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Trifluoroacetic Acid from CFC Replacements: An Atmospheric Toxicant Becomes a Terrestrial Problem
Published in James N. Seiber, Thomas M. Cahill, Pesticides, Organic Contaminants, and Pathogens in Air, 2022
James N. Seiber, Thomas M. Cahill
The second physicochemical property of TFA is that it is exceptionally stable under most environmental conditions. Since TFA is a highly oxidized molecule, it is expected to be resistant to degradation by oxidation. Additionally, the carbon–fluorine bond is one of the strongest single bonds found in organic molecules, which makes it more difficult to break. It also lacks any hydrogen atoms that are vulnerable to hydrogen abstraction. Therefore, degradation in the environment is expected to be very slow.
Activated Sludge Process for Refractory Pollutants Removal
Published in Maulin P. Shah, Removal of Refractory Pollutants from Wastewater Treatment Plants, 2021
Reyhan Ata, Gökçe Faika Merdan, Günay Yıldız Töre
The strong structure of carbon-fluorine bonds is the factor that makes perfluoroalkyl chains resistant to biodegradation and stabilize over wide temperature, pH, and pressure ranges. The persistence, toxicity, and bioaccumulation potential of certain perfluoroalkyl chain lengths of perfluoroalkyl carboxylic and sulfonic acids (PFCAs and PFSAs, respectively) have resulted in numerous phase-outs and bans worldwide. The introduction of PFOAs into the environment occurs through various mechanisms, such as the active use of fire-fighting surfactants, discharge from chemical production facilities (i.e., air emissions or wastewater), improperly treated wastewater, and the improper disposal of household products produced with PFAs. Studies have shown that PFOS can bioaccumulate in the human body by oral, inhalation, and dermal routes or by consuming contaminated seafood and drinking water. PFOS taken into the human body through diet can cause serious toxic effects such as liver toxicity, developmental toxicity, and immunotoxicity. It may also have negative effects on reproductive organs, cause endocrine disrupting effects, and increase the risk of breast cancer. Consequently, poly- and perfluoroalkyl substances (PFASs), which are not biodegradable due to their high thermal and chemical stability, are widely distributed in the environment, especially in the receiving aquatic environment (Saikat et al. 2013).
PFASs in Consumer Products
Published in David M. Kempisty, LeeAnn Racz, Forever Chemicals, 2021
Simona Andreea Ba˘lan, Qingyu Meng
PFAAs are perfluorinated substances in which fluorine atoms have replaced all hydrogen atoms attached to carbon atoms (except for those associated with functional groups). Due to the strength of the carbon-fluorine bond, these compounds are recalcitrant and extremely persistent in the environment. Examples include perfluoroalkyl carboxylic acids (PFCAs) such as perfluorooctanoate (PFOA), perfluoroalkyl sulfonic acids (PFSAs) such as perfluorooctane sulfonate (PFOS), perfluoroether carboxylic acids (PFECAs) such as GenX, and perfluoroether sulfonic acids (PFESAs) such as ADONA. PFAAs and some of their precursors are frequently subdivided into longer- and shorter-chain PFASs. The longer-chain PFSAs have six or more perfluorinated carbons; longer-chain PFCAs have seven or more perfluorinated carbons (OECD 2018).
A critical review on the bioaccumulation, transportation, and elimination of per- and polyfluoroalkyl substances in human beings
Published in Critical Reviews in Environmental Science and Technology, 2023
Yao Lu, Ruining Guan, Nali Zhu, Jinghua Hao, Hanyong Peng, Anen He, Chunyan Zhao, Yawei Wang, Guibin Jiang
Per- and polyfluoroalkyl substances (PFAS) are widely used in numerous industrial and commercial products due to their unique hydrophobic, oil-repellent, and high surface-activity properties (Evich et al., 2022). Over 1,400 individual PFAS are used in the industry in over 200 diverse applications, and PFAS can be found in various environmental matrices. The characteristics of carbon-fluorine bond make PFAS resistant to chemical and thermal degradation, which make them persistent in the environment and can enter the organism, causing potential human concerns and ecological risks (Wang et al., 2017). PFAS have been the focus of research in the field of environmental science since the early 2000s due to their wide presence in environmental and biological matrices and potential PBT (P: persistence; B: bioaccumulation; T: toxicity) properties (Evich et al., 2022; Lu, Liang, et al., 2019b; Wang et al., 2017). Perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS) as well as their salts and related compounds have been listed in the Stockholm Convention as new persistent organic pollutants (POPs) for management (Stockholm Convention, 2022). Additionally, long-chain perfluorocarboxylic acids (PFCAs), their salts, and related compounds are proposed for listing into the Stockholm Convention and are under review by the Persistent Organic Pollutants Review Committee (Stockholm Convention, 2021).
Recent progress in adsorptive removal of per- and poly-fluoroalkyl substances (PFAS) from water/wastewater
Published in Critical Reviews in Environmental Science and Technology, 2022
PFAS are a group of anthropogenic and environmentally persistent contaminants, which have been reported to be linked with reproductive and developmental problems, endocrine disruption and cancers (DeWitt, 2015). The synthesis and usage of PFAS dated back to 1960s (Pancras et al., 2016). These compounds possess a hydrophobic-oleophobic aliphatic alkyl chain with the hydrogen atoms either totally (per-) or partly (poly-fluoroalkyl) replaced by fluorine atoms (Moody & Field, 1999). The carbon-fluorine bonds are highly polar and strong (bond energy 110 kcal mol−1), rendering PFAS thermally and chemically stable (Ateia et al., 2019). These compounds are both hydrophilic and hydrophobic due to the functional hydrophilic group head and the perfluorinated tail, respectively. The amphiphilic property makes PFAS extremely useful for various technological applications such as waterproof and stainproof coating, photographic films, fabric protection, metal plating, surfactants for semiconductor etching, food packaging, lubricants, nonstick coatings, fire retardants, and aqueous film forming foams (AFFFs) (Fujii et al., 2007).
Novel methacrylate copolymers functionalized with fluoroarylamide; copolymerization kinetics, thermal stability and antimicrobial properties
Published in Journal of Biomaterials Science, Polymer Edition, 2021
The presence of fluorine atom in a molecule can make it a pharmacophore. Due to the stability of the carbon-fluorine bond, the release time of many fluorine-containing drug molecules in metabolism is prolonged. With fluorination, the half-life of the drug is extended, and the dosing-activation times are increased. Besides, fluorinated organic molecules are very stable due to the strong carbon-fluorine bonds they contain. This property generally increases the bioavailability of a drug due to increased cell membrane penetration. Also, because the polar C-F bond is more hydrophobic than the C-H bond, fluorinated pharmacophores exhibit a lipophilic effect. This effect generally increases the release of a drug due to increased cell membrane penetration. The Fluorine atom is found in the structure of mineralocorticoids, a class of drugs that increase blood pressure, fludrocortisone, an anti-inflammatory drug, and dexamethasone and triamcinolone, which are among the strongest corticosteroid drugs [42, 43]. The significant effect of synthesized polymers with fluorine atoms on bacteriums is a promising advance in polymer science. It is possible to say that this effect is caused by the pharmacophore fluorine atoms in the side branch.