Reactive Fluorine Compounds

Abstract

Human activities have significanty increased the atmospheric concentrations of various compounds of fluorine. The input of such compounds into the environment is expected to grow rapidly in the future. Their environmental fate and impact should thus be carefully assessed. Compounds of fluorine are covered by this chapter if they do not contain other halogens and exhibit at least some economic or environmental relevance. Here, these substances are divided into the following groups: hydrofluorocarbons, perfluorocarbons, further organic fluorine compounds, long-and short-lived inorganic fluorine compounds. Their respective environmental relevance is discussed with special attention to the issues of "global warming","ozone depletion" and to their and their degradation products' toxic effects on the biosphere. A revised picture of the natural geochemistry of atmospheric fluorine is sketched including volcanic emissons, mineral dust, biomass burning, the release from sea-salt aerosol and the degassing of natural tetrafluoromethane. This natural situation is then compared with the anthropogenically disturbed case and a projected scenario for the year 2050.

Volcanic Formation of Halogenated Organic Compounds

“…The biggest part of atmospheric hydrogen chloride and hydrogen bromide now originates from sea salt volatilisation, but still some 0.5 -10 % of the total atmospheric HCl source strength are emitted directly from volcanoes. Inorganic fluorine emissions from volcanoes are among the biggest source for fluorine emitted into the atmosphere [4]. Table 1 compares volcanic emission rates of hydrogen halides with other major global sources.…”

Latitudinal and Size Segregated Compositional Variability of Aerosols over the Indian and Southern Ocean during 2010 Austral Summer

“…A noticeable observation is that the graphical variation of F -and NO 3 -is similar to an anthropogenic tracer nssSO 4 2-as well as to a marine tracer Cl -with their highest concentrations at S3 (11°S) and S5 (35°S). Many authors have regarded F -and NO 3 -as anthropogenic species in the marine atmosphere (Harnisch, 1999;Savoie et al, 2002). It is significant to note that the Cl -concentration also spikes at these two anthropogenically influenced sampling sites (S3 and S5) indicating significant anthropogenic influence in Cl -concentrations as well.…”

Rising Perfluorocyclobutane (PFC-318, c-C4F8) Emissions in China from 2011 to 2020 Inferred from Atmospheric Observations

“…With an atmospheric lifetime of 3200 years, PFC-318 has a 100 year time horizon global warming potential (GWP100) of 10,200 . Previously, PFC-318 emissions were assumed to be predominantly caused by its use for plasma etching in the semiconductor industry, but highly efficient abatement due to modern emission controls can reduce emissions from the semiconductor and microelectronics industry by up to 90%, making PFC-318 emissions from this industry likely relatively low . Another potentially noteworthy source of PFC-318 is the production of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) monomers. − The primary method for preparing TFE and HFP monomers is through the pyrolysis of hydrochlorofluorocarbon-22 (HCFC-22, CHClF 2 ).…”

“…In this process, PFC-318 is formed as a byproduct of the dimerization of TFE. By controlling the dimerization process of TFE, PFC-318 can be generated, and copyrolysis of PFC-318 and TFE may also lead to the formation of HFP or PFC-318. ,− , Mühle et al showed that PFC-318 emissions were highly correlated with the use or production of HCFC-22 feedstock, observed both on a global scale and within developing (Article 5 of the Montreal Protocol, A5) countries. Almost all global feedstock production of HCFC-22 is used to produce TFE and HFP, which are subsequently used to produce polytetrafluoroethylene (PTFE) and other fluorinated polymers and compounds, during which PFC-318 is formed as a byproduct and then likely emitted into the atmosphere.…”