Photodecomposition of Perfluorooctanoic Acid Under UV Light in the Presence of Fe(Ⅲ)

LIU Dandan; XU Rongzhen; LIU Fei

doi:10.3969/j.issn.1003-6504.2017.05.005

Abstract：Perfluorooctanoic acid (PFOA) is the subject of increasing regulatory interest because of its potential to bioaccumulation,its environmental persistence,and growing evidence of its toxicity to humans.Due to the presence of multiple,highly stable C-F bonds,PFOA and other perfluorinated compounds (PFCs) are very persistent under most natural conditions,and the development of effective remediation technologies has proven difficult.It was known that Fe (Ⅲ)is likely to form complex with the compound containing a carboxylic acid group,and the complex is sensitive to UV light.Herein,UV254 light was used to decompose PFOA in the presence of ferric iron (Fe (Ⅲ)).Electron paramagnetic resonance (EPR) was used to investigate the underlying reaction mechanisms and determine if free radicals are generated by Fe (Ⅲ)UV light reaction system.Under such conditions,97.8％ of 48.4 μmol/L PFOA decomposed within 180 mins into shorter-chain intermediates and fluoride (F-),with an overall defluorination extent (fluoride released relative to fluoride present in PFOA) of 26.5％.Radical quenching experiment and spectroscopic analysis indicates that PFOA was degraded step-wisely into shorter-chain intermediates.On the one hand,the hydroxyl radical formed by Fe (Ⅲ) under UV light contribute to the degradation of PFOA,on the other hand,PFOA can form a kind of complex to be active under UV irradiation and step-wisely degraded into shorter-chain.The observation that PFOA can be degraded by Fe (Ⅲ) under UV irradiation provides mechanistic insight into a possibly overlooked natural attenuation process.Because Fe (Ⅲ) is abundant in natural waters and sunlight contains UV light,this study represents a potentially important step towards the development of simple and inexpensive remediation and management strategies for PFOA-contaminated water.