Decomposition of environmentally persistent trifluoroacetic acid to fluoride ions by a homogeneous photocatalyst in water.
Decomposition of trifluoroacetic acid (TFA) was achieved with a tungstic heteropolyacid photocatalyst H3PW12O40*6H2O in order to develop a technique for measures against TFA stationary sources. This is the first example of C-F bond cleavage in an environmentally harmful perfluoromethyl-group-containing compound using a homogeneous photocatalyst. The catalytic reaction proceeds in water at room temperature under UV-visible light irradiation in the presence of oxygen. The system produces only F- ions and CO2; the (mole of formed F-)/(mole of decomposed TFA) and (mole of formed CO2)/(mole of decomposed TFA) ratios were 2.91 and 2.09, respectively. GC/MS measurements showed no trace of other species such as environmentally undesirable CF4, which is the most stable perfluorocarbon and has a very high global warming potential. When the (initial TFA)/(initial catalyst) molar ratio was 20:1, the turnover number of TFA decomposition reached 5.58 by 72 h of irradiation, accompanying with no catalyst degradation. The catalytic reaction mechanism can be explained by a redox reaction between the catalyst and TFA, involving a photo-Kolbe process.
Hori
Hisao
H
National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba West, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan. h-hori@aist.go.jp
Takano
Yuko
Y
Koike
Kazuhide
K
Takeuchi
Koji
K
Einaga
Hisahiro
H
D002384:Catalysis; D005459:Fluorides / Q000737:chemistry*; D010777:Photochemistry; D013696:Temperature; D014269:Trifluoroacetic Acid / Q000737:chemistry*; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods*
D014874:Water Pollutants, Chemical; D014269:Trifluoroacetic Acid; D005459:Fluorides