Quantitative and time-course analysis of microbial degradation of 1H,1H,2H,2H,8H,8H–perfluorododecanol in activated sludge

Abstract

A methylene group in the fluorinated carbon backbone of 1H,1H,2H,2H,8H,8H-perfluorododecanol (degradable telomer fluoroalcohol, DTFA) renders the molecule cleavable by microbial degradation into two fluorinated carboxylic acids. Several biodegradation products of DTFA are known, but their rates of conversion and fates in the environment have not been determined. We used liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) to quantitatively investigate DTFA biodegradation by the microbial community in activated sludge in polyethylene terephthalate (PET) flasks, which we also determined here showed least adsorption of DTFA. A reduction in DTFA concentration in the medium was accompanied by rapid increases in the concentrations of 2H,2H,8H,8H-perfluorododecanoic acid (2H,2H,8H,8H-PFDoA), 2H,8H,8H-2-perfluorododecenoic acid (2H,8H,8H-2-PFUDoA), and 2H,2H,8H-7-perfluorododecenoic acid and 2H,2H,8H-8-perfluorododecenoic acid (2H,2H,8H-7-PFUDoA/2H,2H,8H-8-PFUDoA), which were in turn followed by an increase in 6H,6H-perfluorodecanoic acid (6H,6H-PFDeA) concentration, and decreases in 2H,2H,8H,8H-PFDoA, 2H,8H,8H-2-PFUDoA, and 2H,2H,8H-7-PFUDoA/2H,2H,8H-8-PFUDoA concentrations. Accumulation of perfluorobutanoic acid (PFBA), a presumed end product of DTFA degradation, was also detected. Our quantitative and time-course study of the concentrations of these compounds reveals main routes of DTFA biodegradation, and the presence of new biodegradation pathways.

Development of a PFAS reaction library: identifying plausible transformation pathways in environmental and biological systems

“…Although Ruan et al 65 show 6:2 FTI as the key intermediate that leads to the formation of PFPeA, PFHxA, and 4:3 FTUCA, we concluded that it is actually 5:3 UFTCA is the key intermediate, which forms from 6:2 FTI through multiple steps (pathways d 1d 4 ), that forms PFPeA through multiple intermediates The proposed transformation pathway for the transformation of 1H,1H,2H,2H,8H,8H-peruorododecanol, which is referred to as DTFA (degradable telomer uoro alcohol), in activated sludge 71,76 is illustrated in Fig. 11.…”

“…Further loss of HF from 2 H ,8 H ,8 H -2-PFUDoA through hydrolysis gives 2 H ,8 H -2,8-PFuDoA (pathway D). The formation of 2 H ,8 H -2,8-PFUDoA represents a key branching point for which four pathways to the chain-shortened, terminal carboxylic acids are proposed by Arakaki, 76 ultimately leading to the formation of the chain shortened fluorotelomer carboxylic acids. For the sake of simplicity, we follow only pathway 1 and subsequently the formation of 6-H-6-PFUOA as presented in Arakaki, et al 76 and shown as pathway E in Fig.…”

“…The proposed transformation pathway for the transformation of 1 H ,1 H ,2 H ,2 H ,8 H ,8 H -perfluorododecanol, which is referred to as DTFA (degradable telomer fluoro alcohol), in activated sludge 71,76 is illustrated in Fig. 11.…”

“…Activated sludge 29 15 (4) 10, (2), [6] 13, (2), [7] 18, (3), [10] 25, (5), [16] Activated sludge 71,76 5 Environmental Science: Processes & Impacts Paper PFAS reaction libraries through the CTS. Obviously the greater the number of generations the greater the number of generated TPs and PTPs.…”

“…11. Arakaki et al 76 71 which suggests that further transformation of 6H-6-PFUOA requires cleavage of the CC double bond through an oxidation process such as epoxidation as suggested by Arakaki et al 71 As generated by execution of the PFAS reaction library, formation of the epoxide across the CF]CH bond gives 6,7O-PFDeA (pathway g1), which upon 102 It should be noted that the formation of PFHxDiA was reported in Arakaki, et al, 71 but not in Arakaki, et al 76 Each of the PFAS terminal products experimentally veried by Arakaki et al 76 were generated by the PFAS environmental reaction library.…”