time.…”