Download or read book Sorption mediated Chemical Processes for the Versatile Treatment of Per and Polyfluoroalkyl Substances PFAS in Complex Media written by Naomi Gevaerd de Souza and published by . This book was released on 2022 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, per- and polyfluoroalkyl substances (PFAS) have gained notoriety due to environmental and health concerns. These molecules are chemically stable which contributes to their persistence in biological systems and their increased detections in surface waters. Treatment of highly persistent PFAS has been a challenging but significant task. The most practical technique for removal of PFAS is through adsorption onto granular activated carbon (GAC) or other novel materials. Meanwhile, PFAS are resistant to simple oxidation, and although decomposition of specific PFAS has been reported through advanced oxidation technologies, often energy-intense technologies capable of generating electrons such as ultraviolet radiation, microwave, or high temperatures are required when coupled with an oxidant to generate highly reactive radical species. The use of such technologies increases the cost and lowers its practical applicability. Hence, in an effort to develop a practical treatment technology, an adsorption-based decomposition technology was envisioned. The high surface area of GAC poses a unique opportunity of housing reactive materials inside the pores. To achieve this, zero valent iron (ZVI), previously demonstrated to reductively delahogenate other persistent pollutants, was incorporated into the pores of the GAC, so called reactive activated carbon (RAC). Additionally, to generate highly oxidizing radical species per sulfate (PS) was injected. Hence, once PFAS are encapsulated inside the pores, a combination of both reductive and oxidative species is present in close proximity to decompose the much recalcitrant PFAS. To demonstrate its effectiveness and understand its behavior, 6 PFAS of different functional groups and carbon chain lengths were investigated. An adsorption isotherm was first developed to test the affinity of the selected GAC. Then, the effects of reaction temperature, injection of PS, and presence of soil on removal of PFAS in water by RAC were evaluated. Results showed that RAC conjugated with PS at 60 °C exhibited decomposition of PFAS, exclusively all 3 carboxylic PFAS tested, obviously producing various identifiable short chain PFAS. Carboxylic PFAS were removed via physical adsorption combined with chemical decomposition while sulfonic PFAS were removed via solely adsorption mechanism. The presence of soil particles did not greatly affect the overall removal of PFAS. Carbon mass balance suggested that chemical oxidation by radical mechanisms mutually influences, in a complex manner, PFAS adsorption to GAC, ZVI and its iron derivatives, and soil particles. Nonetheless, all tested 6 PFAS were removed significantly. If successfully developed, the adsorption-mediated decomposition strategy may work for treatment of complex media containing PFAS and co-contaminants under different environmental settings. Future studies are required, to ensure the decomposition of PFAS exclusively inside the pores of RAC, additionally the synthesis of RAC containing different types of reactive metals and oxidants should be investigated. Pilot scale studies should also be conducted to simulate treatment beds and evaluate the effectiveness of the system.

Download or read book Adsorption Processes for Water Treatment written by Samuel D. Faust and published by Elsevier. This book was released on 2013-10-22 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adsorption Processes for Water Treatment discusses the application of adsorption in water purification. The book is comprised of 10 chapters that detail the carbon and resin adsorptive processes for potable water treatment. The text first covers the elements of surface chemistry and then proceeds to discussing adsorption models. Chapter 3 tackles the kinetics of adsorption, while Chapter 4 deals with batch systems and fixed fluid beds. Next, the book talks about the physical and chemical properties of carbon. The next two chapters discuss the adsorption of organic compounds and the removal of inorganic compounds, respectively. The eighth chapter presents operational, pilot plant, and case studies. Chapter 9 discusses the biological activated carbon treatment of drinking water, and Chapter 10 covers the adsorption of macroreticular resins. The book will be of great use to both researchers and professionals involved in the research and development of water treatment process.

Download or read book Advanced Sorption Process Applications written by Serpil Edebali and published by BoD – Books on Demand. This book was released on 2019-02-20 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: At the beginning of the twenty-firstst century, separation processes presented a comprehensive application of the major operations performed by various industries, such as chemical, food, environmental, and biotechnology. Sorption, one of the preferred separation processes because of its effectiveness at different interfaces, has caught the attention of many scientists. This book is aimed at gaining a general knowledge of sorption and a number of extremely important applications, as well as recognizing its functions and paramount importance in chemical and biochemical plants, including environmental treatment. Moreover, progress in the phenomenon is highlighted in this book. To help provide instruction in the important sorption processes, we have chosen authors who have extensive industrial and academic experience in closing the gap between theory and practice. Crucial progress in the theoretical information section of sorption has been achieved, mainly through the development of new techniques that examine the usage of various sorbents, including nanomaterials for the removal of various pollutants. We have subdivided the book into several sections, one of which is focused on applications of the sorption process, which presents real results of the recent studies and gives a source of up-to-date literature. The relationship between the sorption process and isotherm and kinetics modeling is analyzed in another chapter. This book will be a reference book for those who are interested in sorption techniques from various industries.

Download or read book Bioaccumulation Fate and Treatment of Per and Polyfluoroalkyl Substances PFAS written by Asa James Lewis and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Per- and polyfluoroalkyl substances (PFAS) are a large and diverse class of man-made chemicals that are persistent and difficult to degrade in the environment. PFAS are characterized by the presence of carbon-fluorine bonds, the strongest bond in organic chemistry, which leads to great thermal and chemical stability. Often these properties provide industrial and consumer products with chemical and temperature resistance, surfactant behavior, and stain or water resistance. Currently, the problem of PFAS in the environment starts with their synthetic generation, use in products, and subsequent release to the environment where they can bioaccumulate and persist. PFAS have globally impacted aquatic ecosystems through major pathways such as direct release into the environment (e.g., fire-fighting trainings with aqueous film forming foams (AFFF)), inadequately treated industrial effluents, land-applied biosolids, and atmospheric deposition. Once released to the environment, specifically in water, many PFAS compounds tend to accumulate in ecosystems through bioaccumulation. In water, some PFAS are mobile, pose risks to all levels of an ecosystem, and are particularly difficult to remove or degrade. To address the release and accumulation in the environment, major strides must be made in terms of regulations, development of analytical techniques, mechanistic pathways understanding related to fate and transport, and advancement of treatment technologies to address the pollution whether it is large scale or site-specific remediation efforts. The goal of this dissertation is to provide further insight into bioaccumulation of PFAS in aquatic matrices, fate and transport in land-applied biosolids, and to develop a plasma treatment technology to destroy PFAS. Regarding bioaccumulation in aquatic matrices, geochemical factors have been demonstrated to impact PFAS partitioning in aquatic ecosystems and to impact bioaccumulation, but little is known related to the mechanistic understanding of the effects of elevated divalent cation concentrations of magnesium (Mg2+) and calcium (Ca2+) on macroinvertebrates. Therefore, as part of this dissertation, the impacts of Mg2+ and Ca2+ on PFAS bioaccumulation in three different macroinvertebrates species, Lumbriculus variegatus (L. variegatus), Elliptio complanata (E. complanata), and Physella acuta (P. acuta) were investigated, where it was demonstrated that the increased divalent cations concentrations impact the bioavailability of PFAS and the mechanisms responsible were discussed. L. variegatus had significantly higher PFAS bioaccumulation than P. acuta and E. complanata, likely due to higher levels of activity and interactions/ingestion of the contaminated sediment. "High Mg2+" (7.5 mM Mg2+) and "High Ca2+" (7.5 mM Ca2+) conditions generally had observable higher bioaccumulation factors (BAFs) than the "Reference Condition" (0.2 mM Ca2+ and 0.2 mM Mg2+) for PFAS with perfluorinated chain lengths greater than six carbons. Long-chain PFAS dominated the PFAS profiles of the macroinvertebrates for all classes of compounds studied, PFCA, PFSA, and FTS. These results indicate that the specific organism studied is most impactful regarding bioaccumulation, but divalent cation concentration has observable impacts between species depending on the environmental conditions. With respect to the release of PFAS from land-applied biosolids, the influence of microbial weathering on the partitioning of PFAS over a period of three months was investigated to see the impacts on fate and transport in biosolids. We found that the PFAS biosolids-water partitioning coefficients (Kd) were demonstrated to decrease, on average, 0.4 log over the course of the study. Additionally, the solid characteristics were characterized (lipids, proteins, and organic matter) and were observed to have sharp decreases over the first ten days, aligning with the most rapid changes in Kd. As a result, a multiple linear regression model was built to predict PFAS partitioning behavior in biosolids based on the biosolids characteristics and PFAS characteristics. Among the evaluated independent variables, statistical analyses demonstrated that the most significant solids characteristics that impacted PFAS partitioning were organic matter, proteins, lipids, and molecular weight of organics. A multiple linear regression model was built to predict PFAS partitioning behavior in biosolids based on solid characteristics of the biosolids and PFAS characteristics with a R2 value of 0.7391 when plotting predicted and measured log Kd. The findings from this work reveal that microbial weathering can play a significant role in the eventual fate and transport of PFAS and their precursors from biosolids. Since PFAS have been demonstrated herein to accumulate in aquatic matrices and rapidly partition from biosolids during biotic weathering processes, there is a need to effectively remove PFAS from water to decrease the environmental accumulation and transport. We report as part of this dissertation the development of a non-thermal plasma treatment system to degrade PFAS in liquid solutions. It was observed that this technology was able to rapidly degrade PFAS compounds but the degree of degradation and defluorination was highly depending on perfluorinated alkyl chain lengths, with those compounds with greater than 8 perfluorinated carbons achieving greater than 90% removal in one hour of treatment. The combination of the energy efficiency of this treatment being on the order of magnitude of other emerging destructive technologies and its effectiveness shows promise for the application of non-thermal plasmas for PFAS removal in water. The lowest EEo for PFOS was 23.2 kWh/m3/order and 213.4 kWh/m3/order for PFOA, similar with existing technologies (which range from 10 to 10,000 kWh/m3/order). These results indicate that non-thermal air plasma discharges are promising technologies for treatment of PFAS that should be further researched and developed.

Download or read book Assessment of Water Treatment Technologies for Per and Polyfluoroalkyl Substances PFAS in Multiple Matrices written by Vanessa Maldonado and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ubiquitous presence of per-and polyfluoroalkyl substances (PFAS) in the environment resulted in extensive water contamination that poses a significant risk to human health and biota. Continuous research efforts aim to develop efficient treatment technologies to treat PFAS in water, break the PFAS accumulation cycle in the environment, and improve the efficiency of emerging technologies. In this thesis work, selected treatment technologies including electrochemical oxidation and dielectrophoresis-enhanced adsorption were used to assess and advance the state-of-the-art for PFAS remediation in multiple matrices, not previously addressed.A boron-doped diamond (BDD) flow-through cell was used to evaluate the electrochemical oxidation of perfluoroalkyl acids (PFAAs) in landfill leachates. Multiple leachates with a concentration of individual PFAAs in the range of 102 -104 ng/L were treated. The effect of current density and variability of the composition of leachates was investigated. Non-detect levels and >90% removal of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were reached for all leachates tested after electrochemical treatment. Although high removal efficiencies for long-chain PFAAs were obtained, high concentrations of short-chain PFAAs were generated and associated with the transformation of perfluoroalkyl acid (PFAA) precursor compounds.In the second part of this thesis research, the oxidative transformation of PFAA-precursors typically present in leachates was addressed for the first time. Target and suspect PFAS were identified in a landfill leachate and their concentrations during electrochemical treatment were quantified over time. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF) measurements of the leachate identified 53 PFAS compounds and 19 PFAS classes. Multiple PFAS were reported for the first time in landfill leachates. The evaluation of the intermediate and final products generated during the electrochemical treatment showed evidence of known electrochemical degradation pathways.Coupling destructive technologies (e.g., electrochemical oxidation) with concentration technologies (e.g., ion exchange (IX), adsorption) in a treatment train approach could reduce the treatment cost of destructive technologies and increase their feasibility. Therefore, in the next part of this work, electrochemical oxidation of PFAAs from the concentrated waste of IX still bottoms was assessed at laboratory and semi-pilot scales. The concentrated waste resulted from the treatment of PFAAs-impacted groundwater with IX resins. Multiple current densities were evaluated at laboratory scale and the optimum current density was used at the semi-pilot scale. The results at the laboratory and semi-pilot scales allowed for >99% and >94% removal of total PFAAs with 50 mA/cm2, respectively. Defluorination values, energy consumption, and implications were discussed.The third matrix addressed for PFAS remediation was drinking water. Dielectrophoresis-enhanced adsorption was used for the removal of low concentrations of PFOA. This study introduced a coaxial-electrode cell (CEC) that allowed for the generation of a non-uniform electric field to enhance the adsorption of PFOA. Experiments were performed in batch and continuous-flow modes. The dielectrophoretic-enhanced adsorption in batch mode resulted in a 4, 7, and 8-fold increase in the removal of PFOA with 5, 25, and 50 V when compared to adsorption only. The performance of the CEC in continuous-flow mode allowed for an increase of up to 2.4-fold in the PFOA removal with 25 V. The results highlighted the benefits of using a dielectrophoresis-enhanced adsorption process for the removal of PFOA from water. Overall, results from this thesis contribute to the understanding of the electrochemical degradation of PFAS in multiple matrices and introduce an alternative process to enhance the widely used adsorption technology for PFAS removal. Treatment implications of each matrix are discussed and provide a clear baseline for future research, development, and scale-up of treatment technologies for PFAS remediation.

Download or read book Sorption Processes and Pollution written by Grégorio Crini and published by Presses Univ. Franche-Comté. This book was released on 2010 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Roles of Chemical Additives in the Removal of Per and Polyfluoroalkyl Substances PFAs from Water in Plasma Treatment Process written by Jacob M. .Deangelis and published by . This book was released on 2021 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sorption Enhancement of Chemical Processes written by and published by Academic Press. This book was released on 2017-11-29 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sorption Enhancement of Chemical Processes, Volume 51 compiles the latest, state-of-the-art progress in the area of sorption enhanced processes. Topics in this updated volume include Sorption-enhanced water-gas-shift and steam methane reforming, CO2 sorbents for sorption enhanced steam reforming, Reactor design for Sorption Enhanced Reforming using Ca-Cu chemical loops, Sorption-enhanced reaction with Simulated Moving Bed reactor (SMBR) and PermSMBR technologies, and the Process design and Technoeconomic assessment of sorption enhanced systems. This series contains contributions from leading scientists on the topics presented, providing tactics on a multiscaling approach, from materials, to reactor, to process design. - Contains reviews by leading authorities in their respective areas - Presents up-to-date reviews of sorption enhancement of chemical processes - Includes a broad mix of U.S. and European authors, as well as academic, industrial and research institute perspectives

Download or read book Sorption of Perfluoroalkyl and Polyfluoroalkyl Substances PFASs by Natural and Anthropogenic Carbonaceous Sorbents written by Yue Zhi and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "As a large number of perfluoroalkyl and polyfluoroalkyl substances (PFASs) has been extensively used in industrial and consumer products, many of these species are detected in the global environment and biota, including some carcinogenic ones. Perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) are examples of PFASs currently subject to strict regulatory and scientific scrutiny. There are many other analogous compounds, such as those used in aqueous film-forming foams (AFFFs), for which environmental fate and effect are little known. In addition, high chemical stability and hydrophilicity of PFASs pose challenges to effective treatment and mitigation of those present in groundwater and drinking water sources. The objective of this research was to elucidate interactions between PFASs and naturally occurring and engineered carbonaceous materials, the knowledge base needed for PFAS risk assessment and treatment. The research first examined the interactions between commercial adsorbents with two most prominent PFAS species (PFOA and PFOS), to identify the ways in which water treatment efficiency for the PFASs can be improved. The study assessed the sorption of PFOS and PFOA onto as-received and surface-modified carbonaceous adsorbents using single-solute batch sorption experiments, and the main carbon characteristics controlling the uptake of PFASs were identified. Adsorbent surface chemistry played a more important role in controlling the extent of uptake than physical properties. High carbon surface basicity was closely linked to high PFOS and PFOA affinity. Prior to any modification of the carbon materials, synthetic polymer-based Ambersorb and activated carbon fibers were the most effective adsorbents due to their basic character. Surface modification, more so with ammonia gas treatment than with high-temperature thermal treatment, greatly improved sorption of PFOS and PFOA by wood-based carbons and activated carbon fibers. The research then focused on the role that soil organic matter (SOM) and pyrogenic carbonaceous materials (PCMs) played in determining the transport potential of a range of perfluoroalkyl acids (PFAAs) and their chemical precursors (PrePFAAs). A novel dynamic HPLC-based column method was developed to determine distribution coefficients (Koc) between SOM and water at various conditions. PrePFAAs with betaine, sulfonamide betaine, and quaternary amine functional groups exhibited higher Koc values than the PFAAs with the same perfluoroalkyl chain length. Calcium ion had a positive impact on the sorption of anionic PFAAs to SOM while showing a negative impact on the PrePFAAs. Moreover, an increase in pH reduced sorption of all the PFASs to SOM. In comparison, sorption of PFASs to PCMs (charcoal and soot) was stronger and less linear than SOM, indicating that PCMs could be a more significant sink to PFASs in the firefighting training sites where regular releases of AFFFs resulted in PFAS pollution of soil and groundwater. The role of PCMs was more pronounced than SOM at lower aqueous concentrations without an attenuation effect. Additionally, apparent sorption-desorption hysteresis exhibited by PCMs was sorbate-specific, and the soot had the highest hysteresis among all the sorbents. These findings illustrate the importance of considering the surface chemistry of adsorbents, along with solution chemistry when investigating PFAS uptake by carbonaceous materials of different origins. Furthermore, the results obtained emphasize the need to evaluate the interactions between PrePFAAs and PCMs, in the efforts to delineate the behaviours of PFASs in soil and groundwater impacted by AFFFs, as well as to decide remediation strategies. " --

Download or read book Per and Polyfluoroalkyl Substances PFAS Degradation by Nanoscale Zero valent Iron Under Light for Water Reuse written by Chunjie Xia and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wastewater reclamation and reuse have been increasingly practiced as sustainable strategies to meet water demands, particularly in regions threatened by water shortages. However, one of the biggest challenges for reusing wastewater effluents (WEs) as irrigation water is to remove emerging organic contaminants such as persistent and potentially bioaccumulated per- and polyfluoroalkyl substances (PFAS), whose presence may result in adverse impacts on crops, soils, aqueous ecosystems, and human health. Photocatalysis is an effective and promising technique to remediate PFAS in aqueous media. This dissertation aims to: i) Develop a novel, environmental-friendly, and low-cost treatment process for PFAS removal and degradation for water reuse; ii) Optimize the experimental conditions and investigate the removal mechanisms of PFAS with different structures in this novel process; iii) Scale up this treatment process and apply it to treatment of WEs in a point-of-use (POU) system. First, ultraviolet (UV) C /nanoscale zero-valent iron (nZVI, Fe0 nanoparticles (NPs)) system is used for the first time to induce PFAS photocatalytic removal from aqueous solution. Oxidative and/or reductive degradation of three representative PFAS - perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorooctane sulfonate (PFOS) was achieved using Fe0 NPs under UVC light both with and without presence of oxygen. However, no PFAS removal was observed either under visible light and in the dark, and much lower PFAS degradation was achieved under UVA light. Higher degradation and defluorination efficiencies were obtained for longer chain PFNA compared to PFOA, and higher degradation and defluorination of PFAS were achieved without presence of O2 compared to with O2. The degradation of PFOA and PFOS followed first order reaction kinetics with the highest efficiencies achieved of 97.6, >99.9, and 98.5% without presence of O2 for PFOA, PFNA, and PFOS, respectively. The degradation efficiencies increased with the increase of nZVI concentrations in the range of 1-100 mg/L. The degradation efficiency of PFOA using bare Fe0 NPs was higher than that using 1% PVP-coated Fe0 NPs in the initial 6 h. Second, the removal mechanism of PFAS in UVC/Fe0 NPs system was obtained by testing the concentrations of iron ions (Fe2+/Fe3+), intermediate products, and reactive oxygen species (ROS, e.g., ·O2- and ·OH) generated, and conducting ROS quenching experiments. The proposed degradation pathway of PFCAs (PFNA and PFOA) was initiated from PFOA/PFNA oxidation by transferring an electron of the carboxylate terminal group of PFOA/PFNA to the Fe(III)-carboxylate complex, then followed by decarboxylation−hydroxylation−elimination−hydrolysis (DHEH) pathway and the accompanying CO2 and F− release. The generated shorter chain PFCAs also underwent degradation with time in the system. This proposed degradation pathway was confirmed by the formation of shorter chain PFCAs, e.g. PFHpA, PFHxA, PFPeA, and PFBA, F- ions, and rapid consumption of Fe3+. For PFOS, besides H/F exchange pathway and chain-shortening (DHEH pathway) to form short chain PFAS during PFCA degradation, desulfonation to form PFOA followed by PFOA degradation also happened. These pathways were suggested by the formation of intermediates -- trace amount of shorter chain PFCAs, 6:2 FTS, PFHpS, and F- ions. ·O2- and ·OH were not involved in PFOA degradation in the UVC/Fe0 NPs system with presence of O2, while they may be involved in PFOS degradation, e.g., desulfonation to form PFOA, which were suggested by the results of quenching experiments. And introducing H2O2 into the UVC/Fe0 NPs system resulted in lower PFOA degradation efficiency and defluorination efficiency, which also indicated that ·OH may not be involved in PFOA degradation. Hydrated electrons e-aq that can be involved in desulfonation, defluorination, and C-C bond scission processes were likely quenched by the presence of oxygen to reduce the degradation and defluorination efficiencies; plus, presence of Fe0 NPs may promote the generation of hydrated electrons. Last, UVC/Fe0 NPs system was used to degrade PFAS from WEs in both bench scale and in a scale up POU system. The degradation efficiencies of PFAS in WEs from both wastewater treatment plants (WWTP) were lower than that in deionized water, likely reflecting the complex compositions in the environmental media. Optimal degradation efficiencies of 90±1%, 88±1%, and 46±2% were obtained for PFNA, PFOS, and PFOA, respectively, each starting from 0.5 μg/L using bare Fe0 at pH 3.0 after 2 h. PFAS removal and bacterial inactivation were achieved simultaneously in the POU system using Fe0 NPs without and with rGO support under UVC irradiation in WEs, although the PFAS levels were still above the regulation levels for discard. These pilot tests provided more data and experiences for the real applications of UVC/Fe0 NP system to PFAS contaminated wastewater or other water matrix treatment.Overall, this research demonstrated a cost-effective and environment-friendly method -- UVC/Fe0 NPs method for PFAS (i.e., PFOA, PFNA, and PFOS) degradation from WEs for water reuse both with and without presence of oxygen. The possible degradation mechanisms of PFAS with different structures were obtained by testing the concentrations of iron ions, intermediate products, and reactive oxygen species (ROS) involved in the reactions. The developed technology can be potentially applied to treat other environmental media (e.g., groundwater, landfill leachate) that are contaminated by PFAS from previous anthropogenic activities.

Download or read book Per and Polyfluoroalkyl Substances PFASs and Aqueous Film Forming Foam Impacted Sites written by Krista A. Barzen-Hanson and published by . This book was released on 2017 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Public attention and concern about per- and polyfluoroalkyl substances (PFASs) are increasing due to detection of PFASs in drinking water supplies, the environment, including remote locations, and wildlife and to the lowering of the federal health advisory levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in drinking water. Aqueous film-forming foams (AFFFs), which typically contain anionic, zwitterionic, and cationic PFASs, are one route of environmental entry for PFASs. AFFFs were routinely applied since the 1960s to extinguish hydrocarbon-based fuel fires during emergencies and fire fighter training. Routine releases of AFFF into the environment have resulted in high concentrations (mg/L) of PFASs in groundwater. Attention typically focuses on the well-known homologs of the perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs), including PFOA and PFOS, and other anionic, zwitterionic, and cationic PFASs receive little attention. Recent data on AFFF-impacted groundwater indicates that ~ 25% of the PFASs are currently unidentified. A complete understanding of the composition of PFASs in AFFF-impacted groundwater is needed in order to investigate biodegradation pathways and to develop effective remediation techniques that capture PFASs with a wide range of water solubilities and subsurface mobilities. Zwitterionic and cationic PFASs present in groundwater, soil, and sediment have not been characterized with respect to partitioning (sorption) behavior. Sorption studies typically focus on a select number of well-known PFCAs and/or PFSAs, and a limited number of studies simulate AFFF discharge field conditions. By enhancing understanding of zwitterionic and cationic PFAS sorption, transport and likely subsurface location (i.e. predominantly in groundwater or sorbed to soil) can better direct subsurface remediation efforts and mitigate off-site migration. Chapter 2 discusses a data analysis test for non-target analysis and the subsequent serendipitous discovery of two ultrashort chained PFSAs. Select 3M AFFFs and AFFF-impacted groundwater samples, each from 11 different U.S. military bases were analyzed using quadrupole time-of-flight mass spectrometry (qTOF-MS). Kendrick mass defect plots were used to identify known homologs within a homologous series. Careful inspection of the PFSA homologous series led to the serendipitous discovery of the C2 and C3 PFSAs in 3M AFFF and AFFF-impacted groundwater. The C2 and C3 PFSAs were quantified using liquid chromatograph tandem mass spectrometry. Chapter 3 uses the developed non-target data analysis strategy to attempt to close the mass balance of PFASs in AFFF-impacted groundwater. Select 3M and fluorotelomer AFFFs, commercial products, and AFFF-impacted groundwater samples from 15 different sites were used to identify the remaining PFASs. Liquid chromatography qTOF-MS was used for compound discovery. Nontarget analysis and suspect screening were conducted. For nontarget analysis, a ‘nontarget’ R script in combination with Kendrick mass defect plots aided in compound identification. Suspect screening compared detected masses against a list of previously reported PFASs. Forty novel classes of anionic, zwitterionic, and cationic PFASs were discovered, and an additional 17 classes of previously reported PFASs were observed for the first time in AFFF and/or AFFF-impacted groundwater. All 57 classes received an acronym and IUPAC-like name. Overall, of the newly discovered PFASs, ~ 68% were zwitterionic or cationic PFASs. Chapter 4 selects the representative National Foam AFFF to determine the soil properties influencing the sorption of model anionic fluorotelomer sulfonates (FtSs), zwitterionic fluorotelomer sulfonamido betaines (FtSaBs), and the cationic 6:2 fluorotelomer sulfonamido amine (FtSaAm). Batch sorption experiments were conducted using the whole National Foam AFFF, with initial aqueous phase concentrations of the 6:2 FtSaB ranging from 1,000 to 138,000,000 ng/L, which represent concentrations of dilute groundwater plumes up to the application of 3% AFFF used in fire fighter training and emergency responses. Six blank soils with varying organic carbon, cation exchange capacity (CEC) and anion exchange capacity as well as a select soil buffered to pH 4 and 7 were used to determine the factors predominantly impacting sorption. A new, aggressive soil extraction method was developed due to incomplete mass balance of the FtSaBs and the 6:2 FtSaAm using published extraction methods. Hydrophobic interactions drove the sorption of the anionic FtSs, while the FtSaBs were influenced primarily by CEC. The 6:2 FtSaAm was depleted from the aqueous phase in all but one soil, and therefore, sorption is likely driven by a combination of CEC and organic carbon.

Download or read book Exploring the Factors that Determine the Adsorption of Per and Polyfluoroalkyl Substances on Conventional Adsorbents and Novel Cyclodextrin Polymers with Different Surface Properties written by Ri Wang and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the concerns over the ubiquity and toxicity of per- and polyfluoroalkyl substances (PFASs) grow, research has focused on finding both technically and financially efficient PFAS remediation technologies. When evaluating certain technologies, research has focused on the removal of perfluoroalkyl acids from water, but contaminated groundwater often contains complex mixtures of diverse groups of PFASs. Utilizing a more comprehensive method to evaluate the performance of different PFAS treatment technologies involving the consideration of environmental matrix complexity can bring more useful insights into practical application. Adsorption-based processes are among the most promising technologies available for PFAS removal from water. The conventional adsorbents including activated carbon (AC) and anion exchange (AE) resins have been implemented in pilot or full-scale processes targeting PFAS removal from water. Emerging adsorbents, including novel β-cyclodextrin polymers (CDPs), have also exhibited potential for PFAS removal from water. The efficacy of CDPs on PFAS removal and the importance of varying surface properties of different CDPs on determining the affinity and selectivity to contaminants have been demonstrated. However, the mechanisms by which adsorbates bind to CDPs remains poorly understood. More research is needed to elucidate the mechanisms about the relative contributions of hydrophobic and electrostatic interactions for the adsorption of PFASs on CDPs.Two studies were designed to systematically explore the potential of conventional adsorbents and novel CDPs to remove mixtures of PFASs from contaminated groundwater and probe the adsorption binding mechanisms for anionic PFAS removal on CDPs. The first study aimed to evaluate the performance of five adsorbents including one AC, one AE resin and three different CDPs with varying surface charges to remove 68 PFASs in contaminated groundwater integrating a suspect screening approach. The PFAS removal performance of the adsorbents was evaluated with respect to adsorption affinity, kinetics, and selectivity. This evaluation provided insights on the factors that determine PFASs adsorption, which can be associated with the increasing length of the perfluorinated tail or could be more strongly related to properties of the head group. The second study aimed to evaluate the relative contributions of hydrophobic and electrostatic interactions on the adsorption of anionic PFASs by CDPs under controlled experimental conditions in nanopure water and different salt-amended nanopure water matrices. This study provided new insights into the adsorption binding mechanisms between anionic PFASs and CDPs as a function of chain length, and revealed the effects of different types and concentrations of inorganic constituents on the adsorption mechanisms. Together, the research described in this thesis furthers the understanding of different PFAS removal patterns by different adsorbents, and the understanding of anionic PFAS adsorption mechanisms on CDPs. These findings can serve as guidance and knowledge support on the future development and practical application of CDPs for different PFAS species under a range of environmental conditions.

Download or read book Forever Chemicals written by David M Kempisty and published by . This book was released on 2021 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The book offers the educated reader both a broad overview of PFAS and a deeper understanding of specific PFAS issues. Without requiring an advanced degree, the reader will have knowledge of the big rocks that are associated with PFAS. Policy makers will appreciate the difficulties and pros and cons of new analytical methods and the difficulties of PFAS detection in various environmental media. Concerned citizens from the general public will be exposed to risk management thought strategies. The book will have value to teachers and students, it will demonstrate the push and pull between, environmental policy and water treatment operations and how that affects the cost PFAS-free drinking water"--

Download or read book Novel Adsorbents for Per and Polyfluoroalkyl Substances PFAS written by Yuhao Tian and published by . This book was released on 2019 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: The extensive presence of a group of emerging contaminants, per- and polyfluoroalkyl substances (PFAS), in surface water, groundwater, even drinking water, has attracted great attention due to their extraordinary persistence and potential toxicity. Because of their unique properties, PFAS are exceptionally challenging to be removed from the water. To face this challenge, efficient treatment technology is needed. Current treatment technologies have limitations such as slow adsorption, high cost, and low regeneration efficiency. Therefore, this study aims to explore mechanisms governing the adsorption of PFAS and utilize those mechanisms for the design of novel and low-cost adsorbents with regeneration ability for removal of PFAS from contaminated water. Three hypotheses were proposed: 1) Electrostatic interaction is more important than hydrophobic effects for PFAS adsorption; 2) Adsorption and desorption of PFAS can be controlled by changing surface charges; 3) Increasing hydrophobicity of adsorbents can improve the performance for long-chain PFAS adsorption, but not for short-chain PFAS. To test these hypotheses, three materials (transition metal dichalcogenides (TMDC), polypyrrole (PPy) and lignin), were selected to run the designed experiments. TMDC can adsorb pharmaceuticals and personal care products (PPCP) effectively through hydrophobic effects, but not PFAS, suggesting stronger electrostatic repulsion between negatively charged TMDC and anionic PFAS. The adsorption of PFAS by PPy mainly comes from electrostatic attraction and hydrophobic effects. By introducing positively charged functional groups (amine groups) onto lignin, the adsorption of PFAS was improved significantly. Spent lignin-based adsorbents can be regenerated to almost 100% in less than 1 hour by changing the pH to 10. Results from adsorption of PFAS by several modified lignin materials with different hydrophobicity showed that increasing hydrophobicity could improve adsorption for all tested PFAS, except for PFBA, probably due to its shorter tails, which may reduce the hydrophobic effects. This study provided a comprehensive understanding of the fundamental mechanisms governing adsorption of PFAS and developed novel adsorbents with fast adsorption kinetics, high capacities and the ability to be regenerated effectively. These adsorbents are supposed to be able to remove other ionic organic contaminants similar to PFAS in the environment effectively.

Download or read book Development of Reductive oxidative Treatment Strategy for the Removal of Per and Polyfluoroalkyl Substances PFAS in Water written by Akshay Chandrashekar Parenky and published by . This book was released on 2020 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: The detrimental health effects of halogenated compounds in humans has been well documented, and the frequent occurrence of per- and polyfluoroalkyl substances (PFAS)in the water environment is a recent global concern. Feasible and sensible treatment strategies are in dire need for environmental remediation and water treatment. Currently, efficient treatment is only obtained at a small scale and at a high energy cost. This research is presented in three subsections, where decomposition of selected PFAS was evaluated under advanced oxidation techniques. The first study involved decomposition of a polyfluoroalkyl substance, 6:2 fluorotelomer sulfonate (6:2 FTS), in which 2 carbons of the alkyl chain are hydrogenated making the molecule more vulnerable to degradation. The 6:2 FTS was tested against some of the common oxidants such aspersulfate (PS), peroxymonosulfate and hydrogen peroxide. Interestingly, 6:2 FTS was degraded by PS alone under ambient conditions. Several byproducts and fluoride release were observed and quantified. A decomposition pathway was proposed, and certain reaction intermediates were identified. Upon achieving successful degradation of 6:2 FTS, a highly oxidized perfluorinated compound, perfluoroctanesulfonic acid (PFOS) was investigated. The absence of C-H bonds makes the molecule more resilient to conventional oxidation, hence a synergistic approach of using reduction combined with advanced oxidation was envisioned. This strategy involved the use of electrons generated by zero valent iron as the reductive source in combination with highly reactive radical species such as sulfate radical and hydroxyl radicals as the oxidizing species. This combination of oxidation and reduction was evaluated under several conditions by changing factors such as concentration, pH, and temperature. Significant removal of PFOS was observed in most cases but no transformation was observed. However, when this system was tested for perfluorooctanoic acid (PFOA), decomposition byproducts were observed consisting of short chain compounds demonstrating the potential for this treatment strategy. Although decomposition of PFOA was achieved through the synergistic approach, the constraints of heat requirement reduce the practical applicability of the system. Since oxidants can be activated efficiently by transition metals, several different combinations of metal-oxidants were evaluated. Amongst these combinations, silver-PS was successful in decomposing a variety of carboxylic PFAS under ambient conditions without the use of any external energy source such as heat, ultra-violet or microwave. Significant byproduct and fluoride release were observed upon decomposition of selected PFAS. This system shows great potential for in situ application of PFAS remediation. The reaction mechanism for the system is complex and future studies should: i) investigate the role of silver and identify the reactive species responsible for the reaction, ii) identify an appropriate metal-oxidant pair capable of decomposing sulfonic PFAS, and iii) evaluate the efficacy of these systems for a wider range of PFAS.

Download or read book Symposium written by Symposium Resistant Sorption Processes. 1997, Las Vegas, Nev.. and published by . This book was released on 1999 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Two step Transformation of Per and Polyfluoroalkyl Substances PFAS written by Miranda Marini and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this project, I evaluated a two-step approach to breakdown of long-chain PFAS chemicals into innocuous byproducts. Ideally, UV-activated nanoparticles will cleave long-chain PFAS chemicals into shorter chains, and microbes will remove the fluorines from the smaller compounds. PFAS causes a variety of health problems, and current methods of PFAS transformation have high energy requirements. In contrast, a combination of UV-activated nanoparticles and microbes could transform PFAS with lower energy requirements and would take advantage of infrastructure already in place at wastewater treatment plants. I found that perfluorooctanoic acid (PFOA) can be transformed by 100-nm nanoparticles in a basic pH solution. In addition, microbes from wastewater treatment plants defluorinated smaller PFAS chemicals like MFA. In conclusion, this work provides promising results that a two-step transformation process of long-chain PFAS chemicals could be feasible.