Photodegradation of perfluorooctanoic acid by 185 nm vacuum ultraviolet light

• Published in: Journal of environmental sciences (China) Vol. 19; no. 4; pp. 387 - 390
• Main Authors: CHEN, Jing, ZHANG, Peng-yi, LIU, Jian
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 2007
• Subjects: Caprylates - radiation effects; Fluorine - chemistry; Fluorocarbons - radiation effects; Nitrogen; perfluorinated carboxylic acid; perfluorooctanoic acid; photodegradation; Ultraviolet Rays; Vacuum; vacuum ultraviolet; Water Pollutants, Chemical - radiation effects; 光降解; 全氟羧酸; 全氟辛酸; 真空紫外光; perfluorooctanoic acid; photodegradation; perfluorinated carboxylic acid; vacuum ultraviolet
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/s1001-0742(07)60064-3

The photodegradation of persistent and bioaccumulative perftuorooctanoic acid （PFOA） in water by 185 nm vacuum ultraviolet （VUV） light was examined to develop an effective technology to deal with PFOA pollution. PFOA degraded very slowly under irradiation of 254 nm UV light. However, 61.7% of initial PFOA was degraded by 185 nm VUV light within 2 h, and defluorination ratio reached 17.1%. Pseudo first-order-kinetics well simulated its degradation and defluorination. Besides, fluoride ion formed in water, 4 shorter-chain perfluorinated carboxylic acids （PFCAs）, that is, perfluoroheptanoic acid, perfluorohexanoic acid, perfluoropentanoic acid, and perfluorobutanoic acid. These were identified as intermediates by LC-MS measurement. These PFCAs consecutively formed and further degraded with irradiation time. According to the mass balance calculation, no other byproducts were formed. It was proposed that PFCAs initially are decarboxylated by 185 nm light, and the radical thus formed reacts with water to form shorter-chain PFCA with one less CF2 unit.