Efficient decomposition of environmentally persistent perfluorocarboxylic acids by use of persulfate as a photochemical oxidant.
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 higherthan 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.
Hori
Hisao
H
National Institute of Advanced Industrial Science and Technology, AIST Tsukuba West, 16-1 Onogawa, Tsukuba 305-8569, Japan. h-hori@aist.go.jp
Yamamoto
Ari
A
Hayakawa
Etsuko
E
Taniyasu
Sachi
S
Yamashita
Nobuyoshi
N
Kutsuna
Shuzo
S
Kiatagawa
Hiroshi
H
Arakawa
Ryuichi
R
D002264:Carboxylic Acids / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D005466:Fluorocarbons / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D010777:Photochemistry / Q000379:methods; D010782:Photolysis; D013431:Sulfates / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods*
D002264:Carboxylic Acids; D005466:Fluorocarbons; D013431:Sulfates; D014874:Water Pollutants, Chemical