<div> <p>In recent years, the presence of per- and polyfluoroalkyl substances (PFAS) in aquatic systems has led to research on their fate, effects and treatability. PFAS have been found in various environmental matrices including wastewater effluents, surface, ground, and drinking water. Perfluoroalkyl acids (PFAAs) are the class of PFAS most commonly tested due to their ability to migrate rapidly through groundwater and include perfluoroalkyl sulfonic acids (PFSAs) and perfluoroalkyl carboxylic acids (PFCAs). Of the globally distributed and persistent PFAAs, PFSAs are the most resistant to biological and oxidative chemical attack. This doctoral study focused on a reductive treatment approach with zero valent metals/bimetals nanoparticles (NPs) synthesized onto a carbon material to reduce NP aggregation. Initial work focused on exploring reactivity of different combinations of nano (n) Ni, nFe⁰ and activated carbon (AC) at 22 ^oC to 60 ^oC for transforming perfluorooctanesulfonate (PFOS) from which nNiFe⁰-AC at 60 ^oC led to transformation of both linear (L-) and branched (Br-) PFOS isomers. The remaining research focused on work with nNiFe⁰-AC at 60 ^oC in batch reactors including optimizing nNiFe⁰-AC preparation, quantifying PFOS transformation kinetics and evaluating the effects of PFAA chain length (C4, C6 and C8) and polar head group (PFSA versus PFCA) as well a groundwater matrix on transformation magnitude. Optimization of analytical methods to provide multiple lines of evidence of transformation including fluoride, sulfite and organic product generation was an ongoing throughout the research.</p> <p>nNiFe⁰-AC prepared with a 3-h synthesis stirring time led to the highest PFOS transformation of 51.1 ± 2.1% with generation of ~ 1 mole of sulfite (measured as sulfate) and 12 moles of fluoride. Several poly/per-fluorinated intermediates with single and double bonds were identified using quadrupole time-of-flight mass spectrometry (QToF-MS) in negative electrospray ionization (ESI-) mode with MS/MS fragmentation confirmation as well as one and later two desulfonated products with QToF negative atmospheric pressure chemical ionization (APCI-). All organic transformation products were found in only particle extracts as well as most of the sulfite generated. PFOS transformation kinetics showed that generated fluoride concentrations increased for the first day whereas sulfate concentrations continued to increase during the 5-d reaction. The transformation products identified showed defluorination of single- and double-bond structures, formation of C8 to C4 PFCAs and paraffins from cleavage of the C-S bond.</p> <p>The length of the perfluoroalkyl chain affected the length of time to achieve peak removal, but overall magnitude of transformation when reactions appeared complete were similar for both PFSAs and PFCAs. Like PFOS, PFOA transformation maxed in 1 d whereas shorter chains required more time to reach their peak removal, which is hypothesized to be due to lower sorption of the shorter chain PFAAs to the reactive surfaces. Measured F mass balance was higher for PFOS and PFOA (>90% F) compared to shorter chain PFAAs (~50-70% F). The Perfluorohexanesulfonate (PFHxS) and perfluorobutanesulfonate (PFBS) degradation products include single bond polyfluoroalkyl sulfonates and shorter-chain perfluoroalkyl carboxylates. For example, PFHxS transformation resulted in perfluorohexane carboxylic acid (PFHxA) and perfluorobutane carboxylic acid (PFBA). PFCA transformation products included per- & polyfluoroalkyl carboxylates with single bonds and alcohols with single and double bonds. The effect of inorganic matrix on transformation with nNiFe⁰-AC at 60 ^oC was explored using a contaminated groundwater collected at a former fire-training area in Massachusetts. Transformation appeared ‘generally’ lower than in the single-solute clean water systems, which may have been due to the presence of PFAS precursors that degraded to PFAAs and competitive adsorption between anionic PFAAs and inorganic ions onto the NP surface.</p><p>The research presented here demonstrates that nNiFe⁰-AC at 60 ^oC can mineralize PFAAs even in a typical groundwater matrix. Additional lab and pilot scale studies are needed to clarify the mechanisms leading to transformation as well as why transformation reactions plateau prior to all the parent compounds being transformed. The latter may be due to a poisoning phenomenon that can occur in closed systems, which may not occur in a flowing system more characteristic of an environmental scenario, as well as surface area and reactive site constraints or particle passivation.</p></div>

The persistent and toxic perfluoroalkyl acids (PFAAs) are ubiquitously present in the environment and reach humans predominantly via food and drinking water. The aim of the present study was to investigate the effect of low-grade (&lt;10 ng L-1 of single PFAAs) contaminated PFAAs drinking water on serum PFAA concentrations in a representative Swedish adolescent population, and to examine the influence of potential determinants on the variation of the PFAAs serum concentrations. This was done by using multivariate regression analysis on the possible determinants of blood serum PFAA concentrations in 479 Swedish adolescents, 10 to 21 years of age, who had left complete dietary and life style information in 2016-17 in the nation-wide food consumption survey Riksmaten Ungdom. Raw and drinking water samples (DW) from water treatment plants (WTPs) that delivered DW to participants schools were sampled in 2018, analysed for PFAAs, and used for assessing the participants DW PFAA exposure. Maternal education level and maternal birth country, consumption of fish, as well as age and sex were significantly associated with the participants PFAAs serum concentrations. DW concentrations as low as &lt;1 ng L for PFOA and PFHxS, &lt;0.45 ng L-1 for PFNA and &lt;4 ng L-1 for PFOS were significantly associated with increased adolescent serum concentrations of the PFAAs in question, which suggests that low-grade contaminated drinking water is an important exposure route for Swedish adolescents. For risk assessment purposes, it was investigated whether parts of the adolescent population exceeded the serum PFOS and PFOA concentrations corresponding to the current health-based reference intakes as assessed by the European Food Safety Authority (EFSA) and the U.S. Agency for Toxic Substances and Disease Registry (ATSDR). Around 1.7% and 2.7% of participants had PFOS serum concentrations exceeding serum levels used to derive the tolerable daily intake (TDI) (EFSA) and the minimum risk level (MRL) (ATSDR), respectively and a cause for concern was consequently identified. However, the high serum concentrations of participants exceeding the TDI and MRL serum concentrations belong to participants suspected to have been previously exposed to highly contaminated drinking water and not from consuming foods and beverages containing background concentrations of PFAAs.

In order to achieve a more stable and highly proton conducting membrane that is also cost effective, the perfluoroalkyl benzenesulfonylimides (PFSI) polymers are proposed as electrolyte for Proton Exchange Membrane Fuel Cells. 4-(trifluoromethyl)-2-diazonium perfluoro-3, 6-dioxa-4-methyl-7-octene benzenesulfonyl imide (I) is synthesized from Nafion monomer via a 5-step schematic reaction at optimal reaction conditions. This diazonium PFSI zwitterionic monomer can be further subjected to polymerization. The loss of the diazonium N2+ functional group in the monomer is believed to form the covalent bond between the PFSI polymer electrolyte and carbon electrodes support. All the intermediates and final products were characterized using 1H NMR, 19F NMR and IR spectrometry.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22058号 / 工博第4639号 / 新制||工||1723(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 米田 稔, 教授 清水 芳久, 教授 高野 裕久 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Atmospheric deposition has been suggested to be a major input pathway of perfluoroalkyl acids (PFAAs) to the Baltic Sea catchment area and to the Baltic Sea itself. However, the sources of PFAAs to the atmosphere are not well characterized. In this study we investigated if waste incineration plants in Sweden could be a source of PFAAs to the atmosphere and to the environment in general. Samples of the end products from waste incineration were collected at four different incineration plants. The plants differed in size and technical advancement and were considered to be representative for the majority of waste incineration plants in Sweden. The collected samples were slag from the furnaces, fly ash from the flue gases, “bambergkaka” (a mix of fly ash and sludge from wastewater treatment) as well as condensate and wastewater from the cleaning process of the flue gases. Two methods were developed, one for analysis of PFAAs in solid samples and one for water samples. Method validation showed good performance for both methods in terms of precision and accuracy, despite low recoveries obtained for the method for solid samples. The results from sample analysis revealed that PFAAs were present in all solid samples at concentrations in the low to sub ng/g range and in all but one condensate and wastewater samples at concentrations in the low to sub ng/L range. The quantified concentrations were used to estimate the potential annual discharges of PFAAs from waste incineration plants to the environment. Emission scenarios via landfills, via wastewater treatment plants and to the atmosphere were considered. The main conclusion of this study is that waste incineration in Sweden is not a significant source of PFAAs to the atmosphere or to the environment in general.

Perfluoroalkyl acids (PFASs) are toxic pollutants ubiquitously found in the ecosystem. Recent investigations have focused on describing their environmental behavior and spreading. This includes transportation by water, where groundwater can continue to spread the contaminants a long time after the use has ended. This thesis surveys the existing literature on the reactions in soil that decides the presence and composition of PFASs in groundwater. A chemical groundwater investigation was recently done by Stockholm’s Environmental and Health Administration. The thesis presents a quantitative analysis of the PFASs’ content in Stockholm’s groundwater to verify if it conforms to the literature. A statistical analysis of the ratio between perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) is included to test if the PFAS composition in groundwater is influenced by soil reactions. The literature states that due to the high water solubility, low volatility and moderate adsorption, PFASs are likely to be encountered in groundwater. The adsorption depends on both PFASs’ and soil’s properties. The quantitative analysis confirms the influence of the PFASs’ properties in Stockholm’s groundwater, where both more short-chained PFASs and carboxylates are present. However, the analysis could not confirm the influence of the soil properties in adsorption at normal environmental conditions. The statistical analysis shows that the ratio of PFOS to PFOA is increased in groundwater in comparison to stormwater (p &lt; 0.15). The increase cannot be explained by the hypothesis that the adsorption of PFAS governs this behavior, since PFOS is a sulfonate and longer than PFOA. An explanation is found in the degradation of precursors, which seems to contribute to PFOS concentrations in groundwater. This shows the important contribution of degradation of precursors to PFOS concentrations and motivates further investigations on the matter.

It is very promising to introduce diazonium moiety into Nafion monomer based Diazonium (Perfluoroalkyl) Arylsufonylimide (PFSI) monomers for further polymerization and chemical grafting onto carbon electrodes as innovative electrolyte materials in the Proton Exchange Membrane (PEM) fuel cells. The PFSI polymers, more proton conductive and stable at high temperatures, can dramatically increase the stability and lifetime of the PEM fuel cells, compared to widely used perfluorosulfuric acid (PFSA) polymers. This paper presents such a straightforward methodology to optimally construct a new nafion based diazonium PFSI monomer analogue, 2-diazonium 4-(trifluoromethyl) perfluoro-3, 6-dioxa-4-methyl-7-octene benzenesulfonylimide II. New approaches have been investigated to dramatically increase the percent yield for another monomer I, 4-diazonium perfluoro-3, 6-dioxa-4-methyl-7-octene benzenesulfonylimide. The thermal stability of the two monomer analogues then have been measured and compared. Another monomer analogue, 4-diazonium-3-fluoro perfluoro-3, 6-dioxa-4-methyl-7-octene benzenesulfonylimide III, has been attempted and discussed.

One diazonium (perfluoroalkyl) benzenesulfonimide monomer, perfluoro-3, 6-dioxa-4-methyl-7-octene benzenesulfonyl imide, has been synthesized from Nafion monomer for the first time. With trifluorovinyl ether and diazonium precursors, the partially-fluorinated diazonium PFSI monomer can be polymerized and will provide chemically bonding with carbon electrode in proton exchange membrane fuel cells. A systematic study of the synthesis and characterization of this diazonium PFSI monomer has been conducted by varying reaction conditions. The optimized synthesis method has been established in the lab.

Two new bis(perfluoroalkyl)arylsulfonyl imide monomers, which contain the aryl diazonium moiety and intramolecular zwitterionic fragment, have been designed and prepared for the first time from perfluoro(3-oxa-4-pentene)sulfonyl fluoride. As promising monomer candidates for high-performance proton exchange membrane fuel cell electrolytes, these two monomers have furnished perfluorinated electrolytes that include the polymers from perfluorinated sulfonic acid or perfluorinated sulfonimide monomers. The synthesis strategies and NMR analysis are summarized and discussed in details.

Objectives: This study aimed to examine the association of Per and Polyfluoroalkyl substances (PFAS) and markers of chronic inflammation and oxidative stress. Methods: Using data (n = 6652) from the National Health and Nutrition Examination Survey (NHANES) 2005–2012, generalized linear models were used to examine the association between PFAS and inflammatory (ferritin, alkaline phosphatase, C-reactive protein, absolute neutrophil count and lymphocyte count) and oxidative stress (serum bilirubin, albumin and iron) per unit exposure to PFAS while adjusting for covariates. Study participants were those ≥20 years of age. Outcome variables were markers of chronic inflammation and oxidative stress and exposure variables were PFAS. Resullts: Percentage change in Perfluorohexane sulfonic acid (PFHxS), Perfluorononanoic acid (PFNA), Perfluorooctanoic acid (PFOA), Perfluorooctane sulfonic acid (PFOS), and Perfluorodecanoic acid (PFDA) were all significantly associated with percentage increases in lymphocyte counts, beta (95% confidence interval); 0.04(0.02,0.05), 0.04(0.02,0.05), 0.05(0.03, 0.07), 0.04(0.03,0.05), 0.03(0.13,1.23) and with percentage increases in serum iron 0.07(0.05,0.09), 0.04(0.02,0.07), 0.10(0.07,0.12), 0.05(0.03,0.07), 0.04(0.02,0.06) and increased serum albumin 0.02(0.02,0.02), 0.02(0.02,0.03), 0.03(0.03,0.04), 0.02(0.017, 0.025), 0.01 (0.01, 0.05). Only PFHxS, PFNA, PFOA and PFOS were associated with percentage increases in serum total bilirubin 0.04(0.03,0.05), 0.02(0.00,0.03), 0.06(0.04,0.08), 0.03(0.02,0.05). Similar results were obtained for categorical quintile analysis with PFOA showing a significant trend (P < 0.001) with lymphocyte count, serum iron, serum total bilirubin and serum albumin. Trend for neutrophil count was not significant (p = 0.183). Conclusion: Per and Polyfluoroalkyl substances are associated with markers of chronic inflammation and oxidative stress. Increased exposure leads to increase in serum concentration of these markers meaning these chemicals are associated with both chronic inflammation and oxidative stress.