Reductive defluorination of perfluorooctanoic acid by hydrated electrons in a sulfite-mediated UV photochemical system.
A method for reductive degradation of perfluorooctanoic acid (PFOA) was established by using a sulfite/UV process. This process led to a PFOA removal of 100% at about 1h and a defluorination ratio of 88.5% at reaction time of 24h under N2 atmosphere, whereas the use of either UV irradiation or SO3(2-) alone induced little defluorination of PFOA under the same conditions. It was confirmed that the reductive defluorination of PFOA was achieved by hydrated electrons being generated from the photo-conversion of SO3(2-) as a mediator. Theoretical reaction kinetic analysis demonstrated that the generation of hydrated electrons was promoted by increasing either SO3(2-) concentration or solution pH, leading to the acceleration of the PFOA defluorination. Accompanying the reduction of PFOA, a small amount of short-chain perfluorocarboxylic acids, less fluorinated carboxylic acids and perfluorinated alkyl sulfonates were generated, all of which were able to be further degraded with further releasing of fluoride ions. Based on the generation, accumulation and distribution of intermediates, hydrated electrons induced defluorination pathway of PFOA was proposed in a sulfite-mediated UV photochemical system.
Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan 430074, PR China; College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China.
Zhou
Z
Song
Heqing
H
Tang
Nan
N
Wang
Lihua
L
Zhu
D002210:Caprylates / Q000737:chemistry*; D004583:Electrons; D005461:Fluorine / Q000302:isolation & purification*; D005466:Fluorocarbons / Q000737:chemistry*; D007700:Kinetics; D055668:Photochemical Processes; D014466:Ultraviolet Rays
D002210:Caprylates; D005466:Fluorocarbons; D005461:Fluorine; C023036:perfluorooctanoic acid
Hydrated electron; Perfluorooctanoic acid; Photochemical reduction; Sulfite