Search results
Results from the WOW.Com Content Network
The United States Environmental Protection Agency (EPA) defines PFAS in the Drinking Water Contaminant Candidate List 5 as substances that contain "at least one of the following three structures: R−CF 2 −CF(R')R", where both the −CF 2 − and −CF− moieties are saturated carbons, and none of the R groups can be hydrogen; R−CF 2 −O ...
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.
Fluorosurfactants (PFAS) reduce surface tension by concentrating at the liquid-air interface due to the lipophobicity of polyfluorocarbons. Chlorofluorocarbons are also perfluorinated compounds, many of which were formerly used as refrigerants ( Freon ) until they were implicated in ozone degradation .
Despite the nearly 15,000 Per- and Polyfluoroalkyl Substances (PFAS) known, the EPA singled out six in the first-ever federal limits for these chemicals in drinking water. PFAS, dubbed "forever ...
The bonds between carbon and oxygen or fluorine are strong. [3] Perfluoropolyethers are a type of PFAS. [4] The thermal and chemical stability of PFPEs along with a vapor–liquid equilibrium of 230 °C when mixed with the right composites make it a suitable candidate for vapor phase soldering technologies. [5]
The U.S. Environmental Protection Agency on Friday designated a pair of widely used industrial chemicals as hazardous substances under the country's Superfund program, accelerating a crackdown on ...
The Van der Waals radius of the fluorine substituent is only 1.47 Å, [1] which is shorter than in any other substituent and is close to that of hydrogen (1.2 Å). This, together with the short bond length, is the reason why there is no steric strain in polyfluorinated compounds.
Hydroxyl radicals are produced with the help of one or more primary oxidants (e.g. ozone, hydrogen peroxide, oxygen) and/or energy sources (e.g. ultraviolet light) or catalysts (e.g. titanium dioxide). Precise, pre-programmed dosages, sequences and combinations of these reagents are applied in order to obtain a maximum •OH yield.