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hydrofluoric acid silica separation

    Re-generation of hydrofluoric acid and selective ...

    Nov 25, 2004  Re-generation of hydrofluoric acid and selective separation of Si(IV) in a process for producing ultra-clean coal ... in coal has been developed. The technique first uses aqueous hydrofluoric acid (HF) to react with aluminosilicates and quartz to form fluoride complexed Al and Si species in solution. ... Following silica precipitation, the 250 ...

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    US5242670A - Method for hydrofluoric acid digestion of ...

    A process for hydrofluoric acid digestion of inorganic silica/alumina matrix material for the production of silicon tetrafluoride and aluminum fluoride comprises the initial step of reacting the matrix material with hydrofluoric acid, to form silicon tetrafluoride gas and a solution/slurry containing aluminum fluoride, undigested oxides, and additional soluble and insoluble fluoride

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    Method for hydrofluoric acid digestion of silica/alumina ...

    The process for hydrofluoric acid digestion of silica/alumina matrix material for the production of silicon tetrafluoride and aluminum fluoride and other heavy metals involves the following general equations: I. Separation silica/alumina matrix material as SiF 4 (g) and AlF 3: SiO 2 /Al 2 O 3 +10HF SiF 4 (g) +2AlF 3 (aq) +5H 2 O . II.

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    Rapid, Micro-Methods to Estimate Plant Silicon Content by ...

    acid (36%), 1 v of concentrated hydrofluoric acid (49%), and 18 v of distilled water. For the experiment on the effect of the concentration of hydrofluoric acid on silica dissolution, solutions with 2-3 M HF were pre- pared. Although these solutions, thus diluted, are not volatile, contact with the skin should be avoided. The

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    Method for hydrofluoric acid digestion of silica/alumina ...

    The process for hydrofluoric acid digestion of silica/alumina matrix material for the production of silicon tetrafluoride and aluminum fluoride and other heavy metals involves the following general equations: I. Separation silica

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    Rapid, Micro-Methods to Estimate Plant Silicon Content by ...

    acid (36%), 1 v of concentrated hydrofluoric acid (49%), and 18 v of distilled water. For the experiment on the effect of the concentration of hydrofluoric acid on silica dissolution,

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    The determination of silica by conway's microdiffusion ...

    Tlie addition of hydrofluoric acid to an aqueous acidic silica-containing solution converts the silica to its fluoride compounds; it is assumed tliat silica volatilizes as silicon tetrafluoridc, this

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    Precipitation of Hydrated Silica From Spent Hydrofluoric ...

    Summary. Recent studies have shown that the reaction of clay with hydrofluoric (HF) acid is more complex than was earlier believed. It has been found that fluosilicic acid, generated during initial dissolution of clay, reacts with additional clay, extracting aluminum and depositing hydrated silica.

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    Hydrofluoric acid HF - PubChem

    Hydrofluoric acid is an irritant to the mucosa of the upper and lower portions of the respiratory tract. As in ocular tissues, concentrations as low as 5 mg/L (5 ppm) may produce irritation to the nasal mucosa. When hydrofluoric acid

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    A hydrofluoric acid-free method to dissolve and quantify ...

    May 28, 2019  An often-insurmountable obstacle for SiO2-NP fate and hazard research is the challenging analytics of solid particulate silica species, which involves toxic and corrosive hydrofluoric acid

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    Quartz separation with HF

    An initial heavy liquid separation will remove garnet and muscovite (as well as most other mafic ... Contact with hydrofluoric acid is extremely dangerous. Burns from small amounts of concentrated HF (48-50%) can be lethal. ... Any fluoride or acid

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    Hydrofluoric acid (HF) reacts with silicon dioxide to ...

    Dec 30, 2015  Start by writing the chemical formulas of the reactants, which are . hydrofluoric acid, #"HF"#; silicon dioxide, #"SiO"_2#; Do the same for the products, which are . silicon

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    Hydrofluoric acid - Wikipedia

    Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water.Solutions of HF are colourless, acidic and highly corrosive.It is used to make most fluorine-containing compounds; examples

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    WO2014036575A1 - Purification and silica removal from used ...

    A process for purifying contaminated, acidic, inorganic pickling wastewaters from carbon steel pickling, in particular those based on hydrochloric acid solutions, but also those based on mixed acids, principally those of a nitric acid-hydrofluoric acid

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    HYDROFLUORIC ACID

    Hydrofluoric acid is hydrogen fluoride (HF) in aqueous solution. It is a colorless fuming, liquid that comes in different industrial grades depending on the concentration of hydrogen fluoride which has a molecular weight of 20.01. The concentrated, fuming acid

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    Solved: Hydrofluoric Acid Is Used To Etch Glass By Reactin ...

    Hydrofluoric acid Is used to etch glass by reacting with the silica, SiO_2, in the glass to produce gaseous silicon tetrafluoride and liquid water. What is the mass of the piece of glass (silica)

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    A novel separation and preconcentration method for traces ...

    The coagulated silica and solution were separated by centrifugation, and the silica was then treated with hydrofluoric and perchloric acids. The residue was taken up in dilute nitric acid and subjected to ICP-AES to determine manganese, cobalt, zinc and cadmium. The proposed method was successfully applied to analysis of river-water.

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    Precipitation of Hydrated Silica From Spent Hydrofluoric ...

    Summary. Recent studies have shown that the reaction of clay with hydrofluoric (HF) acid is more complex than was earlier believed. It has been found that fluosilicic acid, generated during initial dissolution of clay, reacts with additional clay, extracting aluminum and depositing hydrated silica.

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    Preparation of silica nanospheres and porous polymer ...

    Aug 08, 2012  In particular, silica nanospheres were produced by manipulating the mixing ratio of polymer to silica sol. The size of silica beads was gradually changed from micro- to nanoscale, depending on the polymer content. At the same time, porous polymer membranes were generated by removing the silica component with hydrofluoric acid.

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    A hydrofluoric acid-free method to dissolve and quantify ...

    May 28, 2019  An often-insurmountable obstacle for SiO2-NP fate and hazard research is the challenging analytics of solid particulate silica species, which involves toxic and corrosive hydrofluoric acid (HF).

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    Precipitation of Hydrated Silica From Spent Hydrofluoric ...

    Precipitation of hydrated silica from spent HF acid hasbeen the subject of extensive investigation. Theconditions under which Si(OH)4 precipitation occurs havebeen established, and there is little doubt that most of the silicon dissolved by HF acid during acidizing ofargillaceous sandstone is precipitated as hydrated silica beforethe spent acid can be recovered from the formation.

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    Reaction of High‐Silica Optical Fibers with Hydrofluoric Acid

    Optical fibers are used to determine the etching rate and activation energy of silica and high‐silica glasses in hydrofluoric acid. The reaction is linearly dependent on time and transport controlled. Citing Literature. Number of times cited according to CrossRef: 6.

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    EVALUATION OF WASTE SILICA PRECIPITATED IN THE

    Waste silica was sampled directly from production of hydrofluoric acid, involving decomposition of fluosilicic acid using sulphuric(VI) acid. The silica was subjected to purification by removal of post-production contaminations (HF and H2SiF6 in particular). Since hydrofluoric acid and fluosilicic acid are well soluble in water, the

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    Safe Use of HF - Chemistry

    Hydrofluoric acid etches glass, due to the strong bond formed between fluoride anions and the silicon molecules in glass. HF will also react with glazes, enamels, pottery, concrete, rubber, leather, many metals (especially cast iron) and many organic compounds. Hydrogen gas, which may pose an explosion hazard, is generated upon reaction with ...

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    Anisotropic Etching of Pyramidal Silica Reliefs with Metal ...

    Anisotropic etching behavior in completely amorphous layers of silicon dioxide in combination with purely isotropic hydrofluoric acid as etchant is an unexpected phenomenon. The work presents practical exploitations of this new process for self‐perfecting pyramidal structures. It can be used for textured silica or glass surfaces.

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    HYDROFLUORIC ACID

    Hydrofluoric acid is hydrogen fluoride (HF) in aqueous solution. It is a colorless fuming, liquid that comes in different industrial grades depending on the concentration of hydrogen fluoride which has a molecular weight of 20.01. The concentrated, fuming acid contains about 70% hydrogen fluoride and is highly corrosive and toxic.

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    CDC Facts About Hydrogen Fluoride (Hydrofluoric Acid)

    Facts About Hydrogen Fluoride (Hydrofluoric Acid) Related Pages. FACT SHEET. What hydrogen fluoride is. Hydrogen fluoride is a chemical compound that contains fluorine. It can exist as a colorless gas or as a fuming liquid, or it can be dissolved in water.

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    Hydrofluoric acid, Zirconium Crucibles suppliers in South ...

    Fused silica/quartz is completely unaffected by all halogens and acids regardless of temperature or concentration with the exception of hydrofluoric and phosphoric acids. The latter affects fused silica only at high temperatures and it is possible, therefore to concentrate phosphoric acid successfully in silica vessels.

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    19 questions with answers in HYDROFLUORIC ACID Science topic

    Jan 21, 2021  P-SI(100) substrates had SiO2 layers removed by etching with Hydrofluoric acid. Onto these etched substrates, a 20nm ZnO interface layer was deposited by Rf sputtering, followed shortly a 300nm ...

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    ACIDS, INORGANIC 7903

    The method was field-evaluated at two electroplating facilities using side-by-side silica gel tubes and bubblers. The method was evaluated for hydrofluoric acid in 1983 using the silica gel tubes and impingers [7]. Recovery based on impinger collection was 106% with ˆ : rT. of 0.116. The capacity of the silica gel sampler for HF was 820 µg.

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