2017 Volume 43 Issue 4 Pages 252-257
Chelating agents were used to accelerate the photodegradation of perfluorooctanoic acid (PFOA) catalyzed by Fe3+. Citrate, oxalate, and EDTA as chelating groups each accelerated the catalytic photodegradation to a similar degree. The dissolved iron concentration in the Fe-citrate system with equimolar amounts of citrate and Fe3+ was about 1.8 times higher than that in the absence of chelating agent, indicating that the higher concentration of dissolved iron was a factor in the acceleration. Since about 70% of the added Fe3+ remained in solution in the Fe-citrate system, use of a higher molar ratio of citrate did not result in further acceleration of the PFOA photodegradation. As for the mass balance of fluorine, the use of Fe3+ in combination with citrate resulted in much more defluorination of the PFOA molecules and the resultant perfluoro intermediates. The acceleration resulting from the combined use of Fe3+ and citrate was diminished by increase of the UV light power from 14 to 40 W.