Photochemical decomposition of perfluorooctanoic acid in aqueous periodate with VUV and UV light irradiation

Abstract

The photochemical decomposition of perfluorooctanoic acid (PFOA) in aqueous periodate (IO4-) was investigated under two types of low-pressure mercury lamps: one emits at 254nm light (UV light) and the other emits both 254nm and 185nm light (VUV light). PFOA decomposed efficiently under VUV light irradiation while it decomposed poorly under UV light irradiation. The addition of IO4- significantly increased the rate of decomposition and defluorination of PFOA irradiated with UV light whereas it decreased both processes under VUV irradiation. Reactive radical (IO3) generated by photolysis of IO4- initiated the oxidation of PFOA in UV process. Aquated electrons (eaq-), generated from water homolysis, scavenged IO4- resulting in decrease of reactive radical species production and PFOA decomposition. The shorter-chain perfluorocarboxylic acids (PFCAs) formed in a stepwise manner from long-chain PFCAs. © 2010 Elsevier B.V.