Abstract
| - The decomposition of persistent and bioaccumulativeperfluorooctanoic acid (PFOA) in water by UV−visible lightirradiation, by H2O2 with UV−visible light irradiation, andby a tungstic heteropolyacid photocatalyst was examined todevelop a technique to counteract stationary sources ofPFOA. Direct photolysis proceeded slowly to produce CO2,F-, and short-chain perfluorocarboxylic acids. Comparedto the direct photolysis, H2O2 was less effective in PFOAdecomposition. On the other hand, the heteropolyacidphotocatalyst led to efficient PFOA decomposition and theproduction of F- ions and CO2. The photocatalyst alsosuppressed the accumulation of short-chain perfluorocarboxylic acids in the reaction solution. PFOA in theconcentrations of 0.34−3.35 mM, typical of those inwastewaters after an emulsifying process in fluoropolymermanufacture, was completely decomposed by the catalystwithin 24 h of irradiation from a 200-W xenon−mercurylamp, with no accompanying catalyst degradation, permittingthe catalyst to be reused in consecutive runs. Gaschromatography/mass spectrometry (GC/MS) measurementsshowed no trace of environmentally undesirable speciessuch as CF4, which has a very high global-warming potential.When the (initial PFOA)/(initial catalyst) molar ratio was 10:1, the turnover number for PFOA decomposition reached4.33 over 24 h of irradiation.
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