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Zeng Y, Dai Y, Yin L, Huang J, Hoffmann MR. Rethinking alternatives to fluorinated pops in aqueous environment and corresponding destructive treatment strategies. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 946:174200. [PMID: 38936705 DOI: 10.1016/j.scitotenv.2024.174200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 05/25/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024]
Abstract
Alternatives are being developed to replace fluorinated persistent organic pollutants (POPs) listed in the Stockholm Convention, bypass environmental regulations, and overcome environmental risks. However, the extensive usage of fluorinated POPs alternatives has revealed potential risks such as high exposure levels, long-range transport properties, and physiological toxicity. Therefore, it is imperative to rethink the alternatives and their treatment technologies. This review aims to consider the existing destructive technologies for completely eliminating fluorinated POPs alternatives from the earth based on the updated classification and risks overview. Herein, the types of common alternatives were renewed and categorized, and their risks to the environment and organisms were concluded. The efficiency, effectiveness, energy utilization, sustainability, and cost of various degradation technologies in the treatment of fluorinated POPs alternatives were reviewed and evaluated. Meanwhile, the reaction mechanisms of different fluorinated POPs alternatives are systematically generalized, and the correlation between the structure of alternatives and the degradation characteristics was discussed, providing mechanistic insights for their removal from the environment. Overall, the review supplies a theoretical foundation and reference for the control and treatment of fluorinated POPs alternatives pollution.
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Affiliation(s)
- Yuxin Zeng
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China.
| | - Yunrong Dai
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
| | - Lifeng Yin
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China.
| | - Jun Huang
- State Key Joint Laboratory of Environment Simulation and Pollution Control (SKJLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control (BKLEOC), School of Environment, POPs Research Center, Tsinghua University, Beijing 100084, PR China.
| | - Michael R Hoffmann
- Department of Environmental Science & Engineering, California Institute of Technology, Pasadena, CA 91125, United States.
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2
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Zeidabadi FA, Esfahani EB, McBeath ST, Mohseni M. Managing PFAS exhausted Ion-exchange resins through effective regeneration/electrochemical process. WATER RESEARCH 2024; 255:121529. [PMID: 38554630 DOI: 10.1016/j.watres.2024.121529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 03/03/2024] [Accepted: 03/25/2024] [Indexed: 04/02/2024]
Abstract
This study proposes an integrated approach that combines ion-exchange (IX) and electrochemical technologies to tackle problems associated with PFAS contamination. Our investigation centers on evaluating the recovery and efficiency of IX/electrochemical systems in the presence of five different salts, spanning dosages from 0.1 % to 8 %. The outcomes reveal a slight superiority for NaCl within the regeneration system, with sulfate and bicarbonate also showing comparable efficacy. Notably, the introduction of chloride ion (Cl-) into the electrochemical system results in substantial generation of undesirable chlorate (ClO3-) and perchlorate (ClO4-) by-products, accounting for ∼18 % and ∼81 % of the consumed Cl-, respectively. Several agents, including H2O2, KI, and Na2S2O3, exhibited effective mitigation of ClO3- and ClO4- formation. However, only H2O2 demonstrated a favorable influence on the degradation and defluorination of PFOA. The addition of 0.8 M H2O2 resulted in the near-complete removal of ClO3- and ClO4-, accompanied by 1.3 and 2.2-fold enhancements in the degradation and defluorination of PFOA, respectively. Furthermore, a comparative analysis of different salts in the electrochemical system reveals that Cl- and OH- ions exhibit slower performance, possibly due to competitive interactions with PFOA on the anode's reactive sites. In contrast, sulfate and bicarbonate salts consistently demonstrate robust decomposition efficiencies. Despite the notable enhancement in IX regeneration efficacy facilitated by the presence of methanol, particularly for PFAS-specific resins, this enhancement comes at the cost of reduced electrochemical decomposition of all PFAS. The average decay rate ratio of all PFAS in the presence of 50 % methanol, compared to its absence, falls within the range of 0.11-0.39. In conclusion, the use of 1 % Na2SO4 salt stands out as a favorable option for the integrated IX/electrochemical process. This choice not only eliminates the need to introduce an additional chemical (e.g., H2O2) into the wastewater stream, but also ensures both satisfactory regeneration recovery and efficiency in the decomposition process through electrochemical treatment.
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Affiliation(s)
- Fatemeh Asadi Zeidabadi
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada
| | - Ehsan Banayan Esfahani
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada
| | - Sean T McBeath
- Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Amherst, MA 01003, United States
| | - Madjid Mohseni
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada.
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3
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Asadi Zeidabadi F, Banayan Esfahani E, Moreira R, McBeath ST, Foster J, Mohseni M. Structural dependence of PFAS oxidation in a boron doped diamond-electrochemical system. ENVIRONMENTAL RESEARCH 2024; 246:118103. [PMID: 38181849 DOI: 10.1016/j.envres.2024.118103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 12/11/2023] [Accepted: 01/02/2024] [Indexed: 01/07/2024]
Abstract
Driven by long-term persistence and adverse health impacts of legacy perfluorooctanoic acid (PFOA), production has shifted towards shorter chain analogs (C4, perfluorobutanoic acid (PFBA)) or fluorinated alternatives such as hexafluoropropylene oxide dimer acid (HFPO-DA, known as GenX) and 6:2 fluorotelomer carboxylic acid (6:2 FTCA). Yet, a thorough understanding of treatment processes for these alternatives is limited. Herein, we conducted a comprehensive study using an electrochemical approach with a boron doped diamond anode in Na2SO4 electrolyte for the remediation of PFOA common alternatives, i.e., PFBA, GenX, and 6:2 FTCA. The degradability, fluorine recovery, transformation pathway, and contributions from electro-synthesized radicals were investigated. The results indicated the significance of chain length and structure, with shorter chains being harder to break down (PFBA (65.6 ± 5.0%) < GenX (84.9 ± 3.3%) < PFOA (97.9 ± 0.1%) < 6:2 FTCA (99.4 ± 0.0%) within 120 min of electrolysis). The same by-products were observed during the oxidation of both low and high concentrations of parent PFAS (2 and 20 mg L-1), indicating that the fundamental mechanism of PFAS degradation remained consistent. Nevertheless, the ratio of these by-products to the parent PFAS concentration varied which primarily arises from the more rapid PFAS decomposition at lower dosages. For all experiments, the main mechanism of PFAS oxidation was initiated by direct electron transfer at the anode surface. Sulfate radical (SO4•-) also contributed to the oxidation of all PFAS, while hydroxyl radical (•OH) only played a role in the decomposition of 6:2 FTCA. Total fluorine recovery of PFBA, GenX, and 6:2 FTCA were 96.5%, 94.0%, and 76.4% within 240 min. The more complex transformation pathway of 6:2 FTCA could explain its lower fluorine recovery. Detailed decomposition pathways for each PFAS were also proposed through identifying the generated intermediates and fluorine recovery. The proposed pathways were also assessed using 19F Nuclear Magnetic Resonance (NMR) spectroscopy.
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Affiliation(s)
- Fatemeh Asadi Zeidabadi
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada
| | - Ehsan Banayan Esfahani
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada
| | - Raphaell Moreira
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada
| | - Sean T McBeath
- Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Amherst, MA, 01002, United States
| | - Johan Foster
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada
| | - Madjid Mohseni
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada.
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4
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Hamid N, Junaid M, Sultan M, Yoganandham ST, Chuan OM. The untold story of PFAS alternatives: Insights into the occurrence, ecotoxicological impacts, and removal strategies in the aquatic environment. WATER RESEARCH 2024; 250:121044. [PMID: 38154338 DOI: 10.1016/j.watres.2023.121044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 12/17/2023] [Accepted: 12/18/2023] [Indexed: 12/30/2023]
Abstract
Due to increasing regulations on the production and consumption of legacy per- and polyfluoroalkyl substances (PFAS), the global use of PFAS substitutes increased tremendously, posing serious environmental risks owing to their bioaccumulation, toxicity, and lack of removal strategies. This review summarized the spatial distribution of alternative PFAS and their ecological risks in global freshwater and marine ecosystems. Further, toxicological effects of novel PFAS in various freshwater and marine species were highlighted. Moreover, degradation mechanisms for alternative PFAS removal from aquatic environments were compared and discussed. The spatial distribution showed that 6:2 chlorinated polyfluorinated ether sulfonate (6:2 CI-PFAES, also known as F-53B) was the most dominant emerging PFAS found in freshwater. Additionally, the highest levels of PFBS and PFBA were observed in marine waters (West Pacific Ocean). Moreover, short-chain PFAS exhibited higher concentrations than long-chain congeners. The ecological risk quotients (RQs) for phytoplankton were relatively higher >1 than invertebrates, indicating a higher risk for freshwater phytoplankton species. Similarly, in marine water, the majority of PFAS substitutes exhibited negligible risk for invertebrates and fish, and posed elevated risks for phytoplanktons. Reviewed studies showed that alternative PFAS undergo bioaccumulation and cause deleterious effects such as oxidative stress, hepatoxicity, neurotoxicity, histopathological alterations, behavioral and growth abnormalities, reproductive toxicity and metabolism defects in freshwater and marine species. Regarding PFAS treatment methods, photodegradation, photocatalysis, and adsorption showed promising degradation approaches with efficiencies as high as 90%. Finally, research gaps and future perspectives for alternative PFAS toxicological implications and their removal were offered.
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Affiliation(s)
- Naima Hamid
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia; Ocean Pollution and Ecotoxicology (OPEC) Research Group, Universiti Malaysia Terengganu, Malaysia.
| | - Muhammad Junaid
- College of Marine Sciences, South China Agricultural University, Guangzhou 510641, China.
| | - Marriya Sultan
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing School, University of Chinese Academy of Sciences, Chongqing 400714, China
| | - Suman Thodhal Yoganandham
- Department of Environmental Engineering, Changwon National University, Changwon, 51140, Republic of Korea
| | - Ong Meng Chuan
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia; Ocean Pollution and Ecotoxicology (OPEC) Research Group, Universiti Malaysia Terengganu, Malaysia
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5
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Barisci S, Suri R. Degradation of emerging per- and polyfluoroalkyl substances (PFAS) using an electrochemical plug flow reactor. JOURNAL OF HAZARDOUS MATERIALS 2023; 460:132419. [PMID: 37651931 DOI: 10.1016/j.jhazmat.2023.132419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 08/22/2023] [Accepted: 08/26/2023] [Indexed: 09/02/2023]
Abstract
In recent years, shorter-chain fluorinated compounds have been manufactured as alternatives to legacy per- and polyfluoroalkyl substances (PFAS) after a global ban on some long-chain PFAS. This study is the first to investigate the degradability of emerging PFAS by an electrochemical plug flow reactor (EPFR). Ten different emerging PFAS, representing classes of fluorotelomer alcohol, perfluoroalkyl ether carboxylate, polyfluoroalkyl ethersulfonic acids, perfluoroalkyl ether/polyether carboxylates, perfluoroether sulfonate, N-alkyl perfluoroalkylsulfonamido carboxylate, fluoroalkyl phosphonic acid, and perfluoro alkane sulfonamide were investigated. The process kinetics was performed. The degradation of parent compounds increased with increasing retention time (RT). At 45.2 min of RT, the degradation of parent compounds ranged between 68%-100% with a current density of 17.2 mA/cm2. A linear increase in pseudo-first order rate constants was observed for all PFAS with increasing current density from 5.7 to 28.7 mA/cm2 (R2 > 0.91). The effect of pH, natural organic matter, and bicarbonate on the degradation, defluorination, and fluorine mass balance are reported. Alkaline pH (11) caused a decrease in degradation for all PFAS. While the presence of natural organic matter (NOM) significantly decreased the degradation and defluorination processes, the presence of bicarbonate at all studied concentrations (25, 50, and 100 mg/L) did not affect the process efficiency. The defluorination reduced to 34% from 81% with 15 mg/L NOM. The unknown/undetected fluorine fraction also increased in the presence of 15 mg/L NOM indicating the formation of NOM-PFAS complexes. Additionally, C2-C8 perfluoro carboxylic acids (PFCAs), one perfluoro sulfonic acid (PFSA), two H-PFCAs, and 4:2 fluorotelomer sulfonate (FTS) were identified as degradation byproducts in suspect screening. The electrical energy per order for PFAS ranged between 1.8 and 19.4 kWh/m3. This study demonstrates that emerging types of PFAS can potentially be degraded using an EPFR with relatively low electrical energy requirements.
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Affiliation(s)
- Sibel Barisci
- Temple University, Civil and Environmental Engineering Department, Water and Environmental Technology (WET) Center, 1947 N 12th Street, Philadelphia, PA 19122, USA; Ege University, Bioengineering Department, Bornova, 35100 Izmir, Turkey
| | - Rominder Suri
- Temple University, Civil and Environmental Engineering Department, Water and Environmental Technology (WET) Center, 1947 N 12th Street, Philadelphia, PA 19122, USA.
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6
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Fagan WP, Thayer SR, Weavers LK. Kinetics and Mechanism of Ultrasonic Defluorination of Fluorotelomer Sulfonates. J Phys Chem A 2023. [PMID: 37490391 DOI: 10.1021/acs.jpca.3c03011] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Ultrasound degrades "legacy" per- and polyfluoroalkyl substances (PFAS) via thermolysis at the interface of cavitation bubbles. However, compared to "legacy" PFAS, polyfluoroalkyl substances have a lesser affinity to the interface and may react with •OH. To understand the effect of size on degradation kinetics and mechanism of polyfluoroalkyl substances, this work compared ultrasonic treatment (f = 354 kHz) of n:2 fluorotelomer sulfonates (FTSAs) of varying chain lengths (n = 4, 6, 8). Of the congeners tested, 4:2 fluorotelomer sulfonate (FtS) degraded the fastest in individual solutions and in mixtures. Sonolytic rate constants correlated to diffusion coefficients of FTSAs, indicating that diffuse short-chain FTSAs outcompete long-chain FTSAs to adsorb and react at the bubble interface. Interestingly, 4:2 and 8:2 FtS had different evolutions of fluoride-to-sulfate ratios, [F-]/[SO42-], over time. Initially, [F-]/[SO42-]4:2 FtS and [F-]/[SO42-]8:2 FtS were respectively higher and lower than theoretical ratios. This difference was attributed to the lower maximum surface excess of 8:2 FtS, hindering its ability to pack and, consequently, defluorinate at the interface. In the presence of an •OH scavenger, FTSAs had similar %F- release compared to no scavenger, whereas %SO42- release was drastically diminished. Therefore, thermolysis is the primary degradation pathway of FTSAs; •OH supplements SO42- formation. These results indicate that ultrasound directly cleaves C-F bonds within the fluoroalkyl chain. This work shows that ultrasound efficiently degrades FTSAs of various sizes and may potentially treat other classes of polyfluoroalkyl substances.
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Affiliation(s)
- William P Fagan
- Department of Civil, Environmental, and Geodetic Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Shannon R Thayer
- Department of Civil, Environmental, and Geodetic Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Linda K Weavers
- Department of Civil, Environmental, and Geodetic Engineering, The Ohio State University, Columbus, Ohio 43210, United States
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7
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Mojiri A, Zhou JL, Ozaki N, KarimiDermani B, Razmi E, Kasmuri N. Occurrence of per- and polyfluoroalkyl substances in aquatic environments and their removal by advanced oxidation processes. CHEMOSPHERE 2023; 330:138666. [PMID: 37068615 DOI: 10.1016/j.chemosphere.2023.138666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 03/15/2023] [Accepted: 04/10/2023] [Indexed: 05/14/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS), one of the main categories of emerging contaminants, are a family of fluorinated organic compounds of anthropogenic origin. PFAS can endanger the environment and human health because of their wide application in industries, long-term persistence, unique properties, and bioaccumulation potential. This study sought to explain the accumulation of different PFAS in water bodies. In aquatic environments, PFAS concentrations range extensively from <0.03 (groundwater; Melbourne, Australia) to 51,000 ng/L (Groundwater, Sweden). Additionally, bioaccumulation of PFAS in fish and water biota has been stated to range from 0.2 (Burbot, Lake Vättern, Sweden) to 13,900 ng/g (Bluegill samples, U.S.). Recently, studies have focused on PFAS removal from aqueous solutions; one promising technique is advanced oxidation processes (AOPs), including microwaves, ultrasound, ozonation, photocatalysis, UV, electrochemical oxidation, the Fenton process, and hydrogen peroxide-based and sulfate radical-based systems. The removal efficiency of PFAS ranges from 3% (for MW) to 100% for UV/sulfate radical as a hybrid reactor. Therefore, a hybrid reactor can be used to efficiently degrade and remove PFAS. Developing novel, efficient, cost-effective, and sustainable AOPs for PFAS degradation in water treatment systems is a critical area of research.
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Affiliation(s)
- Amin Mojiri
- Department of Civil and Environmental Engineering, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashihiroshima, 739-8527, Hiroshima, Japan.
| | - John L Zhou
- School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Noriatsu Ozaki
- Department of Civil and Environmental Engineering, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashihiroshima, 739-8527, Hiroshima, Japan
| | - Bahareh KarimiDermani
- Department of Geological Sciences, Hydrogeology, University of Alabama, Tuscaloosa, AL, 35487, USA
| | - Elham Razmi
- Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran
| | - Norhafezah Kasmuri
- School of Civil Engineering, College of Engineering, Universiti Teknologi MARA (UiTM), Shah Alam, 40450, Selangor, Malaysia
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Li Z, Luo ZM, Huang Y, Wang JW, Ouyang G. Recent trends in degradation strategies of PFOA/PFOS substitutes. CHEMOSPHERE 2023; 315:137653. [PMID: 36581124 DOI: 10.1016/j.chemosphere.2022.137653] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
The global elimination and restriction of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), respectively, have urged manufacturers to shift production to their substitutes which still pose threat to the environment with their bioaccumulation, toxicity and migration issues. In this context, efficient technologies and systematic mechanistic studies on the degradation of PFOA/PFOS substitutes are highly desirable. In this review, we summarize the progress in degrading PFOA/PFOS substitutes, including four kinds of mainstream methods. The pros and cons of the present technologies are analyzed, which renders the discussion of future prospects on rational optimizations. Additional discussion is made on the differences in the degradation of various kinds of substitutes, which is compared to the PFOA/PFOS and derives designing principles for more degradable F-containing compounds.
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Affiliation(s)
- Zizi Li
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
| | - Zhi-Mei Luo
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
| | - Yanjun Huang
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
| | - Jia-Wei Wang
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China.
| | - Gangfeng Ouyang
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China.
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Asadi Zeidabadi F, Banayan Esfahani E, McBeath ST, Dubrawski KL, Mohseni M. Electrochemical degradation of PFOA and its common alternatives: Assessment of key parameters, roles of active species, and transformation pathway. CHEMOSPHERE 2023; 315:137743. [PMID: 36608884 DOI: 10.1016/j.chemosphere.2023.137743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/24/2022] [Accepted: 01/02/2023] [Indexed: 06/17/2023]
Abstract
This study investigates an electrochemical approach for the treatment of water polluted with per- and poly-fluoroalkyl substances (PFAS), looking at the impact of different variables, contributions from generated radicals, and degradability of different structures of PFAS. Results obtained from a central composite design (CCD) showed the importance of mass transfer, related to the stirring speed, and the amount of charge passed through the electrodes, related to the current density on decomposition rate of PFOA. The CCD informed optimized operating conditions which we then used to study the impact of solution conditions. Acidic condition, high temperature, and low initial concentration of PFOA accelerated the degradation kinetic, while DO had a negligible effect. The impact of electrolyte concentration depended on the initial concentration of PFOA. At low initial PFOA dosage (0.2 mg L-1), the rate constant increased considerably from 0.079 ± 0.001 to 0.259 ± 0.019 min-1 when sulfate increased from 0.1% to 10%, likely due to the production of SO4•-. However, at higher initial PFOA dosage (20 mg L-1), the rate constant decreased slightly from 0.019 ± 0.001 to 0.015 ± 0.000 min-1, possibly due to the occupation of active anode sites by excess amount of sulfate. SO4•- and •OH played important roles in decomposition and defluorination of PFOA, respectively. PFOA oxidation was initiated by one electron transfer to the anode or SO4•-, undergoing Kolbe decarboxylation where yielded perfluoroalkyl radical followed three reaction pathways with •OH, O2 and/or H2O. PFAS electrooxidation depended on the chemical structures where the decomposition rate constants (min-1) were in the order of 6:2 FTCA (0.031) > PFOA (0.019) > GenX (0.013) > PFBA (0.008). PFBA with a shorter chain length and GenX with -CF3 branching had slower decomposition than PFOA. While presence of C-H bonds makes 6:2 FTCA susceptible to the attack of •OH accelerating its decomposition kinetic. Conducting experiments in mixed solution of all studied PFAS and in natural water showed that the co-presence of PFAS and other water constituents (organic and inorganic matters) had adverse effects on PFAS decomposition efficiency.
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Affiliation(s)
- Fatemeh Asadi Zeidabadi
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada
| | - Ehsan Banayan Esfahani
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada
| | - Sean T McBeath
- Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Amherst, MA 01002, United States
| | - Kristian L Dubrawski
- Department of Civil Engineering, University of Victoria, Victoria, BC, V8P 5C2, Canada
| | - Madjid Mohseni
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, Canada.
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10
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Wang Y, Li L, Huang Q. Electrooxidation of per- and polyfluoroalkyl substances in chloride-containing water on surface-fluorinated Ti 4O 7 anodes: Mitigation and elimination of chlorate and perchlorate formation. CHEMOSPHERE 2022; 307:135877. [PMID: 35931258 DOI: 10.1016/j.chemosphere.2022.135877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/24/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
Electrooxidation (EO) has been shown effective in degrading per- and polyfluoroalkyl substances (PFASs) in water, but concurrent formation of chlorate and perchlorate in the presence of chloride is of concern due to their toxicity. This study examined EO treatment of three representative PFASs, perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and 6:2 fluorotelomer sulfonate (6:2 FTS), in chloride-containing solutions on pristine and surface-fluorinated Ti4O7 anodes having different percentage of surface fluorination. The experiment results indicate that surface fluorination of Ti4O7 anodes slightly inhibited PFAS degradation, while significantly decreased the formation of chlorate and perchlorate. Further studies with spectroscopic and electrochemical characterizations and density functional theory (DFT) computation reveal the mechanisms of the impact on EO performance by anode fluorination. In particular, chlorate and perchlorate formation were fully inhibited when fluorinated Ti4O7 anode was used in reactive electrochemical membrane (REM) under a proper anodic potential range (<3.0 V vs Standard Hydrogen Electrode), resulting from slower intermediate reaction steps and short residence time of the REM system. The results of this study provide a basis for design and optimization of modified Ti4O7 anodes for efficient EO treatment of PFAS while limiting chlorate and perchlorate formation.
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Affiliation(s)
- Yaye Wang
- College of Agricultural and Environmental Sciences, Department of Crop and Soil Sciences, University of Georgia, Griffin, GA, 30223, United States
| | - Lei Li
- College of Agricultural and Environmental Sciences, Department of Crop and Soil Sciences, University of Georgia, Griffin, GA, 30223, United States
| | - Qingguo Huang
- College of Agricultural and Environmental Sciences, Department of Crop and Soil Sciences, University of Georgia, Griffin, GA, 30223, United States.
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11
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Veciana M, Bräunig J, Farhat A, Pype ML, Freguia S, Carvalho G, Keller J, Ledezma P. Electrochemical oxidation processes for PFAS removal from contaminated water and wastewater: fundamentals, gaps and opportunities towards practical implementation. JOURNAL OF HAZARDOUS MATERIALS 2022; 434:128886. [PMID: 35436757 DOI: 10.1016/j.jhazmat.2022.128886] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 03/20/2022] [Accepted: 04/07/2022] [Indexed: 05/27/2023]
Abstract
Electrochemical oxidation (EO) is emerging as one of the most promising methods for the degradation of recalcitrant per- and poly-fluoroalkyl substances (PFASs) in water and wastewater, as these compounds cannot be effectively treated with conventional bio- or chemical approaches. This review examines the state of the art of EO for PFASs destruction, and comprehensively compares operating parameters and treatment performance indicators for both synthetic and real contaminated water and wastewater media. The evaluation shows the need to use environmentally-relevant media to properly quantify the effectiveness/efficiency of EO for PFASs treatment. Additionally, there is currently a lack of quantification of sorption losses, resulting in a likely over-estimation of process' efficiencies. Furthermore, the majority of experimental results to date indicate that short-chain PFASs are the most challenging and need to be prioritized as environmental regulations become more stringent. Finally, and with a perspective towards practical implementation, several operational strategies are proposed, including processes combining up-concentration followed by EO destruction.
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Affiliation(s)
- Mersabel Veciana
- Australian Centre for Water and Environmental Biotechnology, The University of Queensland, Brisbane QLD 4072, Australia.
| | - Jennifer Bräunig
- Queensland Alliance for Environmental Health Sciences, The University of Queensland, Brisbane QLD 4102, Australia
| | - Ali Farhat
- GHD Pty Ltd, Brisbane QLD 4000, Australia
| | - Marie-Laure Pype
- Australian Centre for Water and Environmental Biotechnology, The University of Queensland, Brisbane QLD 4072, Australia
| | - Stefano Freguia
- Department of Chemical Engineering, The University of Melbourne, Parkville VIC 3010, Australia
| | - Gilda Carvalho
- Australian Centre for Water and Environmental Biotechnology, The University of Queensland, Brisbane QLD 4072, Australia
| | - Jürg Keller
- Australian Centre for Water and Environmental Biotechnology, The University of Queensland, Brisbane QLD 4072, Australia
| | - Pablo Ledezma
- Australian Centre for Water and Environmental Biotechnology, The University of Queensland, Brisbane QLD 4072, Australia.
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Enhanced treatment of perfluoroalkyl acids in groundwater by membrane separation and electrochemical oxidation. CHEMICAL ENGINEERING JOURNAL ADVANCES 2020. [DOI: 10.1016/j.ceja.2020.100042] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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Mora-Gómez J, García-Gabaldón M, Carrillo-Abad J, Montañés M, Mestre S, Pérez-Herranz V. Influence of the reactor configuration and the supporting electrolyte concentration on the electrochemical oxidation of Atenolol using BDD and SnO2 ceramic electrodes. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2020.116684] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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14
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Carrillo-Abad J, Mora-Gómez J, García-Gabaldón M, Ortega E, Mestre S, Pérez-Herranz V. Effect of the CuO addition on a Sb-doped SnO 2 ceramic electrode applied to the removal of Norfloxacin in chloride media by electro-oxidation. CHEMOSPHERE 2020; 249:126178. [PMID: 32087454 DOI: 10.1016/j.chemosphere.2020.126178] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/03/2020] [Accepted: 02/09/2020] [Indexed: 06/10/2023]
Abstract
Norfloxacin is employed as in veterinary and human medicine against gram-positive and gram-negative bacteria. Due to the ineffective treatment at the wastewater treatment plants it becomes an emergent pollutant. Electro-oxidation appears as an alternative to its effective mineralization. This work compares Norfloxacin electro-oxidation on different anodic materials: two ceramic electrodes (both based on SnO2 + Sb2O3 with and without CuO, named as CuO and BCE, respectively) and a boron doped diamond (BDD). First, the anodes were characterized by cyclic voltammetry, revealing that NOR direct oxidation occurred at 1.30 V vs. Ag/AgCl. The higher the scan rate the higher both the current density and the anodic potential of the peak. This behavior was analyzed using the Randles-Sevcik equation to calculate the Norfloxacin diffusion coefficient in aqueous media, giving a value of D = 7.80 × 10-6 cm2 s-1 at 25 °C), which is close to the predicted value obtained using the Wilke-Chang correlation. The electrolysis experiments showed that both NOR and TOC decay increased with the applied current density, presenting a pseudo-first order kinetic. All the anodes tested achieved more than 90% NOR degradation at each current density. The CuO is not a good alternative to BCE because although it acts as a catalyst during the first use, it is lost from the anode surface in the subsequent uses. According to their oxidizing power, the anodes employed are ordered as follows: BDD > BCE > CuO.
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Affiliation(s)
- J Carrillo-Abad
- IEC Group, Universitat Politècnica de València, Camí de Vera s/n, 46022, València, Spain
| | - J Mora-Gómez
- IEC Group, Universitat Politècnica de València, Camí de Vera s/n, 46022, València, Spain
| | - M García-Gabaldón
- IEC Group, Universitat Politècnica de València, Camí de Vera s/n, 46022, València, Spain.
| | - E Ortega
- IEC Group, Universitat Politècnica de València, Camí de Vera s/n, 46022, València, Spain
| | - S Mestre
- Instituto de Tecnología Cerámica, Campus Universitario Riu Sec, Av.Vicent Sos Baynat s/n, 12006, Castellón, Spain
| | - V Pérez-Herranz
- IEC Group, Universitat Politècnica de València, Camí de Vera s/n, 46022, València, Spain
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