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Electrochemical degradation of per- and poly-fluoroalkyl substances (PFAS) Asadi Zeidabadi, Fatemeh
Abstract
The global spread of over 14,000 per- and poly-fluoroalkyl substances (PFAS) has raised environmental concerns, triggering substantial efforts in developing PFAS treatment technologies. This study focuses on the applications of boron-doped diamond-electrochemical processes for remediation of PFAS-contaminated waters. Perfluorooctanoic acid (PFOA) and its common alternatives, including perfluorobutanoic acid (PFBA), hexafluoropropylene oxide dimer acid (HFPO-DA/GenX), and 6:2 fluorotelomer carboxylic acid (6:2 FTCA) were selected as representative of legacy, emerging, and precursor PFAS. This research offers valuable insights into the impact of key operational and solution parameters on the efficiency of electrochemical systems. Subsequently, the degradability, fluorine recovery, transformation pathway, and contributions from electro-synthesized radicals for the studied PFAS were investigated. The results indicated the significance of chain length and structure, with slower decay rate (min-1) obtained for shorter chains: PFBA (0.008)<GenX (0.013)<PFOA (0.019)<6:2 FTCA (0.031). Along with the main contribution of direct electron transfer (DET) in destruction of the studied PFAS, results indicated important role of SO₄˙ˉ in oxidizing all PFAS, while ˙OH only involved in 6:2 FTCA decomposition. Proposed decomposition pathways suggested that upon DET to the anode and the attack of active species, PFAS could undergo different pathways: (1) functional group cleavage such as -COOˉ in the case of PFCAs and GenX or -CH₂OOˉ for 6:2 FTCA, (2) breakage of etheric bond in GenX, and (3) H-abstraction by the attack of ˙OH to non-fluorinated carbon in 6:2 FTCA. This work is the first to comprehensively investigate the integrated ion-exchange (IX) and electrochemical processes for sustainable PFAS treatment, evaluating system efficiency with various salts ranging from 0.1% to 8%. The findings revealed the potential of alternative salts, such as sulfate and bicarbonate, for superior effectiveness in electrochemical system when compared to the commonly used NaCl. Notably, chloride demonstrated adverse effects, leading to decreased efficiency and the generation of undesirable by-products such as chlorate and perchlorate. The study also investigates the impact of coexisting organic and inorganic constituents on the efficacy of IX/electrochemical process and provides valuable insights into the application of electrochemical process for treating real water samples (e.g., IX brine solution and landfill leachate), enriching water purification methodologies.
Item Metadata
Title |
Electrochemical degradation of per- and poly-fluoroalkyl substances (PFAS)
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Creator | |
Supervisor | |
Publisher |
University of British Columbia
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Date Issued |
2024
|
Description |
The global spread of over 14,000 per- and poly-fluoroalkyl substances (PFAS) has raised
environmental concerns, triggering substantial efforts in developing PFAS treatment technologies.
This study focuses on the applications of boron-doped diamond-electrochemical processes for
remediation of PFAS-contaminated waters. Perfluorooctanoic acid (PFOA) and its common
alternatives, including perfluorobutanoic acid (PFBA), hexafluoropropylene oxide dimer acid
(HFPO-DA/GenX), and 6:2 fluorotelomer carboxylic acid (6:2 FTCA) were selected as
representative of legacy, emerging, and precursor PFAS. This research offers valuable insights
into the impact of key operational and solution parameters on the efficiency of electrochemical
systems. Subsequently, the degradability, fluorine recovery, transformation pathway, and
contributions from electro-synthesized radicals for the studied PFAS were investigated. The results
indicated the significance of chain length and structure, with slower decay rate (min-1) obtained
for shorter chains: PFBA (0.008)<GenX (0.013)<PFOA (0.019)<6:2 FTCA (0.031). Along with
the main contribution of direct electron transfer (DET) in destruction of the studied PFAS, results
indicated important role of SO₄˙ˉ in oxidizing all PFAS, while ˙OH only involved in 6:2 FTCA
decomposition. Proposed decomposition pathways suggested that upon DET to the anode and the
attack of active species, PFAS could undergo different pathways: (1) functional group cleavage
such as -COOˉ in the case of PFCAs and GenX or -CH₂OOˉ for 6:2 FTCA, (2) breakage of
etheric bond in GenX, and (3) H-abstraction by the attack of ˙OH to non-fluorinated carbon in 6:2
FTCA.
This work is the first to comprehensively investigate the integrated ion-exchange (IX) and
electrochemical processes for sustainable PFAS treatment, evaluating system efficiency with
various salts ranging from 0.1% to 8%. The findings revealed the potential of alternative salts,
such as sulfate and bicarbonate, for superior effectiveness in electrochemical system when
compared to the commonly used NaCl. Notably, chloride demonstrated adverse effects, leading to
decreased efficiency and the generation of undesirable by-products such as chlorate and
perchlorate. The study also investigates the impact of coexisting organic and inorganic constituents
on the efficacy of IX/electrochemical process and provides valuable insights into the application
of electrochemical process for treating real water samples (e.g., IX brine solution and landfill
leachate), enriching water purification methodologies.
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Genre | |
Type | |
Language |
eng
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Date Available |
2025-04-30
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0441014
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2024-05
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International