Fluoride iron

Ammonium bifluoride is used as a sour or neutralizer for alkalies in commercial laundries and textile plants. Treatment also removes iron stain by forming colorless ammonium iron fluorides that are readily rinsed from the fabric (17). 

Monel and nickel are the preferred materials of constmction for cylinders and deHvery systems however, copper, brass, steel, and stainless steel can be used at room temperature, providing that these metals are cleaned, dried, and passivated with a fluoride film prior to use. Studies have shown that fluorine passivation of stainless steel and subsequent formation of an iron fluoride layer prior to WF exposure prevents reaction between the WF and the stainless steel surface (23). 

Fluor-, of or combined with fluorine, fluoro-, fluo-, fluoride of (see instances following),. ammonium, n. ammonium fluoride, -an-thenchinon, n. fluoranthenequinone. -anti-mon, n. antimony fluoride, -arson, n. arsenic fluoride, -baryum, n. barium fluoride, -benzol, n. fluorobensene, fluobenaene. -bor, n. boron fluoride. -borsMure, /. fluo-boric acid. -brom, n. bromine fluoride, -chrom, n. chromium fluoride, -eisen, n. iron fluoride. 

Thermal dissociation produces ammonium fluoride and ammonia at elevated temperatures products contain ammonia and hydrogen fluoride. It forms a colorless double salt, ammonium iron fluoride SNEUF FeFs, with iron, a reaction of commercial apphcation for removing stains from fabric. It reacts with many metal oxides at elevated temperatures forming double fluorides ... 

Iron Fluoride. See Ferric Fluoride in this Section... 

Flame retardants - [TEXTILES-FINISHING] (Vol 23) - [ALUMENUMCOMPOUNDS - INTRODUCTION] (Vol2) -antimony as [ANTIMONY AND ANTIMONY ALLOYS] (Vol 3) -antimony compds as [ANTIMONY COMPOUNDS] (Vol 3) -antimony compds as [ANTIMONY COMPOUNDS] (Vol 3) -based on ammonium sulfamate [SULFAMIC ACID AND SULFAMATES] (Vol 23) -bromine in [BROMINE] (Vol 4) -in electronic applications [PACKAGING - ELECTRONIC MATERIALS] (Vol 17) -iron fluoride in mfg of [FLUORINE COMPOUNDS, INORGANIC - IRON] (Vol 11) -nickel compounds as [NICKEL COMPOUNDS] (Vol 17) -phosphorus for [PHOSPHORUS] (Vol 18) -polycarbonates in [POLYCARBONATES] (Vol 19) -from propylene oxide [PROPYLENE OXIDE] (Vol 20) -for rubbers [RUBBERCHEMICALS] (Vol 21) -use m electrical connectors [ELECTRICAL CONNECTORS] (Vol 9)... 

Iron halides react with halide salts to afford anionic halide complexes. Because iron(III) is a hard acid, the complexes that it forms are most stable with F and decrease in both coordination number and stability with heavier halides. No stable I complexes are known. [FeF5(H20)]2 is the predominant iron fluoride species in aqueous solution. The [FeF6]3 ion can be prepared in fused salts. Whereas six-coordinate [FeClJ3 is known, four-coordinate complexes are favored for chloride. Salts of tetrahedral [FeClJ can be isolated if large cations such as tetraphenylarsonium or tetraalkylammonium are used. [FeBrJ is known but is thermally unstable and disproportionates to iron(II) and bromine. Complex anions of iron(II) halides are less common. [FeClJ2 has been obtained from FeCl2 by reaction with alkali metal chlorides in the melt or with tetraethylammonium chloride in deoxygenated ethanol. 

Hydrofluoric acid causes two types of corrosion, direct corrosion, in which iron fluoride is formed, and stress corrosion, in which the metal cracks. Electrolytic corrosion can also take place when the acid becomes diluted with water and two dissimilar metals or carbon are used. Because of the possibility of stress corrosion, all vessels in acid service must be stress-relieved. Monel is also subject to stress corrosion and must be stress-relieved. Care must be taken in stress-relieving Monel that sulfur or sulfur compounds do not come in contact with the Monel either before or during the heat treatment. 

The crystal structure of cesium iron fluoride, Cs3Fe2F9, comprises a packing of binuclear face-sharing octahedral FeiF - units and Cs+ ions. With a = 634.7(1), c = 1480.5(3) pm and Z = 2, the locations of the atoms and the Fe2Fg anion are shown in the following table ... 

Typically, the ammonium or hydronium form of the zeolite is slurried in water and reacted with the requisite amount of the ammonium fluoride salt of either iron or titanium. Given the sparingly soluble nature of ammonium fluotitanate, the (NH )2TiF6 can be added to the zeolite slurry in slurry form, or directly as salt. Alternatively, the iron may be added to the zeolite slurry as a slurry of the ammonium fluoride salt crystals in water, or the FeF3 crystals can be mixed with a water solution of ammonium fluoride or ammonium bifluoride, such that the composition of the treatment solution contains the stoichiometry of the ammonium iron fluoride salt, (NH4)3FeF6. The (NH )3FeF6 crystals can also be added directly to the zeolite slurry. The amount of either metal ammonium fluoride salt added during the reaction is determined by the desired product composition and the anticipated completeness of the reaction. 

Chemical analyses and physical property measurements made on the starting materials and the products of the ammonium fluotitanate reactions are shown in Table 2. The analytical data for the products of the iron ammonium fluoride reaction are shown in Table 3. Following treatment, the various zeolite products contained up to 16.1 wt.% Ti02 in the zeolites treated with ammonium fluotitanate, and up to 16.9 wt.% Fe203 in the zeolites treated with ammonium Iron fluoride. X-ray powder diffraction intensity is decreased in the substituted products, but retention of oxygen and water adsorption capacity indicates that pore volume has been retained. No extraneous peaks due to other crystalline phases were observed in the X-ray powder diffraction patterns of well washed products. 

Table 3. Chemical Analyses and Physical Property Measurements of the Starting Zeolites and the Products of the Ammonium Iron Fluoride Reaction...

Sufficient ammonium iron fluoride salt was added to the NH4Y to replace 55% of the framework A1 in the Y zeolite. The LZ-224 product contained 16.9 wt.% Fe203. The product was 48% dealuminated with an apparent value of 95% substitution of Fe into the dealuminated sites. This value is inflated due to the fact that iron Is also exchanged into the normal cation positions as well. The color of the LZ-224 product was brown, indicating the presence of the Fe cations. The normal cation equivalent,... 

Hydrofluoric acid — (HF) A solution of hydrogen fluoride in water. The pure hydrogen fluoride is characterized by Mw of 20.0063 gmol-1 m.p. -83.55 °C (1 atm) b.p. 19.5 °C (latm). When concentrated, this colorless fuming liquid is extremely corrosive and can dissolve almost all inorganic oxides such as silicate compounds or oxides of metals like stainless steel, aluminum, and uranium however, it can be stored in casted iron bottles because a corrosion-resistant iron fluoride layer protects the metal. It is used for several purposes such as the preparation of titanium oxide nano tube arrays [i], silicon nanoparticles [ii] and electrochemical etching of silicon [iii], electrochemical deposition of lithium [iv], etc. 

Sualitative analysis of the screw heads did show the corroded film on Le screws was the metal fluorides. New screws were used in each run, and the necessary thermal corrections were made on the data for this side reaction. The deficiency of HF was used to make these corrections which amounted to the formation of roughly 0.0015 mole of iron and chromium fluorides. Since the AHf° of iron and chromium fluorides are nearly the same, the correction was made assuming only the formation of iron fluoride (AH/0 = —177.8 kcal./mole). As an additional check, an OF2-H2 run was made with the stainless steel screws replaced by nickel-... 

S. BAIRD (Texas Instruments) I would like to suggest an experiment. You believe that the iron fluoride complex sets down at a kink and stops its motion. Further insight to this mechanism could be gained by substituting other transition elements that form stable complexes with fluorine perhaps one or more of them will be too big to fit into the kink. Another way would be to use other complexing agents than fluorine for the iron in order to vary the size of the ion setting down at the kink. 

Platinum is attacked only slowly by fluorine. Copper and steel can be used as containers lor the gas they are attacked by it, but become coated with a thin layer of copper fluoride or iron fluoride which then protects them against further attack. Fluorine was first made in 1886 by the French chemist Henri Moissan (1852-1907), by the electrolysis of a solution of potassium fluoride, KF, m liquid hydrogen fluoride, HF. In recent years methods for its commercial production and transport (in steel tanks) have been developed, and it is now used in chemical industry in moderate quantities. 

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