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19F
Published in Guillaume Madelin, X-Nuclei Magnetic Resonance Imaging, 2022
Until World War II, there was no real commercial production of elemental fluorine, but as uranium enrichment is the largest application of fluorine gas, industrial production of fluorine began during the Manhattan Project as a step in the making of atomic bombs. Fluorine was used to produce uranium hexafluoride (UF6), which in turn was used to separate two uranium isotopes, 235U and 238U, from each other, and is still used nowadays to produce enriched uranium for nuclear power applications. Other commercial applications use fluorine compounds such as fluorite instead of pure fluorine (due to its difficult production), with about half of it used in steelmaking. Its very active chemistry makes fluorine useful in many products, such as polymers, pesticides, antibiotics and toothpastes (fluoride ion F− inhibits dental cavities). Compounds containing a carbon-fluorine (C–F) bond, called fluorocarbons or perfluorocarbons (PFCs), often have very high chemical and thermal stability and can be used as refrigerants, electrical insulation and cookware (such as Teflon). However, PFCs, as well as sulfur hexafluoride (SF6), are greenhouse gases with atmospheric lifetimes of more than 1000 years and global-warming potential. Though their concentrations are very small compared to the main greenhouse gas carbon dioxide, this very long lifespan in the atmosphere makes them important actors in the global greenhouse effect.
Inorganic Chemical Pollutants
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
Fluoride and fluorine come from fluorspar (CaF2). Sodium fluoride, sodium fluorosilicates (Na2SiF2), and fluoroacetates (FCH2COOH) are employed as insecticides, rodenticides, and delousing powders. Fluorine causes eye irritation and respiratory problems. Animal experiments have shown fluorine and fluoride only slightly damage pulmonary or renal tissues. The TLV value for fluorine is 1 ppm,889 but again, this level is unacceptable for the chemically sensitive.
Inorganic Chemicals in Drinking Water
Published in Joseph Cotruvo, Drinking Water Quality and Contaminants Guidebook, 2019
Fluorine is the most active halogen chemical and element 9 in the periodic table. Fluoride is its anion with a charge of −1. Fluoride is ubiquitous in the environment in water, rocks, plants, and animals in small amounts. It deposits in bone and in teeth as the fluorapatite mineral Ca5(PO4)3F—a very hard crystalline compound where the OH group in mineral apatite has been replaced by an F atom. Many types of toothpaste are fluoridated with sodium fluoride or stannous (tin II) fluoride.
Molybdenum-99 from Molten Salt Reactor as a Source of Technetium-99m for Nuclear Medicine: Past, Current, and Future of Molybdenum-99
Published in Nuclear Technology, 2023
Jisue Moon, Kristian Myhre, Hunter Andrews, Joanna McFarlane
So far, molecular fluorine81–85 (F2), hydrogen fluoride,86–89 and chlorine trifluoride84 (ClF3) are commonly used and suggested fluorinating agents. However, these reagents are highly corrosive and react with moisture, acids, and bases at room temperature. In the 2010s, McNamara et al.90,91 and Scheele et al.92 studied NF3 as a fluorination reagent to improve safety and thermal stability. Currently, NF3 is used on an industrial scale to etch with a form of plasma and clean microelectronic devices.93,94 This compound is not corrosive and is thermally stable to relatively high temperatures,91 and thermal studies indicate thermal decomposition in the temperature range of 800°C to 1200°C (Refs. 95 through 98).
Sorptive equilibrium profile of fluoride onto aluminum olivine [(FexMg1−x)2SiO4] composite (AOC): Physicochemical insights and isotherm modeling by non-linear least squares regression and a novel neural-network-based method
Published in Journal of Environmental Science and Health, Part A, 2018
Partha S. Ghosal, Ashok K. Gupta
Fluorine is the most electronegative and reactive element and rarely occurs in the elemental state. Fluorine is present in the groundwater naturally as fluoride, which acts as an essential micronutrient as well as a harmful contaminant depending upon the concentration.[1,2] Fluoridation of the drinking water is practiced as fluoride helps in the formation of bones and dental enamel in lower concentrations.[2,3] However, different level of dental, skeletal or crippling fluorosis has been reported at higher fluoride concentrations.[4] Fluorosis has become a global concern by affecting around 200 million people in more than 35 countries, including China, India, USA, Canada, South Africa, etc.[5,6] The World Health Organization has set up the permissible level of fluoride in the drinking water as 1.5 mg L−1.[5] In India, around 67 million people living in more than 20 states are under the fluoride attack.[4] The defluoridation of drinking water is one of the most significant challenges in the field of the environmental engineering.
Countermeasures against coal spontaneous combustion: a review
Published in International Journal of Coal Preparation and Utilization, 2022
In coal-fire areas, pollution and environmental degradation really threaten the health and life of local residents. In the Wuda coal fire area, gas monitoring carried out by the local Environmental Protection Department indicates that the concentrations of H2S, SO2 and other noxious gases in urban areas of Wuda are twice the national standard. The respiratory system may be seriously damaged by long-term exposure to these gases (Melody and Johnston 2015). With after-effects such as pigment deficiency, over-pigmentation, keratosis, and skin cancer, arsenic contained in coal fire discharge can result to chronic intoxication. Fluorine can contribute to fluorine osteopathy and even impair the ability of people to work (Finkelman 2004).