Total organic fluorine (TOF) analysis by completely converting TOF into fluoride with vacuum ultraviolet

Vacuum-UV Radiation Capable of Catalyst-Free Decomposition of 6:2 FTSA: The Transformation Mechanism and Impacts of the Water Matrix

“…As listed in Table , the presence of C–H bonds led to greater ε 185 nm of 6:2 FTSA than those of fully fluorinated PFSAs (see Figure S.4). This observation is in agreement with our earlier findings in the case of difluoroacetic acid (CHF 2 COO – ) and trifluoroacetic acid (CF 3 COO – ) with ε 185 nm of 2858.1 and 2141.9 M –1 cm –1 , respectively . Nonetheless, 6:2 FTSA and studied PFSAs are all poor absorbers of 185 nm, absorbing a trivial fraction of 185 nm ( f 185 nm < 0.0002%, Table S.2), implying the minor contribution of direct photolysis in their decomposition (Section S.3a).…”

“…This observation is in agreement with our earlier findings in the case of difluoroacetic acid (CHF 2 COO − ) and trifluoroacetic acid (CF 3 COO − ) with ε 185 nm of 2858.1 and 2141.9 M −1 cm −1 , respectively. 38 Nonetheless, 6:2 FTSA and studied PFSAs are all poor absorbers of 185 nm, absorbing a trivial fraction of 185 nm (f 185 nm < 0.0002%, Table S.2), implying the minor contribution of direct photolysis in their decomposition (Section S.3a). Thus, such decomposition efficiencies were attributed to the attack of the active agents.…”

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

“…By contrast, the maximum decay/defluorination (99.9%/70.3%) of C7 HFPO-TA in the VUV process occurred at pH 5.98 (Figure S7). The neutral conditions benefited the degradation in the VUV process, which was consistent with the previous study . The decline on the decay and defluorination of C7 HFPO-TA in the VUV process at higher pH may be caused by the light screening of OH – .…”

Photo-chemical/catalytic oxidative/reductive decomposition of per- and poly-fluoroalkyl substances (PFAS), decomposition mechanisms and effects of key factors: a review

“…Studies on ε and Φ of PFAS at different wavelengths of irradiation are scarce. 60,71 Some studies have illustrated the absorption spectrum of several PFAS and showed different propensities of PFAS to absorb and react with photon irradiation. [72][73][74][75] For instance, PFOS has weak absorption from deep ultraviolet (UV) to 220 nm, 74 while PFOA shows a strong absorption spectrum in this range and weak absorption from 220 to 270 nm.…”

“…Comparing different photon wavelengths, higher degradation efficiency of PFOA was observed using UV/VUV (254/185 nm) system rather than UV (254 nm) process. 71,76,82 This could be due to the greater photon energy of 185 nm photons, stronger photon absorption of PFOA in VUV region, and the attack of VUV-induced active agents. However, a point to be noted here is that in real case scenarios where PFAS concentrations are several orders of magnitude lower than that of water (55.5 mol L −1 ) and due to the strong absorptivity of water in VUV region, VUV photons are exclusively absorbed by water molecules.…”