Electrochemical Transformations of Perfluoroalkyl Acid (PFAA) Precursors and PFAAs in Landfill Leachates

Abstract

Landfill leachates possess a countless number of chemical classes of potential environmental and human concern, including per- and polyfluoroalkyl substances (PFAS). While detection and biodegradation studies of PFAS in leachates have been conducted previously, the degradation of precursors of perfluoroalkyl acids (PFAAs) in landfill leachates with oxidative technologies has not been addressed. Thus, information regarding the oxidative transformations of PFAA precursors typically present in leachates is lacking. Target and suspect PFAS were identified in a landfill leachate, and their concentrations during electrochemical treatment were quantified over time. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF) measurements of the leachate showed a total PFAS concentration of 157 ± 10 nmol/L that included 53 PFAS and 19 different classes. Multiple PFAS are reported for the first time in landfill leachates. The molar composition of the leachate was comprised of 33% PFAAs, 7% electrochemical fluorination (ECF) precursors, and 60% fluorotelomer (FT) precursors. Further analysis with total oxidizable precursor (TOP) assay revealed an additional concentration of precursors that was not identified with LC-QToF. The evaluation of the intermediate and final products generated during the electrochemical treatment showed evidence of known electrochemical degradation pathways. However, this is the first study to have more evidence for electrochemical pathways in landfill leachates. In brief, sulfonamide-based precursors and fluorotelomer-based precursors were electrochemically transformed into perfluoroalkyl carboxylic acids (PFCAs) during treatment of the leachate.

PFAS-Contaminated Soil Site in Germany: Nontarget Screening before and after Direct TOP Assay by Kendrick Mass Defect and FindPFΔS

“…Since SF 5 -PFSAs are perfluorinated and were not transformed in the dTOP assay (see the following section), the unsaturated SF 5 -PFSAs are expected to be side products rather than transformation products. In general, PFAS with SF 5 groups were detected in AFFFs and commercial products, ,, in biosolids and organic waste, as well as in landfill leachates, and waste water related to electronics fabrication, however, to our knowledge never as the primary PFAS contamination. Barzen-Hanson et al (2017) found SF 5 -PFAS in 3M patents from 1992 and detected them in technical products but not in groundwater.…”

“…Due to the fact that SF 5 -PFSAs seem to be the major PFAS contaminants in the BS-NRW soil, it is reasonable to assume that the contamination of the BS-NRW soil goes back to specific sources and unknown products. Previously reported SF 5 -PFAS in environmental samples were minor contaminants compared to other detected PFAS. , …”

“…Previously reported SF 5 -PFAS in environmental samples were minor contaminants compared to other detected PFAS. 7,25 Perfluoroalkyl Sulfonic Acids (PFSAs). C 4 , C 6 , and C 8 PFSAs were already detected in 2006 in the BS-NRW soil (later also C 9−10 ), 18,21 in the adjacent creek Steinebecke, in following downstream rivers such as the Moḧne River, and in drinking water.…”

Flow-Through Electrochemical Activation of Persulfate for Efficient Wastewater Treatment using Ti4O7 Reactive Electrochemical Membranes

“…The heterogeneous CPAO process includes two steps: () the diffusion of persulfate to the cathode surface from bulk solution (i.e., mass-transfer) , and () the activation of persulfate to produce SO 4 •– (i.e., charge-transfer) . Current studies on the CPAO process, using conventional electrochemical reactors with parallel plates operated in the batch/flow-by mode, commonly featured a poor mass-transfer performance, resulting in the low efficiency of persulfate activation and long hydraulic retention times (e.g., several hours) for water treatment .…”

Unveiling the Key Roles of Various Reactive Species for Ammonia Oxidation in an Efficient Three-Dimensional Electrocatalytic System and Enlarged Scale Study for the Treatment of Practical Wastewater

“…Ammonia-nitrogen is a ubiquitous pollutant in different kinds of wastewater and discharge of this critical nutrient into waterbody that will lead to water body eutrophication and exhibit potential risks to aquatic life. Conventional microbial processes based on ammonia removal techniques are suitable for centralized sewage water treatment, whereas the physicochemical approaches, such as membrane separation, ion exchange, air stripping, breakpoint chlorination, and advanced oxidation techniques, are suitable for small scale or in situ water or wastewater treatment. − Among the different types of physicochemical approaches, electrochemical (EC) oxidation of ammonia, particularly indirect EC oxidation relying on in situ producing reactive chlorine species, exhibits promising application prospect for the treatment of different types of wastewater containing ammonia and chloride ion, which attracts significant attention in academic research and industrial application. − …”