Disposal of fluorine

The overall reaction under controlled conditions provides a method for the disposal of fluorine by conversion to a salt ... 

Long, G., Apparatus for Disposal of Fluorine on a Laboratory Scale, Harwell, AERE, 1956... 

DesMarteau, D. D. et al., J. Amer. Chem. Soc., 1987, 109, 7194-7196 Fluorine is the most electronegative and reactive element known, reacting, often violently, with most of the other elements and their compounds (note the large MRH values quoted below). Handling hazards and disposal of fluorine on a laboratory scale are adequately described [1,2,3,4,5][6], and a more general review is also available [7], Safety practices associated with the use of laboratory- and industrial-scale fluorine cells and facilities have been reviewed [8], Equipment and procedures for the laboratory use of fluorine and volatile fluorides have been... 

Disposal of fluorine by neutralizing, scrubbing, or by other means may be subject to permitting by federal, state, or provincial regulations. Persons involved with disposal of fluorine should check with the environmental authorities having Jurisdiction to determine the applicability of permitting regulations to disposal activities. 

It is important to recognize that fluorinated surfactants are used only in small quantities, usually 10-100 times smaller than the amounts of hydrocarbon-type surfactants. Most fluorinated surfactant applications are in industry, where the handling and disposal of fluorinated surfactants can be controlled. Hence, a consumer is exposed much less to fluorinated surfactants than to hydrocarbon surfactants. It is reasonable to conclude that the toxicity of most fluorinated surfactants should not prohibit their proper use. Under usual application conditions, an exposure to fluorinated surfactants can be kept well within acceptable limits. 

Production Technology. Processes for extraction of P2O3 from phosphate rock by sulfuric acid vary widely, but all produce a phosphoric acid—calcium sulfate slurry that requires soHds-Hquid separation (usually by filtration (qv)), countercurrent washing of the soHds to improve P2O3 recovery, and concentration of the acid. Volatilized fluorine compounds are scmbbed and calcium sulfate is disposed of in a variety of ways. 

The abatement of fluorine emissions and disposal of by-product calcium sulfate from phosphoric acid plants are environmental concerns. 

Disposal. Fluorine can be disposed of by conversion to gaseous perfluorocarbons or fluoride salts. Because of the long atmospheric lifetimes of gaseous perfluorocarbons (see Atmospheric models), disposal by conversion to fluoride salts is preferred. The following methods are recommended scmbbing with caustic solutions (115,116) reaction with soHd disposal agents such as alumina, limestone, lime, and soda lime (117,118) and reaction with superheated steam (119). Scmbbing with caustic solution and, for dilute streams, reaction with limestone, are practiced on an industrial scale. 

The problems previously discussed are basically the same, with an added problem—disposal of excess fluorine. Studies are underway to find a safe, efficient way to resolve it. Ultimately, the use of DOR, previously discussed, is expected to replace fluorination and reduction. This would result in one process step, rather than two. In addition, the problems previously discussed would be eliminated. 

Dining interaction at ambient temperature in a bomb to produce poly (carbon monofluoride), admission of fluorine beyond a pressure of 13.6 bar must be extremely slow and carefully controlled to avoid a violently exothermic explosion [1], Previously it had been shown that explosive interaction of carbon and fluorine was due to the formation and decomposition of the graphite intercalation compound, poly (carbon monofluoride) [2], Presence of mercury compounds prevents explosion during interaction of charcoal and fluorine [3], Reaction of surplus fluorine with graphite or carbon pellets was formerly used as a disposal method, but is no longer recommended. Violent reactions observed when an exhausted trap was opened usually involved external impact on the metal trap, prodding the trap contents to empty the trap, or possibly ingress of moist air... 

It has also been observed281 that, for a number of fluorinated monosaccharides, geminal 19F- H coupling-constants for the pyranose series are larger when the fluorine substituent is axially rather than equatorially disposed. Exceptions to this generalization were subsequently found, as in the virtually identical value of/F 2, H-2 for peracetylated 2-deoxy-2-fluoro-a-D-gluco- and -manno-pyranosyl fluorides.71... 

Paulin Louyet, 1818-1850. Belgian chemist who investigated the compounds of fluorine. For his attempts to liberate fluorine, the Knox brothers placed at his disposal their costly fluorspar and platinum equipment His premature death was caused by continued exposure for about a decade to the toxic compounds of this element (69). Engraving by Danse, Brussels, 1851. 

Clearly the oil is a much cleaner fuel than the original coal, from the point of view either of the environmentalist or of the plant engineer concerned with fouling of steam and superheater tubes. The sulfur contents of the oils are 0.1-0.2%, which is acceptable, but the nitrogen contents are about 0.6%, which may cause undesired NOx emissions. Some of the more toxic elements, (mercury, selenium, fluorine, and cadmium) have not yet been determined in oil. It is not clear what will be done with the solid residue whether it will be disposed of as waste or whether its small carbon content, typically 20-50% depending on the... 

The alkali metals, as we have seen, are frisky little devils. If there is any doubt about this, watch potassium (K) burst into flame in the presence of air, or watch sodium (Na) react violently in water. As we learned in Chapter 4, there are some electron configurations that are very stable, mainly those having eight outermost electrons. The alkali metals have one outermost electron, which they are anxious to dispose of. These electrons are usually transferred to nonmetals, such as oxygen (O), chlorine (Cl), fluorine (F), and bromine (Br), with a release of energy that is predictable, pronounced, and unforgettable. 

Because the supply exceeds demand, the HCI generated often cannot be sold or reused even after purification. Although electrochemical fluorinations have been practiced commercially for many years, the main products of the reactions are typically perfluorocarbons since C-H bonds rarely survive. New methods, which avoid the need to feed chlorine and disposal of HCI are needed to prepare HCFCs and HFCs are obviously desirable. 

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