Efficient Decomposition of Environmentally Persistent Perfluorocarboxylic Acids by Use of Persulfate as a Photochemical Oxidant

• Published in: Environmental science & technology 2005-04, Vol.39 (7), p.2383-2388
• Main Authors: Hori, Hisao, Yamamoto, Ari, Hayakawa, Etsuko, Taniyasu, Sachi, Yamashita, Nobuyoshi, Kutsuna, Shuzo, Kiatagawa, Hiroshi, Arakawa, Ryuichi
• Format: Article
• Language: English
• Subjects: Acids; Applied sciences; Carboxylic Acids - chemistry; Chemicals; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Decomposition; Exact sciences and technology; Fluorocarbons - chemistry; Gas Chromatography-Mass Spectrometry; Industrial wastewaters; Oxidation; Photochemistry - methods; Photolysis; Pollution; Sulfates - chemistry; Waste Disposal, Fluid - methods; Wastewaters; Water Pollutants, Chemical; Water Purification - methods; Water treatment and pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es0484754

Photochemical decomposition of persistent perfluorocarboxylic acids (PFCAs) in water by use of persulfate ion (S2O8 2-) was examined to develop a technique to neutralize stationary sources of PFCAs. Photolysis of S2O8 2- produced highly oxidative sulfate radical anions (SO4 •-), which efficiently decomposed perfluorooctanoic acid (PFOA) and other PFCAs bearing C4−C8 perfluoroalkyl groups. The major products were F- and CO2; also, small amounts of PFCAs with shorter than initial chain lengths were detected in the reaction solution. PFOA at a concentration of 1.35 mM (typical of that in untreated wastewater after an emulsifying process in fluoropolymer manufacture) was completely decomposed by a photochemical system with 50 mM S2O8 2- and 4 h of irradiation from a 200-W xenon−mercury lamp. The initial PFOA decomposition rate was 11 times higher than with photolysis alone. All sulfur-containing species in the reaction solution were eventually transformed to sulfate ions by this method. This method was successfully applied to the decomposition of perfluorononanoic acid contained in a floor wax solution.