1
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Weber NH, Redfern H, Grimison CC, Lucas JA, Mackie JC, Stockenhuber M, Kennedy EM. Formation of Products of Incomplete Destruction (PID) from the Thermal Oxidative Decomposition of Perfluorooctanoic Acid (PFOA): Measurement, Modeling, and Reaction Pathways. J Phys Chem A 2024. [PMID: 38935631 DOI: 10.1021/acs.jpca.4c01909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
The thermal decomposition of perfluorooctanoic acid (PFOA) under oxidative conditions was investigated using air (O2) and N2O as oxidants over temperatures ranging from 400 to 1000 °C in an α-alumina reactor. In the presence of air, PFOA was found to decompose into perfluorohept-1-ene (C7F14) and perfluoroheptanoyl fluoride (C7F14O) in addition to HF, CO, and CO2. At temperatures above 800 °C, both C7F14 and C7F14O were no longer detected. A comprehensive analysis of the reaction mechanisms through quantum chemical analysis and kinetic modeling in combination with experimental observations was utilized to identify key reaction pathways. Quantum chemical analysis led to the conclusion that oxygen atoms are crucial in decomposing perfluoroalk-1-enes, especially the stable perfluorohept-1-ene (C7F14). Under oxidative conditions, it was found that significant quantities of C2F6 and CF4 were formed. Further quantum chemical analysis suggests that the O atoms facilitate the formation of volatile fluorinated compounds (VFCs) such as tetrafluoromethane (CF4) and hexafluoroethane (C2F6), particularly at higher temperatures. By elucidating these key reactions, an improved understanding of the potential formation products of incomplete combustion (PICs) or products of incomplete destruction (PIDs) is made.
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Affiliation(s)
- Nathan H Weber
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, NSW 2308, Australia
- Oak Ridge Institute for Science and Education, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Hayden Redfern
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, NSW 2308, Australia
| | | | - John A Lucas
- Ventia Services Pty Ltd, North Sydney, NSW 2060, Australia
| | - John C Mackie
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Michael Stockenhuber
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Eric M Kennedy
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, NSW 2308, Australia
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2
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Hughey KD, Gallagher NB, Zhao Y, Thakur N, Bradley AM, Koster van Groos PG, Johnson TJ. PFAS remediation: Evaluating the infrared spectra of complex gaseous mixtures to determine the efficacy of thermal decomposition of PFAS. CHEMOSPHERE 2024; 362:142631. [PMID: 38885768 DOI: 10.1016/j.chemosphere.2024.142631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 06/13/2024] [Accepted: 06/14/2024] [Indexed: 06/20/2024]
Abstract
Due to their widespread production and known environmental contamination, the need for the detection and remediation of per- and polyfluoroalkyl substances (PFAS) has grown quickly. While destructive thermal treatment of PFAS at low temperatures (e.g., 200-500 °C) is of interest due to lower energy and infrastructure requirements, the range of possible degradation products remains underexplored. To better understand the low temperature decomposition of PFAS species, we have coupled gas-phase infrared spectroscopy with a multivariate curve resolution (MCR) analysis and a database of high-resolution PFAS infrared reference spectra to characterize and quantify a complex mixture resulting from potassium perfluorooctanesulfonate (PFOS-K) decomposition. Beginning at 375 °C, nine prevalent decomposition products (namely smaller perfluorocarbon species) are identified and quantified.
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Affiliation(s)
- Kendall D Hughey
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA
| | - Neal B Gallagher
- Eigenvector Research, Inc., 196 Hyacinth Road, Manson, WA 98831, USA
| | - Yuwei Zhao
- APTIM, 17 Princess Road, Lawrenceville, NJ 08648, USA
| | - Nikita Thakur
- APTIM, 17 Princess Road, Lawrenceville, NJ 08648, USA
| | - Ashley M Bradley
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA
| | | | - Timothy J Johnson
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA.
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3
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Fuller ME, Zhao Y, Hedman PC, Koster van Groos PG, Soto A, Boodoo F, Yniguez J, McKenzie ER. Sonochemical degradation of PFAS in ion exchange regeneration wastes. JOURNAL OF HAZARDOUS MATERIALS 2024; 471:134291. [PMID: 38636231 DOI: 10.1016/j.jhazmat.2024.134291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 03/27/2024] [Accepted: 04/10/2024] [Indexed: 04/20/2024]
Abstract
One of the primary technologies currently being deployed for the removal of per- and polyfluoroalkyl substances (PFAS) from water is ion exchange (IX). For regenerable IX resins, concentrated PFAS in the resulting spent brine and/or still bottoms requires further treatment. This research demonstrated that PFAS in spent brine and still bottoms can be effectively degraded sonochemically at 1000 kHz. Overall, PFAS degradation was negatively impacted by high total organic carbon (TOC) and residual methanol (MeOH) solvent (up to 50 g/kg; 5% w:w), but was enhanced by the high chloride. The addition of caustic (up to 1 N NaOH) partially mitigated the inhibition by TOC and MeOH. Sonochemical degradation of individual PFAS compounds resulted in significant mineralization to form inorganic fluoride, but small quantities of volatile organic fluorine species (VOF) were noted. This is believed to be the first report of sonochemical degradation of PFAS in ion exchange regeneration wastes, and indicates the possibility for the application of this technology as part of a complete PFAS capture and destruction treatment train.
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Affiliation(s)
- Mark E Fuller
- Aptim Federal Services, 17 Princess Road, Lawrenceville, NJ 08648, USA.
| | - Yuwei Zhao
- Aptim Federal Services, 17 Princess Road, Lawrenceville, NJ 08648, USA
| | - Paul C Hedman
- Aptim Federal Services, 17 Princess Road, Lawrenceville, NJ 08648, USA
| | | | - Anthony Soto
- Aptim Federal Services, 17 Princess Road, Lawrenceville, NJ 08648, USA
| | - Francis Boodoo
- Purolite Corporation (An Ecolab Company), King of Prussia, PA 19406, USA
| | - Jord Yniguez
- Purolite Corporation (An Ecolab Company), King of Prussia, PA 19406, USA
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4
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Abeywardane K, Goldsmith CF. Accurate Enthalpies of Formation for PFAS from First-Principles: Combining Different Levels of Theory in a Generalized Thermochemical Hierarchy. ACS PHYSICAL CHEMISTRY AU 2024; 4:247-258. [PMID: 38800729 PMCID: PMC11117692 DOI: 10.1021/acsphyschemau.3c00056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 01/05/2024] [Accepted: 01/08/2024] [Indexed: 05/29/2024]
Abstract
The enthalpies of formation are computed for a large number of per- and poly fluoroalkyl substances (PFAS) using a connectivity-based hierarchy (CBH) approach. A combination of different electronic structure methods are used to provide the reference data in a hierarchical manner. The ANL0 method, in conjunction with the active thermochemical tables, provides enthalpies of formation for smaller species with subchemical accuracy. Coupled-cluster theory with explicit correlations are used to compute enthalpies of formation for intermediate species, based upon the ANL0 results. For the largest PFAS, including perfluorooctanoic acid (PFOA) and heptafluoropropylene oxide dimer acid (GenX), coupled-cluster theory with local correlations is used. The sequence of homodesmotic reactions proposed by the CBH are determined automatically by a new open-source code, AutoCBH. The results are the first reported enthalpies of formation for the majority of the species. A convergence analysis and global uncertainty quantification confirm that the enthalpies of formation at 0 K should be accurate to within ±5 kJ/mol. This new approach is not limited to PFAS, but can be applied to many chemical systems.
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Affiliation(s)
- Kento Abeywardane
- Chemical Engineering Group, School
of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - C. Franklin Goldsmith
- Chemical Engineering Group, School
of Engineering, Brown University, Providence, Rhode Island 02912, United States
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5
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de Souza BB, Meegoda J. Insights into PFAS environmental fate through computational chemistry: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 926:171738. [PMID: 38494023 DOI: 10.1016/j.scitotenv.2024.171738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 02/28/2024] [Accepted: 03/14/2024] [Indexed: 03/19/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are widely used chemicals that exhibit exceptional chemical and thermal stability. However, their resistance to degradation has led to their widespread environmental contamination. PFAS also negatively affect the environment and other organisms, highlighting the need for effective remediation methods to mitigate their presence and prevent further contamination. Computational chemistry methods, such as Density Functional Theory (DFT) and Molecular Dynamics (MD) offer valuable tools for studying PFAS and simulating their interactions with other molecules. This review explores how computational chemistry methods contribute to understanding and tackling PFAS in the environment. PFAS have been extensively studied using DFT and MD, each method offering unique advantages and computational limitations. MD simulates large macromolecules systems however it lacks the ability model chemical reactions, while DFT provides molecular insights however at a high computational cost. The integration of DFT with MD shows promise in predicting PFAS behavior in different environments. This work summarizes reported studies on PFAS compounds, focusing on adsorption, destruction, and bioaccumulation, highlighting contributions of computational methods while discussing the need for continued research. The findings emphasize the importance of computational chemistry in addressing PFAS contamination, guiding risk assessments, and informing future research and innovations in this field.
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Affiliation(s)
- Bruno Bezerra de Souza
- John A. Reif, Jr. Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Jay Meegoda
- John A. Reif, Jr. Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA.
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6
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Zhao Y, Koster van Groos PG, Thakur N, Fuller ME, Soto A, Hatzinger PB. Formation of volatile chlorinated and brominated products during low temperature thermal decomposition of the representative PFAS perfluorohexane sulfonate (PFHxS) in the presence of NaCl and NaBr. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 348:123782. [PMID: 38484959 DOI: 10.1016/j.envpol.2024.123782] [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: 12/20/2023] [Revised: 02/26/2024] [Accepted: 03/11/2024] [Indexed: 04/07/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are synthetic organofluorine compounds known for their chemical and physical stability as well as their wide range of uses. Some PFAS are widely distributed in the environment, leading to concerns related to both environmental and human health. High temperature thermal treatment (i.e., incineration) has been utilized for PFAS treatment, but this requires significant infrastructure and energy, prompting interest in lower temperature approaches that may still lead to efficient destruction. Lower treatment temperatures, however, increase the potential for incomplete PFAS mineralization and formation of volatile organofluorine (VOF) products. Herein, we report the formation of novel VOF products that include chlorinated and brominated compounds during the thermal treatment of potassium perfluorohexane sulfonate (PFHxS), a representative perfluoroalkyl acid (PFAA). By comparing the gas chromatography-mass spectrometry (GC-MS) results of known VOF stocks to evolved VOF during thermal treatment of PFAS, the formation of perfluorohexyl chloride and perfluorohexyl bromide was observed when PFHxS was heated at temperatures between 275 and 475 °C in the presence of NaCl and NaBr, respectively. To our knowledge, this is the first report of chlorinated or brominated VOF products during thermal treatment of a PFAA. These findings suggest that a range of mixed halogenated VOF may form during thermal treatment of PFAS at relatively low temperature (e.g., 500 °C) and that these can be a function of salts present in the matrix.
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Affiliation(s)
- Yuwei Zhao
- Biotechnology Development and Applications Group, APTIM, 17 Princess Rd. Lawrenceville, NJ, 08648, USA.
| | - Paul G Koster van Groos
- Biotechnology Development and Applications Group, APTIM, 17 Princess Rd. Lawrenceville, NJ, 08648, USA
| | - Nikita Thakur
- Biotechnology Development and Applications Group, APTIM, 17 Princess Rd. Lawrenceville, NJ, 08648, USA
| | - Mark E Fuller
- Biotechnology Development and Applications Group, APTIM, 17 Princess Rd. Lawrenceville, NJ, 08648, USA
| | - Anthony Soto
- Biotechnology Development and Applications Group, APTIM, 17 Princess Rd. Lawrenceville, NJ, 08648, USA
| | - Paul B Hatzinger
- Biotechnology Development and Applications Group, APTIM, 17 Princess Rd. Lawrenceville, NJ, 08648, USA
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7
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Winchell LJ, Wells MJM, Ross JJ, Kakar F, Teymouri A, Gonzalez DJ, Dangtran K, Bessler SM, Carlson S, Almansa XF, Norton JW, Bell KY. Fate of perfluoroalkyl and polyfluoroalkyl substances (PFAS) through two full-scale wastewater sludge incinerators. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2024; 96:e11009. [PMID: 38444297 DOI: 10.1002/wer.11009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 12/15/2023] [Accepted: 02/07/2024] [Indexed: 03/07/2024]
Abstract
Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are an emerging issue in wastewater treatment. High-temperature thermal processes, incineration being time-tested, offer the opportunity to destroy and change the composition of PFAS. The fate of PFAS has been documented through wastewater sludge incinerators, including a multiple hearth furnace (MHF) and a fluidized bed furnace (FBF). The dewatered wastewater sludge feedstock averaged 247- and 1280-μmol targeted PFAS per sample run in MHF and FBF feed, respectively. Stack emissions (reportable for all targeted PFAS from MHF only) averaged 5% of that value with shorter alkyl chain compounds comprising the majority of the targeted PFAS. Wet scrubber water streams accumulated nonpolar fluorinated organics from the furnace exhaust with an average of 0.740- and 0.114-mol F- per sample run, for the MHF and FBF, respectively. Simple alkane PFAS measured at the stack represented 0.5%-4.5% of the total estimated facility greenhouse gas emissions. PRACTITIONER POINTS: The MHF emitted six short chain PFAS from the stack, which were shorter alkyl chain compounds compared with sludge PFAS. The FBF did not consistently emit reportable PFAS from the stack, but contamination complicated the assessment. Five percent of the MHF sludge molar PFAS load was reported in the stack. MHF and FBF wet scrubber water streams accumulated nonpolar fluorinated organics from the furnace exhaust. Ultra-short volatile alkane PFAS measured at the stack represented 0.5%-4.5% of the estimated facility greenhouse gas emissions.
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Affiliation(s)
| | | | - John J Ross
- Brown and Caldwell, Walnut Creek, California, USA
| | - Farokh Kakar
- Brown and Caldwell, Walnut Creek, California, USA
| | - Ali Teymouri
- Brown and Caldwell, Walnut Creek, California, USA
| | | | - Ky Dangtran
- Dangtran Combustion Consulting, Katy, Texas, USA
| | - Scott M Bessler
- Metropolitan Sewer District of Greater Cincinnati, Cincinnati, Ohio, USA
| | - Shane Carlson
- Metropolitan Sewer District of Greater Cincinnati, Cincinnati, Ohio, USA
| | - Xavier Fonoll Almansa
- Great Lakes Water Authority, Detroit, Michigan, USA
- Maseeh Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas, USA
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8
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Mattila JM, Krug JD, Roberson WR, Burnette RP, McDonald S, Virtaranta L, Offenberg JH, Linak WP. Characterizing Volatile Emissions and Combustion Byproducts from Aqueous Film-Forming Foams Using Online Chemical Ionization Mass Spectrometry. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:3942-3952. [PMID: 38350647 PMCID: PMC10985785 DOI: 10.1021/acs.est.3c09255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
Aqueous film-forming foams (AFFFs) are used in firefighting applications and often contain per- and polyfluoroalkyl substances (PFAS), which can detrimentally impact environmental and biological health. Incineration is a potential disposal method for AFFFs, which may produce secondary PFAS and other air pollutants. We used online chemical ionization mass spectrometry (CIMS) to measure volatile PFAS emissions from incinerating AFFF concentrate solutions. We quantified perfluorinated carboxylic acids (PFCAs) during the incineration of legacy and contemporary AFFFs. These included trifluoroacetic acid, which reached mg m-3 quantities in the incinerator exhaust. These PFCAs likely arose as products of incomplete combustion of AFFF fluorosurfactants with lower peak furnace temperatures yielding higher PFCA concentrations. We also detected other short-chain PFAS, and other novel chemical products in AFFF combustion emissions. The volatile headspace above AFFF solutions contained larger (C ≥ 8), less oxidized PFAS detected by CIMS. We identified neutral PFAS resembling fluorotelomer surfactants (e.g., fluorotelomer sulfonamide alkylbetaines and fluorotelomer thioether amido sulfonates) and fluorotelomer alcohols in contemporary AFFF headspaces. Directly comparing the distinct chemical spaces of AFFF volatile headspace and combustion byproducts as measured by CIMS provides insight toward the chemistry of PFAS during thermal treatment of AFFFs.
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Affiliation(s)
- James M. Mattila
- Oak Ridge Institute for Science and Education, Office of Research and Development, U.S. Environmental Protection Agency, Durham, North Carolina 27709, United States
| | - Jonathan D. Krug
- Center for Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Durham, North Carolina 27709, United States
| | - William R. Roberson
- Center for Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Durham, North Carolina 27709, United States
| | | | - Stella McDonald
- Jacobs Technology Inc., Cary, North Carolina 27518, United States
| | - Larry Virtaranta
- Center for Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Durham, North Carolina 27709, United States
| | - John H. Offenberg
- Center for Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Durham, North Carolina 27709, United States
| | - William P. Linak
- Center for Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Durham, North Carolina 27709, United States
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9
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Chu C, Ma LL, Alawi H, Ma W, Zhu Y, Sun J, Lu Y, Xue Y, Chen G. Mechanistic exploration of polytetrafluoroethylene thermal plasma gasification through multiscale simulation coupled with experimental validation. Nat Commun 2024; 15:1654. [PMID: 38395949 PMCID: PMC10891128 DOI: 10.1038/s41467-024-45077-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 01/15/2024] [Indexed: 02/25/2024] Open
Abstract
The ever-growing quantities of persistent Polytetrafluoroethylene (PTFE) wastes, along with consequential ecological and human health concerns, stimulate the need for alternative PTFE disposal method. The central research challenge lies in elucidating the decomposition mechanism of PTFE during high-temperature waste treatment. Here, we propose the PTFE microscopic thermal decomposition pathways by integrating plasma gasification experiments with multi-scale simulations strategies. Molecular dynamic simulations reveal a pyrolysis-oxidation & chain-shortening-deep defluorination (POCD) degradation pathway in an oxygen atmosphere, and an F abstraction-hydrolysis-deep defluorination (FHD) pathway in a steam atmosphere. Density functional theory computations demonstrate the vital roles of 1O2 and ·H radicals in the scission of PTFE carbon skeleton, validating the proposed pathways. Experimental results confirm the simulation results and show that up to 80.12% of gaseous fluorine can be recovered through plasma gasification within 5 min, under the optimized operating conditions determined through response surface methodology.
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Affiliation(s)
- Chu Chu
- School of Environmental Science and Engineering, Tianjin University/Tianjin Key Lab of Biomass/Wastes Utilization, Tianjin, 300072, China
| | - Long Long Ma
- School of Energy &Environment, Key Lab Energy Thermal Conversion & Control, Southeast University, Nanjing, 210096, China
| | - Hyder Alawi
- School of Environmental Science and Engineering, Tianjin University/Tianjin Key Lab of Biomass/Wastes Utilization, Tianjin, 300072, China
| | - Wenchao Ma
- School of Environmental Science and Engineering, Tianjin University/Tianjin Key Lab of Biomass/Wastes Utilization, Tianjin, 300072, China.
| | - YiFei Zhu
- School of Electrical Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Junhao Sun
- Postdoctoral Programme, Guosen Securities, Shenzhen, 518001, China
| | - Yao Lu
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin, 300401, China
| | - Yixian Xue
- School of Environmental Science and Engineering, Tianjin University/Tianjin Key Lab of Biomass/Wastes Utilization, Tianjin, 300072, China
| | - Guanyi Chen
- School of Environmental Science and Engineering, Tianjin University/Tianjin Key Lab of Biomass/Wastes Utilization, Tianjin, 300072, China
- School of Ecology and Environment, Tibet University, Lhasa, 850012, Tibet, China
- School of Mechanical Engineering, Tianjin University of Commerce, Tianjin, 300314, China
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10
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Ram H, Sadej TP, Murphy CC, Mallo TJ, Westmoreland PR. Thermochemistry of Species in Gas-Phase Thermal Oxidation of C 2 to C 8 Perfluorinated Carboxylic Acids. J Phys Chem A 2024; 128:1313-1326. [PMID: 38335280 DOI: 10.1021/acs.jpca.3c06937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
New thermochemical properties, Cp°(T), H°(T), S°(T), and G°(T), are predicted for 123 species involved in the thermal destruction of perfluorinated carboxylic acids (PFCAs) using computational quantum chemistry and ideal-gas statistical mechanics. Relevant species were identified from the development of mechanisms for the pyrolysis and oxidation of PFCAs of C2 to C8 in length. Partition functions were obtained from the results of calculations at the G4 level for species up to C4 in length and M06-2X-D3(0)/def2-QZVPP for species C5 to C8 in length. The 1D hindered-rotor approximation was used to correct for torsional modes in the larger species. Ideal-gas thermochemistry was computed and fitted to 7-parameter NASA polynomials over a 200-2500 K temperature range, and the data are provided in standardized format. To gauge the effects of both method and basis set choice, enthalpies of formation at 0 K are calculated from various other density functionals (including B3LYP and ωB97XD), basis sets, and composite model chemistries (CBS-QB3). They are benchmarked against data from the Active Thermochemical Tables, high-level ANL0 calculations from the literature, and G4 calculations from this work. The effects of internal rotations and other anharmonicities are discussed, and bond dissociation energies and reaction equilibria provide mechanistic insights.
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Affiliation(s)
- Hrishikesh Ram
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27606, United States
| | - Thomas P Sadej
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27606, United States
| | - C Claire Murphy
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27606, United States
| | - Tim J Mallo
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27606, United States
| | - Phillip R Westmoreland
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27606, United States
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11
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Al-Kwradi M, Ali L, Altarawneh M. Predicting the Decomposition Mechanism of the Serine α-Amino Acid in the Gas Phase and Condensed Media. ACS OMEGA 2024; 9:8574-8584. [PMID: 38405454 PMCID: PMC10882666 DOI: 10.1021/acsomega.3c10496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/16/2024] [Accepted: 01/22/2024] [Indexed: 02/27/2024]
Abstract
Comprehending the nitrogen combustion chemistry during the thermal treatment of biomass demands acquiring a detailed mechanism for reaction pathways that dictate the degradation of amino acids. Serine (Ser) is an important α-amino acid that invariably exists in various categories of biomass, most notably algae. Based on density functional theory (DFT) coupled with kinetic modeling, this study presents a mechanistic overview of reactions that govern the fragmentation of the Ser compound in the gas phase as well as in the crystalline form. Thermokinetic parameters are computed for a large set of reactions and involved species. The initial decomposition of Ser is solely controlled by a dehydration channel that leads to the formation of a 2-aminoacrylic acid molecule. Decarboxylation and deamination routes are likely to be of negligible importance. The falloff window of the dehydration channel extends until the atmospheric pressure. Bimolecular reactions between two Ser compounds simulate the widely discussed cross-linking reactions that prevail in the condensed medium. It is demonstrated that the formation of the key experimentally observed products (NH3, CO2, and CO) may originate from direct bond fissions in the melted phase of Ser prior to evaporation. A constructed kinetic model (with 24 reactions) accounts for the primary steps in the degradation of the Ser molecule in the gas phase. These steps include dehydration, decarboxylation, deamination, and others. The kinetic model presents an onset decomposition temperature of 700 K with the complete conversion attained at ∼1090 K. Likewise, the model portrays the temperature-dependent increasing yields of CO2 and NH3. The results presented in this work offer a detailed analysis of the intricate chemical processes involved in nitrogen transformations, specifically in relation to amino acids. Amino acids play a crucial role as the primary nitrogen carriers in biomass, such as microalgae and protein-rich biomass.
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Affiliation(s)
- Mubarak Al-Kwradi
- Department of Chemical and Petroleum Engineering, United Arab Emirates University,, Sheikh Khalifa bin Zayed Street, Al-Ain 15551, United Arab Emirates
| | - Labeeb Ali
- Department of Chemical and Petroleum Engineering, United Arab Emirates University,, Sheikh Khalifa bin Zayed Street, Al-Ain 15551, United Arab Emirates
| | - Mohammednoor Altarawneh
- Department of Chemical and Petroleum Engineering, United Arab Emirates University,, Sheikh Khalifa bin Zayed Street, Al-Ain 15551, United Arab Emirates
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12
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Kim Y, Pike KA, Gray R, Sprankle JW, Faust JA, Edmiston PL. Non-targeted identification and semi-quantitation of emerging per- and polyfluoroalkyl substances (PFAS) in US rainwater. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:1771-1787. [PMID: 36341487 DOI: 10.1039/d2em00349j] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
High-resolution mass spectrometry was used to screen for emerging per- and polyfluorinated alkyl substances (PFAS) in precipitation samples collected in summer 2019 at seven sites in the United States. We previously quantified the concentration of ten PFAS in the rainwater samples using the method of isotopic dilution (Pike et al., 2021). Nine of these targeted analytes belonged to the U.S. Environmental Protection Agency Regional Screening Level list, herein referred to as EPA-monitored analytes. In this new work, we identify emerging PFAS compounds by liquid chromatography quadrupole time-of-flight mass spectrometry. Several emerging PFAS were detected across all samples, with the most prevalent compounds being C3-C8 hydrogen-substituted perfluorocarboxylic acids (H-PFCAs) and fluorotelomer carboxylic acids (FTCAs). Concentrations of emerging PFAS were in the 10-1000 ng L-1 range (approximately 1-2 orders of magnitude greater than EPA-monitored PFAS) at all sites except Wooster, OH, where concentrations were even higher, with a maximum estimated ΣPFAS of 16 400 ng L-1. The elevated levels of emerging PFAS in the Wooster samples were predominantly even and odd chain-length H-PFCAs and FTCAs comprised of complex mixtures of branched isomers. This unique composition did not match any known manufactured PFAS formulation reported to date, but it could represent thermally transformed by-products emitted by a local point source. Overall, the results indicate that PFAS outside of the standard analyte lists make up a significant and previously unappreciated fraction of contaminants in rainwater collected within the central U.S.-and potentially world-wide-especially in proximity to localized point sources.
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Affiliation(s)
- Yubin Kim
- Department of Chemistry, College of Wooster, Wooster, OH, USA.
| | - Kyndal A Pike
- Department of Chemistry, College of Wooster, Wooster, OH, USA.
- Department of Mathematical & Computational Sciences, College of Wooster, Wooster, OH, USA
| | - Rebekah Gray
- Department of Chemistry, College of Wooster, Wooster, OH, USA.
| | - Jameson W Sprankle
- Department of Chemistry, College of Wooster, Wooster, OH, USA.
- Department of Earth Sciences, College of Wooster, Wooster, OH, USA
| | | | - Paul L Edmiston
- Department of Chemistry, College of Wooster, Wooster, OH, USA.
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13
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Wallace JS, Edirisinghe D, Seyedi S, Noteboom H, Blate M, Balci DD, Abu-Orf M, Sharp R, Brown J, Aga DS. Burning questions: Current practices and critical gaps in evaluating removal of per- and polyfluoroalkyl substances (PFAS) during pyrolysis treatments of biosolids. JOURNAL OF HAZARDOUS MATERIALS LETTERS 2023; 4:100079. [PMID: 37790729 PMCID: PMC10545407 DOI: 10.1016/j.hazl.2023.100079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Concerns surrounding potential health and environmental impacts of per- and polyfluoroalkyl substances (PFAS) are growing at tremendous rates because adverse health impacts are expected with trace-level exposures. Extreme measures are required to mitigate potential PFAS contamination and minimize exposures. Extensive PFAS use results in the release of diverse PFAS species from domestic, industrial, and municipal effluents to wastewater, which partition to biosolids throughout secondary treatment. Biosolids generated during municipal wastewater treatment are a major environmental source of PFAS due to prevailing disposal practices as fertilizers. Pyrolysis is emerging as a viable, scalable technology for PFAS removal from biosolids while retaining nutrients and generating renewable, raw materials for energy generation. Despite early successes of pyrolysis in PFAS removal, significant unknowns remain about PFAS and transformation product fates in pyrolysis products and emissions. Applicable PFAS sampling methods, analytical workflows, and removal assessments are currently limited to a subset of high-interest analytes and matrices. Further, analysis of exhaust gases, particulate matter, fly ashes, and other pyrolysis end-products remain largely unreported or limited due to cost and sampling limitations. This paper identifies critical knowledge gaps on the pyrolysis of biosolids that must be addressed to assess the effectiveness of PFAS removal during pyrolysis treatment.
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Affiliation(s)
- Joshua S. Wallace
- Department of Chemistry, University at Buffalo – The State University of New York, Buffalo, NY 14260, USA
- RENEW Institute, University at Buffalo – The State University of New York, Buffalo, NY 14260, USA
| | - Dulan Edirisinghe
- Department of Chemistry, University at Buffalo – The State University of New York, Buffalo, NY 14260, USA
| | - Saba Seyedi
- Hazen and Sawyer, 498 Seventh Avenue, 11th Floor, New York, NY 10018, USA
| | - Haley Noteboom
- Hazen and Sawyer, 498 Seventh Avenue, 11th Floor, New York, NY 10018, USA
| | - Micah Blate
- Hazen and Sawyer, 498 Seventh Avenue, 11th Floor, New York, NY 10018, USA
| | - Derya Dursun Balci
- Hazen and Sawyer, 498 Seventh Avenue, 11th Floor, New York, NY 10018, USA
| | - Mohammad Abu-Orf
- Hazen and Sawyer, 498 Seventh Avenue, 11th Floor, New York, NY 10018, USA
| | - Robert Sharp
- Hazen and Sawyer, 498 Seventh Avenue, 11th Floor, New York, NY 10018, USA
- Civil & Environmental Engineering, Manhattan College, Riverdale, NY 10471, USA
| | - Jeanette Brown
- Civil & Environmental Engineering, Manhattan College, Riverdale, NY 10471, USA
| | - Diana S. Aga
- Department of Chemistry, University at Buffalo – The State University of New York, Buffalo, NY 14260, USA
- RENEW Institute, University at Buffalo – The State University of New York, Buffalo, NY 14260, USA
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14
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Bezerra de Souza B, Aluthgun Hewage S, A Kewalramani J, Ct van Duin A, N Meegoda J. A ReaxFF-based molecular dynamics study of the destruction of PFAS due to ultrasound. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 333:122026. [PMID: 37315883 DOI: 10.1016/j.envpol.2023.122026] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 06/05/2023] [Accepted: 06/10/2023] [Indexed: 06/16/2023]
Abstract
This work uses a computational approach to provide a mechanistic explanation for the experimentally observed destruction of per- and polyfluoroalkyl substances (PFAS) in water due to ultrasound. The PFAS compounds have caused a strong public and regulatory response due to their ubiquitous presence in the environment and toxicity to humans. In this research, ReaxFF -based Molecular Dynamics simulation under several temperatures ranging from 373 K to 5,000 K and different environments such as water vapor, O2, N2, and air were performed to understand the mechanism of PFAS destruction. The simulation results showed greater than 98% PFAS degradation was observed within 8 ns under a temperature of 5,000 K in a water vapor phase, replicating the observed micro/nano bubbles implosion and PFAS destruction during the application of ultrasound. Additionally, the manuscript discusses the reaction pathways and how PFAS degradation evolves providing a mechanistic basis for the destruction of PFAS in water due to ultrasound. The simulation showed that small chain molecules C1 and C2 fluoro-radical products are the most dominant species over the simulated period and are the impediment to an efficient degradation of PFAS. Furthermore, this research confirms the empirical findings observations that the mineralization of PFAS molecules occurs without the generation of byproducts. These findings highlight the potential of virtual experiments in complementing laboratory experiments and theoretical projections to enhance the understanding of PFAS mineralization during the application of ultrasound.
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Affiliation(s)
- Bruno Bezerra de Souza
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, USA
| | - Shaini Aluthgun Hewage
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, USA
| | - Jitendra A Kewalramani
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, USA
| | - Adri Ct van Duin
- Department of Mechanical Engineering, The Pennsylvania State University, State College, PA, USA
| | - Jay N Meegoda
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, USA.
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15
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Serna-Sanchez E, Pellizzeri S. Predicting pyrolysis decomposition of PFOA using computational nanoreactors: a thermodynamic study. RSC Adv 2023; 13:25699-25703. [PMID: 37655356 PMCID: PMC10466175 DOI: 10.1039/d3ra05187k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 08/17/2023] [Indexed: 09/02/2023] Open
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a large, complex, environmentally persistent, and ever-expanding group of manufactured chemicals. Disposal of these compounds could produce potentially dangerous products necessitating the need to quickly predict their decomposition products. This study focuses on the thermal decomposition of perfluorooctanoic acid (PFOA) using nanoreactor simulations to find the decomposition products and their respective energies. Applying the nanoreactor method, which is novel for this system, allows for rapid prediction of thermal decomposition pathways with minimal researcher bias and it predicted PFOA to decompose at ∼650 °C, consistent with previously reported experimental studies.
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Affiliation(s)
- Elizabeth Serna-Sanchez
- Department of Chemistry and Biochemistry, Eastern Illinois University 600 Lincoln Avenue Charleston IL 61920 USA
| | - Steven Pellizzeri
- Department of Chemistry and Biochemistry, Eastern Illinois University 600 Lincoln Avenue Charleston IL 61920 USA
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16
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Sørmo E, Castro G, Hubert M, Licul-Kucera V, Quintanilla M, Asimakopoulos AG, Cornelissen G, Arp HPH. The decomposition and emission factors of a wide range of PFAS in diverse, contaminated organic waste fractions undergoing dry pyrolysis. JOURNAL OF HAZARDOUS MATERIALS 2023; 454:131447. [PMID: 37121036 DOI: 10.1016/j.jhazmat.2023.131447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/23/2023] [Accepted: 04/17/2023] [Indexed: 05/19/2023]
Abstract
Current treatment options for organic waste contaminated with per- and polyfluoroalkyl substances (PFAS) are generally limited to incineration, composting or landfilling, all resulting in emissions. Dry pyrolysis is a promising emerging alternative to these practices, but there is uncertainty related to the fate of PFAS during this process. The present work first developed a robust method for the determination of PFAS in complex matrices, such as sewage sludge and biochar. Then, a mass balance was established for 56 different PFAS during full-scale pyrolysis (2-10 kg biochar hr-1, 500-800 °C) of sewage sludges, food waste reject, garden waste and waste timber. PFAS were found in all wastes (56-3651 ng g-1), but pyrolysis resulted in a ≥ 96.9% removal. Residual PFAS (0.1-3.4 ng g-1) were detected in biochars obtained at temperatures up to 750 °C and were dominated by long chain PFAS. Emitted PFAS loads ranged from 0.01 to 3.1 mg tonne-1 of biochar produced and were dominated by short chain PFAS. Emissions made up < 3% of total PFAS-mass in the wastes. Remaining uncertainties are mainly related to the presence of thermal degradation products in flue gas and condensation oils.
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Affiliation(s)
- Erlend Sørmo
- Geotechnics and Environment, Norwegian Geotechnical Institute (NGI), Oslo, Norway; Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences (NMBU), Ås, Norway.
| | - Gabriela Castro
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Michel Hubert
- Geotechnics and Environment, Norwegian Geotechnical Institute (NGI), Oslo, Norway; Faculty of Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Viktória Licul-Kucera
- Institute for Analytical Research, Hochschulen Fresenius gem. Trägesellschaft mbH, Idstein, Germany; Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, Netherlands
| | - Marjorie Quintanilla
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | | | - Gerard Cornelissen
- Geotechnics and Environment, Norwegian Geotechnical Institute (NGI), Oslo, Norway; Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Hans Peter H Arp
- Geotechnics and Environment, Norwegian Geotechnical Institute (NGI), Oslo, Norway; Department of Chemistry, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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17
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Moavenzadeh Ghaznavi S, Zimmerman C, Shea ME, MacRae JD, Peckenham JM, Noblet CL, Apul OG, Kopec AD. Management of per- and polyfluoroalkyl substances (PFAS)-laden wastewater sludge in Maine: Perspectives on a wicked problem. Biointerphases 2023; 18:041004. [PMID: 37602771 DOI: 10.1116/6.0002796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 07/21/2023] [Indexed: 08/22/2023] Open
Abstract
This article discusses the challenges and potential solutions for managing wastewater sludge that contains per- and polyfluoroalkyl substances (PFAS), using the experience in Maine as a guide toward addressing the issue nationally. Traditional wastewater treatment, designed to remove excess organic waste and nutrients, does not eliminate persistent toxic pollutants like PFAS, instead partitioning the chemicals between discharged effluent and the remaining solids in sludge. PFAS chemistry, the molecular size, the alkyl chain length, fluorine saturation, the charge of the head group, and the composition of the surrounding matrix influence PFAS partitioning between soil and water. Land application of sludge, incineration, and storage in a landfill are the traditional management options. Land application of Class B sludge on agricultural fields in Maine peaked in the 1990s, totaling over 2 × 106 cu yd over a 40-year period and has contaminated certain food crops and animal forage, posing a threat to the food supply and the environment. Additional Class A EQ (Exceptional Quality) composted sludge was also applied to Maine farmland. The State of Maine banned the land application of wastewater sludge in August 2022. Most sludge was sent to the state-owned Juniper Ridge Landfill, which accepted 94 270 tons of dewatered sludge in 2022, a 14% increase over 2019. Between 2019 and 2022, the sum of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) concentrations in sludge sent to the landfill ranged from 1.2 to 104.9 ng/g dw. In 2022, the landfill generated 71.6 × 106 l of leachate. The concentration of sum of six PFAS in the leachate increased sixfold between 2021 and 2022, reaching 2 441 ng/l. The retention of PFAS within solid-waste landfills and the potential for long-term release of PFAS through liners into groundwater require ongoing monitoring. Thermal treatment, incineration, or pyrolysis can theoretically mineralize PFAS at high temperatures, yet the strong C-F bond and reactivity of fluorine require extreme temperatures for complete mineralization. Future alternatives may include interim options such as preconditioning PFAS with nonpolar solvents prior to immobilization in landfills, removing PFAS from leachate, and interrupting the cycle of PFAS moving from landfill, via leachate, to wastewater treatment, and then back to the landfill via sludge. Long-term solutions may involve destructive technologies such as electron beam irradiation, electrochemical advanced oxidation, or hydrothermal liquefaction. The article highlights the need for innovative and sustainable solutions for managing PFAS-contaminated wastewater sludge.
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Affiliation(s)
- Simin Moavenzadeh Ghaznavi
- Department of Civil and Environmental Engineering, University of Maine, 5711 Boardman Hall, Orono, Maine 04473
| | - Charity Zimmerman
- School of Economics, University of Maine, 5782 Winslow Hall, Orono, Maine 04473
| | - Molly E Shea
- School of Economics, University of Maine, 5782 Winslow Hall, Orono, Maine 04473
| | - Jean D MacRae
- Department of Civil and Environmental Engineering, University of Maine, 5711 Boardman Hall, Orono, Maine 04473
| | - John M Peckenham
- Senator George J. Mitchell Center for Sustainability Solutions, University of Maine, 5710 Norman Smith Hall, Orono, Maine 04473
| | - Caroline L Noblet
- School of Economics, University of Maine, 5782 Winslow Hall, Orono, Maine 04473
| | - Onur G Apul
- Department of Civil and Environmental Engineering, University of Maine, 5711 Boardman Hall, Orono, Maine 04473
| | - A Dianne Kopec
- Senator George J. Mitchell Center for Sustainability Solutions, University of Maine, 5710 Norman Smith Hall, Orono, Maine 04473
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18
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Kumar R, Dada TK, Whelan A, Cannon P, Sheehan M, Reeves L, Antunes E. Microbial and thermal treatment techniques for degradation of PFAS in biosolids: A focus on degradation mechanisms and pathways. JOURNAL OF HAZARDOUS MATERIALS 2023; 452:131212. [PMID: 36934630 DOI: 10.1016/j.jhazmat.2023.131212] [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: 02/02/2023] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 05/03/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are persistent organic chemicals detected in biosolids worldwide, which have become a significant concern for biosolids applications due to their increasing environmental risks. Hence, it is pivotal to understand the magnitude of PFAS contamination in biosolids and implement effective technologies to reduce their contamination and prevent hazardous aftermaths. Thermal techniques such as pyrolysis, incineration and gasification, and biodegradation have been regarded as impactful solutions to degrade PFAS and transform biosolids into value-added products like biochar. These techniques can mineralize PFAS compounds under specific operating parameters, which can lead to unique degradation mechanisms and pathways. Understanding PFAS degradation mechanisms can pave the way to design the technology and to optimize the process conditions. Therefore, in this review, we aim to review and compare PFAS degradation mechanisms in thermal treatment like pyrolysis, incineration, gasification, smouldering combustion, hydrothermal liquefaction (HTL), and biodegradation. For instance, in biodegradation of perfluorooctane sulfonic acid (PFOS), firstly C-S bond cleavage occurs which is followed by hydroxylation, decarboxylation and defluorination reactions to form perfluoroheptanoic acid. In HTL, PFOS degradation is carried through OH-catalyzed series of nucleophilic substitution and decarboxylation reactions. In contrast, thermal PFOS degradation involves a three-step random-chain scission pathway. The first step includes C-S bond cleavage, followed by defluorination of perfluoroalkyl radical, and radical chain propagation reactions. Finally, the termination of chain propagation reactions produces very short-fluorinated units. We also highlighted important policies and strategies employed worldwide to curb PFAS contamination in biosolids.
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Affiliation(s)
- Ravinder Kumar
- College of Science & Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Tewodros Kassa Dada
- College of Science & Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Anna Whelan
- College of Science & Engineering, James Cook University, Townsville, QLD 4811, Australia; Townsville City Council, Wastewater Operations, Townsville, QLD 4810, Australia
| | | | - Madoc Sheehan
- College of Science & Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Louise Reeves
- Queensland Water Directorate, Brisbane, QLD 4009, Australia
| | - Elsa Antunes
- College of Science & Engineering, James Cook University, Townsville, QLD 4811, Australia.
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19
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Wang J, Song M, Abusallout I, Hanigan D. Thermal Decomposition of Two Gaseous Perfluorocarboxylic Acids: Products and Mechanisms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:6179-6187. [PMID: 37018767 DOI: 10.1021/acs.est.2c08210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The thermal decomposition products and mechanisms of per- and polyfluoroalkyl substances (PFASs) are poorly understood despite the use of thermal treatment to remediate PFAS-contaminated media. To identify the thermal decomposition products and mechanisms of perfluorocarboxylic acids (PFCAs), gaseous perfluoropropionic acid (PFPrA) and perfluorobutyric acid (PFBA) were decomposed in nitrogen and oxygen at temperatures from 200 to 780 °C. In nitrogen (i.e., pyrolysis), the primary products of PFPrA were CF2═CF2, CF3CF2H, and CF3COF. CF3CF═CF2 was the dominant product of PFBA. These products are produced by HF elimination (detected as low as 200 °C). CF4 and C2F6 were observed from both PFCAs, suggesting formation of perfluorocarbon radical intermediates. Pyrolysis products were highly thermally stable, resulting in poor defluorination. In oxygen (i.e., combustion), the primary product of both PFPrA and PFBA below 400 °C was COF2, but the primary product was SiF4 above 600 °C due to reactions with the quartz reactor. Oxygen facilitated thermal defluorination by reacting with PFCAs and with pyrolysis products (i.e., fluoroolefins and fluorocarbon radicals). Platinum improved combustion of PFCAs to COF2 at temperatures as low as 200 °C, while quartz promoted the combustion of PFCAs into SiF4 at higher temperatures (>600 °C), highlighting the importance of surface reactions that are not typically incorporated into computational approaches.
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Affiliation(s)
- Junli Wang
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Nevada 89557-0258, United States
- Department of Environmental Science, University of California, Riverside, California 92521, United States
| | - Mingrui Song
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Nevada 89557-0258, United States
| | - Ibrahim Abusallout
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Nevada 89557-0258, United States
- CDM Smith, 75 State Street, Suite 701, Boston, Massachusetts 02109, United States
- Fraunhofer USA, Inc., Center Midwest, Division for Coatings and Diamonds Technologies, East Lansing, Michigan 48824, United States
| | - David Hanigan
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Nevada 89557-0258, United States
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20
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Chen Y, Zhang H, Liu Y, Bowden JA, Tolaymat TM, Townsend TG, Solo-Gabriele HM. Evaluation of per- and polyfluoroalkyl substances (PFAS) in leachate, gas condensate, stormwater and groundwater at landfills. CHEMOSPHERE 2023; 318:137903. [PMID: 36669537 PMCID: PMC10536789 DOI: 10.1016/j.chemosphere.2023.137903] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 01/15/2023] [Accepted: 01/16/2023] [Indexed: 06/17/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS), found in many consumer products, are commonly disposed of in landfills at the end of their service lives. To identify landfill liquids that should be prioritized for treatment, this study aimed to evaluate PFAS levels in different aqueous samples from landfills and identify relationships between PFAS and landfill characteristics. Twenty-six PFAS including 11 perfluoroalkyl carboxylic acids (PFCAs), 7 perfluoroalkyl sulfonates (PFSAs), and 8 perfluoroalkyl acid precursors (PFAA-precursors) were measured in municipal solid waste (MSW) leachate, construction and demolition debris (CDD) leachate, municipal solid waste incineration (MSWI) ash leachate, gas condensate, stormwater, and groundwater from landfills. Based on the median, results show that PFAS levels in MSW leachate were the highest (10,000 ng L-1), CDD leachate were intermediate (6200 ng L-1), and MSWI ash leachate were the lowest (1300 ng L-1) among the leachates evaluated. PFAS levels in gas condensate (7000 ng L-1) were similar to MSW leachate. PFAS in stormwater and groundwater were low (medians were less than 500 ng L-1). Dominant subgroups included PFCAs and PFAA-precursors in all leachates. PFSAs were also found in CDD leachate, PFAA-precursors in gas condensate, and PFCAs in stormwater and groundwater. Landfill characteristics significantly correlated with ∑26PFAS included waste proportions (percentage of MSWI ash in landfill, |rs| = 0.22), operational status (active or not, |rs| = 0.27) and rainfall (30-d cumulative rainfall, |rs| = 0.39). The results from this study can be used to prioritize which landfills and which reservoir of liquids (and corresponding subgroup of PFAS) to target for PFAS management.
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Affiliation(s)
- Yutao Chen
- Department of Civil, Architectural, and Environmental Engineering, College of Engineering, University of Miami, Coral Gables, Florida 33146, United States
| | - Hekai Zhang
- Department of Civil, Architectural, and Environmental Engineering, College of Engineering, University of Miami, Coral Gables, Florida 33146, United States
| | - Yalan Liu
- Department of Environmental Engineering Sciences, College of Engineering, University of Florida, Gainesville, FL 32611, United States
| | - John A Bowden
- Department of Environmental Engineering Sciences, College of Engineering, University of Florida, Gainesville, FL 32611, United States; Center for Environmental and Human Toxicology & Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, United States
| | - Thabet M Tolaymat
- Center for Environmental Solutions and Emergency Response, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH 45268, United States
| | - Timothy G Townsend
- Department of Environmental Engineering Sciences, College of Engineering, University of Florida, Gainesville, FL 32611, United States
| | - Helena M Solo-Gabriele
- Department of Civil, Architectural, and Environmental Engineering, College of Engineering, University of Miami, Coral Gables, Florida 33146, United States.
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21
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Sharma S, Abeywardane K, Goldsmith CF. Theory-Based Mechanism for Fluoromethane Combustion I: Thermochemistry and Abstraction Reactions. J Phys Chem A 2023; 127:1499-1511. [PMID: 36745864 DOI: 10.1021/acs.jpca.2c06623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A new detailed chemical kinetic mechanism is presented for small fluorinated hydrocarbons. Ab initio electronic structure theory is used to provide heats of formation with subchemical accuracy. The ANL0 method is extended to include fluorine. The resulting heats of formation at 0 K are in excellent agreement with 36 benchmark species in the Active Thermochemical Tables, with a mean error of μ = -0.02 kJ/mol and a standard deviation of σ = 0.91 kJ/mol. The thermophysical properties for 92 small-molecule H/C/O/F species are computed. The rate coefficients for 40+ H-abstraction reactions involving H, O, F, OH, OF, HO2, and various methyl radicals with CH4, CH3F, CH2F2, CHF3, CH2O, and CHFO are discussed. The computed rate constants are in excellent agreement with the available literature. Additionally, 30+ rate constants are provided for F abstraction, which are several orders of magnitude smaller than H abstraction. The thermophysical properties and rate constants are provided in a mechanism. This mechanism is the first in a series of theory-based investigations into the thermal destruction of per- and polyfluorinated species.
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Affiliation(s)
- Siddha Sharma
- Chemical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Kento Abeywardane
- Chemical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - C Franklin Goldsmith
- Chemical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, United States
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22
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Adi MA, Altarawneh M. Formation of perfluorocarboxylic acids (PFCAs) from thermolysis of Teflon model compound. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:21360-21367. [PMID: 36266595 DOI: 10.1007/s11356-022-23714-1] [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: 03/15/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023]
Abstract
It has been widely postulated that thermal degradation of polytetrafluoroethylene (PTFE; commercially known as Teflon) under the presence of moisture presents a likely source for the formation of the notorious perfluorocarboxylic acids (CF3(CF2)nCO(OH) PFCAs) and perfluorinated aldehydes (CF3(CF2)nCO(F/H). Thus, deployment of objects laden with Teflon at the peak of their thermal stability may contribute to the atmospheric budget of PFCAs. However, the underlying mechanism remains largely speculative. This study reports potential energy surfaces for reactions that govern oxidative transformation of n-C8F18 (as a model compound of PTFE) into tridecafluoroheptanoyl fluoride and perfluoroheptanoic acid. Central to computed pathways are dissociative addition reactions of water over the carbonyl group and elimination of hydroperoxyl radicals. Facile activation enthalpies are encountered in the involved steps. Our analysis discloses that formation of the building monomer C2F4 should be suppressed under thermolysis oxidation conditions at which synthesis of trifluoroacetic acids is preferred. Constructed kinetic model illustrates a near-complete conversion of the PTFE model compound into perfluorocarboxylic acids (CF3(CF2)nCO(OH) and perfluorinated aldehydes. Outcomes from this study should be instrumental in providing a better understanding of the likely contribution of fluoropolymers in the observed environmental loads of perfluorocarboxylic acids.
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Affiliation(s)
- Maissa A Adi
- Department of Chemical and Petroleum Engineering, United Arab Emirates University, PO Box 15551, Al-Ain, United Arab Emirates
| | - Mohammednoor Altarawneh
- Department of Chemical and Petroleum Engineering, United Arab Emirates University, PO Box 15551, Al-Ain, United Arab Emirates.
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23
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Pinkard BR, Austin C, Purohit AL, Li J, Novosselov IV. Destruction of PFAS in AFFF-impacted fire training pit water, with a continuous hydrothermal alkaline treatment reactor. CHEMOSPHERE 2023; 314:137681. [PMID: 36584826 DOI: 10.1016/j.chemosphere.2022.137681] [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: 10/18/2022] [Revised: 12/24/2022] [Accepted: 12/26/2022] [Indexed: 06/17/2023]
Abstract
As regulations are being established to limit the levels of per- and polyfluoroalkyl substances (PFAS) in drinking water and wastewater, effective treatment technologies are needed to remove or destroy PFAS in contaminated liquid matrices. Many military installations and airports have fire training ponds (FTPs) where PFAS-containing firefighting foams are discharged during training drills. FTP water disposal is expensive and challenging due to the high PFAS levels. Hydrothermal alkaline treatment (HALT) has previously been shown to destroy a wide range of PFAS compounds with a high degree of destruction and defluorination. In this study, we investigate the performance of a continuous flow HALT reactor for destroying PFAS in contaminated FTP water samples. Processing with 5 M-NaOH and 1.6 min of continuous processing results in >99% total PFAS destruction, and 10 min processing time yields >99% destruction of every measured PFAS species. Operating with 0.1 M-NaOH or 1 M-NaOH shows little effect on the destruction of measured perfluorosulfonic acids, while all measured perfluorocarboxylic acids and fluorotelomer sulfonates are reduced to levels below the method detection limits. Continuous HALT processing with sufficient NaOH loading appears to destroy parent PFAS compounds significantly faster than batch HALT processing, a positive indicator for scaling up HALT technology for practical applications in environmental site remediation activities.
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Affiliation(s)
- Brian R Pinkard
- Aquagga, Inc., Tacoma, WA, 98402, USA; University of Washington, Mechanical Engineering Department, Seattle, WA, 98195, USA.
| | - Conrad Austin
- University of Washington, Mechanical Engineering Department, Seattle, WA, 98195, USA.
| | - Anmol L Purohit
- University of Washington, Mechanical Engineering Department, Seattle, WA, 98195, USA
| | - Jianna Li
- University of Washington, Mechanical Engineering Department, Seattle, WA, 98195, USA; Key Laboratory of Thermo-Fluid Science and Engineering of MOE, School of Energy and Power Engineering, Xi'an Jiaotong University, 28 Xianning West Road, Xi'an, 710049, China
| | - Igor V Novosselov
- University of Washington, Mechanical Engineering Department, Seattle, WA, 98195, USA
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24
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Zhang J, Gao L, Bergmann D, Bulatovic T, Surapaneni A, Gray S. Review of influence of critical operation conditions on by-product/intermediate formation during thermal destruction of PFAS in solid/biosolids. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 854:158796. [PMID: 36115408 DOI: 10.1016/j.scitotenv.2022.158796] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 09/11/2022] [Accepted: 09/12/2022] [Indexed: 06/15/2023]
Abstract
Poly- and perfluoroalkyl substances (PFAS) are a large group of synthetic organofluorine compounds. Over 4700 PFAS compounds have been produced and used in our daily life since the 1940s. PFAS have received considerable interest because of their toxicity, environmental persistence, bioaccumulation and wide existence in the environment. Various treatment methods have been developed to overcome these issues. Thermal treatment such as combustion and pyrolysis/gasification have been employed to treat PFAS contaminated solids and soils. However, short-chain PFAS and/or volatile organic fluorine is produced and emitted via exhaust gas during the thermal treatment. Combustion can achieve complete mineralisation of PFAS at large scale operation using temperatures >1000 °C. Pyrolysis has been used in treatment of biosolids and has demonstrated that it could remove PFAS completely from the generated biochar by evaporation and degradation. Although pyrolysis partially degrades PFAS to short-chain fluorine containing organics in the syngas, it could not efficiently mineralise PFAS. Combustion of PFAS containing syngas at 1000 °C can achieve complete mineralisation of PFAS. Furthermore, the by-product of mineralisation, HF, should also be monitored due to its low regulated atmospheric discharge values. Alkali scrubbing is normally required to lower the HF concentration in the exhaust gas to acceptable discharge concentrations.
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Affiliation(s)
- Jianhua Zhang
- Institute for Sustainable Industries and Liveable Cities, Victoria University, Melbourne, VIC 8001, Australia.
| | - Li Gao
- Institute for Sustainable Industries and Liveable Cities, Victoria University, Melbourne, VIC 8001, Australia; South East Water Corporation, PO Box 2268, Seaford, Victoria 3198, Australia
| | - David Bergmann
- South East Water Corporation, PO Box 2268, Seaford, Victoria 3198, Australia
| | - Tamara Bulatovic
- South East Water Corporation, PO Box 2268, Seaford, Victoria 3198, Australia
| | - Aravind Surapaneni
- South East Water Corporation, PO Box 2268, Seaford, Victoria 3198, Australia
| | - Stephen Gray
- Institute for Sustainable Industries and Liveable Cities, Victoria University, Melbourne, VIC 8001, Australia
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25
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Khan MY, Song J, Narimani M, da Silva G. Thermal decomposition mechanism and kinetics of perfluorooctanoic acid (PFOA) and other perfluorinated carboxylic acids: a theoretical study. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:2475-2487. [PMID: 36468420 DOI: 10.1039/d2em00259k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Perfluorinated carboxylic acids (PFCAs), particularly perfluorooctanoic acid (PFOA), are broadly used for chemical synthesis and as surfactants, but they pose a serious threat to humans and wildlife because of toxicity concerns, environmental stability, and tendency to bioaccumulate. PFCA waste is commercially treated in incinerators, however, their exact degradation mechanisms are still unknown. In the present work, we report the decomposition mechanism and kinetics of straight-chain PFCAs using quantum chemistry and reaction rate theory calculations. Degradation mechanisms and associated kinetic parameters are determined for the complete series of straight-chain PFCAs from perfluorononanoic acid (C8F17COOH, C9) to fluoroformic acid (FCOOH, C1). Our results show that PFCA decomposition follows an analogous mechanism to perfluorinated sulfonic acids, where HF elimination from the acid head group produces a three membered ring intermediate, in this case a perfluorinated α-lactone. These perfluorinated α-lactones are short-lived intermediates that readily degrade into perfluorinated acyl fluorides and CO, thus shortening the perfluorinated chain by one C atom. Because perfluorinated acyl fluorides are known to hydrolyse to PFCAs, repeated cycles of carboxylic acid decomposition followed by acyl fluoride hydrolysis provides a mechanism for the complete mineralization of PFCAs to HF, CO, CO2, COF2, and CF2 during thermal decomposition in the presence of water vapor. These results provide a theoretical basis for future detailed chemical kinetic studies of incineration reactors and will assist in their design and optimisation so as to more efficiently decompose PFCAs and related waste.
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Affiliation(s)
- M Yasir Khan
- Department of Chemical Engineering, University of Melbourne, Victoria 3010, Australia.
| | - Jiaou Song
- Department of Chemical Engineering, University of Melbourne, Victoria 3010, Australia.
| | - Milad Narimani
- Department of Chemical Engineering, University of Melbourne, Victoria 3010, Australia.
| | - Gabriel da Silva
- Department of Chemical Engineering, University of Melbourne, Victoria 3010, Australia.
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26
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Meegoda JN, Bezerra de Souza B, Casarini MM, Kewalramani JA. A Review of PFAS Destruction Technologies. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph192416397. [PMID: 36554276 PMCID: PMC9778349 DOI: 10.3390/ijerph192416397] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/19/2022] [Accepted: 12/02/2022] [Indexed: 05/13/2023]
Abstract
Per- and polyfluoroalkyl substances (PFASs) are a family of highly toxic emerging contaminants that have caught the attention of both the public and private sectors due to their adverse health impacts on society. The scientific community has been laboriously working on two fronts: (1) adapting already existing and effective technologies in destroying organic contaminants for PFAS remediation and (2) developing new technologies to remediate PFAS. A common characteristic in both areas is the separation/removal of PFASs from other contaminants or media, followed by destruction. The widely adopted separation technologies can remove PFASs from being in contact with humans; however, they remain in the environment and continue to pose health risks. On the other hand, the destructive technologies discussed here can effectively destroy PFAS compounds and fully address society's urgent need to remediate this harmful family of chemical compounds. This review reports and compare widely accepted as well as emerging PFAS destruction technologies. Some of the technologies presented in this review are still under development at the lab scale, while others have already been tested in the field.
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27
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Etz BD, Mifkovic M, Vyas S, Shukla MK. High-temperature decomposition chemistry of trimethylsiloxane surfactants, a potential Fluorine-Free replacement for fire suppression. CHEMOSPHERE 2022; 308:136351. [PMID: 36084830 DOI: 10.1016/j.chemosphere.2022.136351] [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: 06/21/2022] [Revised: 09/01/2022] [Accepted: 09/02/2022] [Indexed: 06/15/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) have become global environmental contaminants due to being notoriously difficult to degrade, and it has become increasingly important to employ suitable PFAS alternatives, especially in aqueous film-forming foams (AFFF). Trimethylsiloxane (TriSil) surfactants are potential fluorine-free replacements for PFAS in fire suppression technologies. Yet because these compounds may be more susceptible to high-temperature decomposition, it is necessary to assess the potential environmental impact of their thermal degradation products. Our study analyzes the high-temperature degradation of a truncated trimethylsiloxane (TriSil-1n) surfactant based on quantum mechanical methods. The degradation chemistry of TriSil-1n was studied through radical formation and propagation initiated from two prominent pathways (unimolecular and bimolecular reactions) at both 298 K and 1200 K, a relevant temperature in flames and thermal incinerators. Regardless of the pathway taken and temperature, all radical intermediates stemmed from the polyethylene glycol chain and primarily formed stable polydimethylsiloxanes (PDMS) and small organics such as ethylene, formaldehyde, and acetaldehyde, among other products. The major degradation products of TriSil-1n resulting from high-temperature thermal degradation as predicted by this study would be relatively less harmful to the environment compared to PFAS incineration/combustion products from previous research, supporting the replacement of PFAS with TriSil surfactants.
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Affiliation(s)
- Brian D Etz
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN, 37830, USA; Simetri, Inc., 7005 University Blvd, Winter Park, FL, 32792, USA
| | | | - Shubham Vyas
- Colorado School of Mines, Golden, CO, 80401, USA.
| | - Manoj K Shukla
- Environmental Laboratory, US Army Engineer Research and Development Center, 3909 Halls Ferry Road, Vicksburg, MS, 39180, USA.
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28
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Wiens JP, Miller TM, Ard SG, Viggiano AA, Shuman NS. Elementary Reactions Leading to Perfluoroalkyl Substance Degradation in an Ar +/e – Plasma. J Phys Chem A 2022; 126:9076-9086. [DOI: 10.1021/acs.jpca.2c04898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Justin P. Wiens
- Boston College Institute for Scientific Research, Boston, Massachusetts 02549, United States
| | - Thomas M. Miller
- Boston College Institute for Scientific Research, Boston, Massachusetts 02549, United States
| | - Shaun G. Ard
- Space Vehicles Directorate, Kirtland Air Force Base, Air Force Research Laboratory, Albuquerque, New Mexico 87117, United States
| | - Albert A. Viggiano
- Space Vehicles Directorate, Kirtland Air Force Base, Air Force Research Laboratory, Albuquerque, New Mexico 87117, United States
| | - Nicholas S. Shuman
- Space Vehicles Directorate, Kirtland Air Force Base, Air Force Research Laboratory, Albuquerque, New Mexico 87117, United States
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29
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Paultre CB, Mebel AM, O’Shea KE. Computational Study of the Gas-Phase Thermal Degradation of Perfluoroalkyl Carboxylic Acids. J Phys Chem A 2022; 126:8753-8760. [DOI: 10.1021/acs.jpca.2c06437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Claude-Bernard Paultre
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Kevin E. O’Shea
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
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30
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Novel Magnetic Elastic Phase-Change Nanodroplets as Dual Mode Contrast Agent for Ultrasound and Magnetic Resonance Imaging. Polymers (Basel) 2022; 14:polym14142915. [PMID: 35890691 PMCID: PMC9318938 DOI: 10.3390/polym14142915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 06/05/2022] [Accepted: 06/08/2022] [Indexed: 01/25/2023] Open
Abstract
Recently, dual-mode imaging systems merging magnetic resonance imaging (MRI) and ultrasound (US) have been developed. Designing a dual-mode contrast agent is complex due to different mechanisms of enhancement. Herein, we describe novel phase change nanodroplets (PCNDs) with perfluoropentane encapsulated in a pre-polyglycerol sebacate (pre-PGS) shell loaded with polyethylene glycol (PEG)-coated iron oxide nanoparticles as having a dual-mode contrast agent effect. Iron oxide nanoparticles were prepared via the chemical co-precipitation method and PCNDs were prepared via the solvent displacement technique. PCNDs showed excellent enhancement in the in vitro US much more than Sonovue® microbubbles. Furthermore, they caused a susceptibility effect resulting in a reduction of signal intensity on MRI. An increase in the concentration of nanoparticles caused an increase in the MR contrast effect but a reduction in US intensity. The concentration of nanoparticles in a shell of PCNDs was optimized to obtain a dual-mode contrast effect. Biocompatibility, hemocompatibility, and immunogenicity assays showed that PCNDs were safe and non-immunogenic. Another finding was the dual-mode potential of unloaded PCNDs as T1 MR and US contrast agents. Results suggest the excellent potential of these PCNDs for use as dual-mode contrast agents for both MRI and US.
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31
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Wang J, Lin Z, He X, Song M, Westerhoff P, Doudrick K, Hanigan D. Critical Review of Thermal Decomposition of Per- and Polyfluoroalkyl Substances: Mechanisms and Implications for Thermal Treatment Processes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:5355-5370. [PMID: 35446563 DOI: 10.1021/acs.est.2c02251] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Per- and polyfluoroalkyl substances (PFASs) are fluorinated organic chemicals that are concerning due to their environmental persistence and adverse human and ecological effects. Remediation of environmental PFAS contamination and their presence in consumer products have led to the production of solid and liquid waste streams containing high concentrations of PFASs, which require efficient and cost-effective treatment solutions. PFASs are challenging to defluorinate by conventional and advanced destructive treatment processes, and physical separation processes produce waste streams (e.g., membrane concentrate, spent activated carbon) requiring further post-treatment. Incineration and other thermal treatment processes are widely available, but their use in managing PFAS-containing wastes remains poorly understood. Under specific operating conditions, thermal treatment is expected to mineralize PFASs, but the degradation mechanisms and pathways are unknown. In this review, we critically evaluate the thermal decomposition mechanisms, pathways, and byproducts of PFASs that are crucial to the design and operation of thermal treatment processes. We highlight the analytical capabilities and challenges and identify research gaps which limit the current understanding of safely applying thermal treatment to destroy PFASs as a viable end-of-life treatment process.
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Affiliation(s)
- Junli Wang
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Nevada 89557-0258, United States
| | - Zunhui Lin
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287-3005, United States
| | - Xuexiang He
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Nevada 89557-0258, United States
| | - Mingrui Song
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Nevada 89557-0258, United States
| | - Paul Westerhoff
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287-3005, United States
| | - Kyle Doudrick
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - David Hanigan
- Department of Civil and Environmental Engineering, University of Nevada, Reno, Nevada 89557-0258, United States
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32
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Weber NH, Delva CS, Stockenhuber SP, Grimison CC, Lucas JA, Mackie JC, Stockenhuber M, Kennedy EM. Modeling and Experimental Study on the Thermal Decomposition of Perfluorooctanesulfonic Acid (PFOS) in an α-Alumina Reactor. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.2c00339] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nathan H. Weber
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Cameron S. Delva
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Sebastian P. Stockenhuber
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | | | - John A. Lucas
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - John C. Mackie
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Michael Stockenhuber
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Eric M. Kennedy
- Discipline of Chemical Engineering, School of Engineering, University of Newcastle, Callaghan, New South Wales 2308, Australia
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33
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Falandysz J, Jiménez B, Taniyasu S. Per- and polyfluorinated substances: An environmental update. CHEMOSPHERE 2022; 291:132876. [PMID: 34774902 DOI: 10.1016/j.chemosphere.2021.132876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Affiliation(s)
- Jerzy Falandysz
- Department of Toxicology, Faculty of Pharmacy, Medical University of Lodz, 1 Muszyńskiego Street, 90-151, Łódź, Poland.
| | - Begoña Jiménez
- Department of Instrumental Analysis and Environmental Chemistry, Institute of Organic Chemistry (IQOG-CSIC), Juan de la Cierva 3, 28006, Madrid, Spain.
| | - Sachi Taniyasu
- Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1, Onogawa, Tsukuba, Ibaraki, 305-8569, Japan.
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34
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Altarawneh IS, Altarawneh M. On the formation chemistry of brominated polycyclic aromatic hydrocarbons (BrPAHs). CHEMOSPHERE 2022; 290:133367. [PMID: 34933028 DOI: 10.1016/j.chemosphere.2021.133367] [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: 11/20/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
Brominated polycyclic aromatic hydrocarbons (BrPAHs) have been consistently detected in various environmental matrices, and measured at alarming rates in stack emissions. However, formation mechanisms and bromination patterns of BrPAHs remain unclear. This contribution constructs detailed mechanistic pathways for the synthesis of selected BrPAHs (namely bromine-bearing naphthalene, acenaphthylene, anthracene, and phenanthrene). Mapped-out pathways follow the Bittner-Howard's route in the hydrogen abstraction acetylene addition (HACA) mechanism, in which a second C2HBr molecule is added to the first one. Constructed kinetic model portrays temperature-dependent profiles of major and minor species. Direct loss of an H atom from the acetylenic fragment appears to be more important at elevated temperatures, when compared with further addition of C2HBr cuts or ring-cyclization reactions. The occurrence of closed-shell Diels-Alder pathway should be inhibited owing to sizable enthalpic barriers. Fukui Indices for electrophilic substitutions (f-1) establish bromination' s pattern of selected BrPAHs. The diradical character of BrPAHs coupled with electron-deficient C(Br) sites, render BrPAHs as potent precursors for the formation of environmentally persistent free radicals (EPFRs). Findings reported herein shall be useful in comprehending the formation chemistry of BrPAHs, a less-investigated category of toxicants in thermal systems.
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Affiliation(s)
- Ibrahem S Altarawneh
- Pharmaceutical and Chemical Engineering Department, German Jordanian University, Amman, 11180, Jordan
| | - Mohammednoor Altarawneh
- United Arab Emirates University, Department of Chemical and Petroleum Engineering, Al-Ain, 15551, United Arab Emirates.
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35
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Adi MA, Altarawneh M. Thermal decomposition of heptafluoropropylene-oxide-dimer acid (GenX). CHEMOSPHERE 2022; 289:133118. [PMID: 34863723 DOI: 10.1016/j.chemosphere.2021.133118] [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: 10/18/2021] [Revised: 11/25/2021] [Accepted: 11/27/2021] [Indexed: 06/13/2023]
Abstract
Incineration appears as a viable strategy in the disposal of the notorious perfluoroalkyl substances (PFASs) in a process that typically leads to fluorine mineralization. Central in the design of such operation is to comprehend the underlying chemical mechanisms that dictate thermal fragmentation of PFASs into smaller perfluorinated cuts and HF. Among notable short-chain PFASs entities is the heptafluoropropylene-oxide-dimer acid (HFPO-DA, C5F11C(O)OH), commercially known as GenX synthesized as a possible replacement of other PFASs compounds. However, reaction pathways that underpin the degradation of GenX at temperatures relevant to its decomposition in incinerators (i.e., cement kilns), remain unknown. Herein, we map out all plausible initial reactions that govern the thermal decomposition of GenX. Simultaneous elimination of HF and CO2 appears as the kinetically most favored channel with an accessible activation enthalpy of ∼62.0 kcal/mol. Fission of the ether linkage in the 1,1,1,2,2,3,3-heptafluoro-3-[(1-fluoroethenyl)oxy] propane molecule (that forms after HF/CO2 elimination) affords a wide array of CnFm cuts, most notably CF2 at elevated temperatures. Constructed kinetic model plots temperature-dependent profiles of important species. It is predicted that GenX to commence decomposition around 700 K at a residence time of 2.0 s, a value that is generally applied in incinerators. Findings from the study call to further investigate interactions between the predicted major fluorine carriers (HF and CF2) and other constituents encountered in relevant incineration mediums, most notably, calcium hydroxides and polymeric materials.
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Affiliation(s)
- Maissa A Adi
- Department of Chemical and Petroleum Engineering, United Arab Emirates University, PO Box 15551, Al-Ain, United Arab Emirates
| | - Mohammednoor Altarawneh
- Department of Chemical and Petroleum Engineering, United Arab Emirates University, PO Box 15551, Al-Ain, United Arab Emirates.
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