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Per- and polyfluoroalkyl substances (also PFAS, [1] PFASs, [2] and sometimes referred to as "forever chemicals" [3] [4]) are a group of synthetic organofluorine chemical compounds that have multiple fluorine atoms attached to an alkyl chain; there are 7 million such chemicals according to PubChem. [5]
Perfluorobutanoic acid (PFBA) is a perfluoroalkyl carboxylic acid with the formula C 3 F 7 CO 2 H. As the perfluorinated derivative of butyric acid , this colourless liquid is prepared by electrofluorination of the corresponding butyryl fluoride.
Trifluoroacetic acid is a widely employed acid, used for example in the synthesis of peptides.Its esters are useful in analytical chemistry. Longer-chain perfluoroalkyl carboxylic acids, e.g. with five to nine carbons, are useful fluorosurfactants and emulsifiers used in the production of polytetrafluoroethylene (Teflon) and related fluoropolymers.
It is used as a surfactant and protective coating in applications such as aqueous firefighting foams, textile coating, metal plating and in polishing agents. [ 5 ] [ 6 ] PFHxS production is slowly being phased out since 3M stopped producing C 6 fluorotelomers in 2002, but production by other companies may be ongoing. [ 4 ]
Perfluorooctanesulfonic acid is usually used as the sodium or potassium salts. PFOS was the key ingredient in Scotchgard, a fabric protector made by 3M, and numerous stain repellents. PFOS, together with PFOA, has also been used to make aqueous film forming foam (AFFF), a component of fire-fighting foams, and alcohol-type concentrate foams.
Perfluorodecanoic acid (PFDA) is a fluorosurfactant and has been used in industry. [2] PFDA is a member of the group of polyfluoroalkyl substances (PFAS), more specific is it also a perfluoroalkyl acid (PFAA). PFAS, like PFDA, are man-made and are not naturally occurring in nature.
In today's puzzle, there are seven theme words to find (including the spangram). Hint: The first one can be found in the bottom half of the board. Here are the first two letters for each word:
Remediation of per- and polyfluoroalkyl substances refers to the destruction or removal of per- and polyfluoroalkyl substances (PFASs) from the environment. PFASs are a group of synthetic organofluorine compounds, used in diverse products such as non-stick cookware and firefighting foams, that have attracted great concern as persistent organic pollutants.