Perfluorooctanoic acid degradation in the presence of Fe(III) under natural sunlight.
Due to the high bond dissociation energy (BDE) of CF bonds (116 kcal/mol), perfluorooctanoic acid (PFOA) is a highly recalcitrant pollutant. Herein, we demonstrate a novel method to decompose PFOA in the presence of sunlight and ferric iron (Fe(III)). Under such conditions, 97.8 ± 1.7% of 50 μM PFOA decomposed within 28 days into shorter-chain intermediates and fluoride (F(-)), with an overall defluorination extent of 12.7 ± 0.5%. No PFOA was removed under visible light, indicating that UV radiation is required for PFOA decomposition. Spectroscopic analysis indicates that the decomposition reaction is likely initiated by electron-transfer from PFOA to Fe(III), forming Fe(II) and an unstable organic carboxyl radical. An alternative mechanism for the formation of this organic radical involves hydroxyl radicals, detected by electron paramagnetic resonance (EPR). The observation that PFOA can be degraded by Fe(III) under solar irradiation provides mechanistic insight into a possibly overlooked natural attenuation process. Because Fe(III) is abundant in natural waters and sunlight is essentially free, this work represents a potentially important step toward the development of simple and inexpensive remediation strategies for PFOA-contaminated water.
Beijing Key Laboratory of Water Resource and Environmental Engineering, China University of Geosciences, Beijing 100083, PR China.
Dandan
D
Liu
Zongming
Z
Xiu
Fei
F
Liu
Gang
G
Wu
Dave
D
Adamson
Charles
C
Newell
Peter
P
Vikesland
Ah-Lim
AL
Tsai
Pedro J
PJ
Alvarez
D002210:Caprylates / Q000737:chemistry* / Q000528:radiation effects*; D052918:Environmental Restoration and Remediation; D005290:Ferric Compounds / Q000737:chemistry*; D005466:Fluorocarbons / Q000737:chemistry* / Q000528:radiation effects*; D006861:Hydrogen Peroxide / Q000737:chemistry; D016877:Oxidants / Q000737:chemistry; D017670:Sodium Compounds / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry; D013472:Sunlight; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000528:radiation effects*
D002210:Caprylates; D005290:Ferric Compounds; D005466:Fluorocarbons; D016877:Oxidants; D017670:Sodium Compounds; D013431:Sulfates; D014874:Water Pollutants, Chemical; C024823:ferric sulfate; C023036:perfluorooctanoic acid; D006861:Hydrogen Peroxide; C024625:sodium persulfate
Defluorination; Iron; PFOA; Photolysis; Radical