Vanadic acid ammonium salts

SYNS AMMONIUM METAVANADATE pOT) RCRA WASTE NUMBER PI 19 VANADIC ACID, AMMONIUM SALT... 

VANADIC ACID, AMMONIUM SALT see ANY250 VANADIC ACID, MONOSODIUM SALT see SKPOOO VANADIC ACID, POTASSIUM SALT see PLK810 VANADIC(II) ACID, TRISODIUM SALT see SIY250 VANADIC ANHYDRIDE see VDUOOO VANADIC OXIDE see VEAOOO VANADIO, PENTOSSIDO di (ITALIAN) see VDUOOO VANADIUM see VCPOOO... 

P112. . Tetranitromethane (R) P119. . Vanadic acid, ammonium salt... 

The ammonium salts of vanadic acid and vanadium pentoxide have been Hsted as toxic constituents in soHd wastes under the Resource Conservation and Recovery Act (27). 

For direct precipitation of vanadium from the salt-roast leach Hquor, acidulation to ca pH 1 without the addition of ammonia salts yields an impure vanadic acid when ammonium salts are added, ammonium polyvanadate precipitates. The impure vanadic acid ordinarily is redissolved in sodium carbonate solution, and ammonium metavanadate precipitates upon addition of ammonium salts. Fusion of the directly precipitated ammonium salts can yield high purity V20 for the chemical industry. Amine solvent extraction is sometimes used to recover 1—3 g/L of residual V20 from the directly precipitated tail Hquors. 

Arsenites may also be determined by this procedure but must first be oxidised by treatment with nitric acid. Small amounts of antimony and tin do not interfere, but chromates, phosphates, molybdates, tungstates, and vanadates, which precipitate as the silver salts, should be absent. An excessive amount of ammonium salts has a solvent action on the silver arsenate. 

Salts of Vanadic Acid. Pour 3-4 ml of a sodium vanadate solution into each of two test tubes. Add to one of them a silver nitrate solution, and to the other a saturated ammonium chloride solution. Write the equations of the reactions. 

Lead Metavanadate, Pb(VOg)2.—Acid solutions of vanadates on being treated with lead salts give rise to yellow basic vanadates the composition of which varies with the conditions. The precipitation of normal lead vanadate is, therefore, difficult. It has been accomplished by the addition of lead acetate to ammonium metavanadate solution in the presence of acetic acid.2 The lead precipitates contain all the vanadic acid originally present in solution, and precipitation of vanadates with lead salts has, therefore, been employed for the quantitative estimation of vanadium.3 The mineral deschenite consists chiefly of lead metavanadate a portion of the lead is, however, frequently replaced by zinc.4... 

One of the simplest methods of preparation is by decomposition of a thermally unstable compound. The nitrate or chloride is often preferred, sulphates tend to decompose at higher temperatures. Where the presence of residual traces of anion is to be avoided, the metal salts of organic acids are particularly useful. Formates, oxalates, acetates etc, decompose at low temperatures and often reduce the metal at the same time. For the preparation of catalysts from anions, the ammonium salt is frequently used. Metallic salts of complex acids can be used as a source of metal oxide mixtures. Decomposition of the appropriate chromate, tungstate, molybdate or vanadate will produce the mixed oxide. 

Supported vanadium oxide catalysts may be prepared by either mixing powdered pumice with a solution of ammonium vanadate and subsequently drying, by soaking pumice in a gum solution and then shaking with ammonium vanadate powder, by impregnating porous material with a colloidal solution of vanadic acid stabilized with starch, blood, etc., or by precipitating the oxide on the porous support from solutions of the salt.20... 

A large number of inorganic layer crystals such as micas, sodium silicates, niobate, uranate, vanadate, titanate, zirconium phosphate, graphitic acids, crystalline silicic acids, vanadium oxyhydrate, calcium phosphoric acid esters, and titanium disulfide develop alkyl crystals between their rigid crystal layers by ion exchange with, for example, alkyl ammonium salts and by intercalation inorganic... 

Chromates, vanadates, and cerium salts give colour reactions with the reagent and should therefore be absent. Iron salts give a yellow colour with hydrogen peroxide, but this is eliminated by the addition of concentrated phosphoric acid. Fluorides bleach the colour (stable [TiFa] ions are formed), and large amounts of nitrates, chlorides, bromides, and acetates as well as coloured ions reduce the sensitivity of the test. A decrease in the intensity of the yellow colouration upon the addition of ammonium fluoride indicates the presence of titanium. 

This complex is prepared by reducing the alkali vanadate (formed from the ammonium salt) by hydrazine hydrate in acetic acid. The addition of potassium oxalate in presence of ethanol precipitates the complex. 

Weiss [1963] has summarized the very extensive work of himself and his collaborators (Weiss and Hofmann [1951], Weiss et al. [1956, 1956a], Weiss [1958], Weiss et al. [1959]) on alkylammonium-vermiculite complexes. They find that the complexes are formed in simple stoichiometric proportions. Some estimate of the charge density of the silicate layers can be made from X-ray diffraction measurements of the interlayer distance of the pure n-alkyl-ammonium derivatives. Comparison is made with a variety of other minerals (silicates vanadates, phosphates, uranyl salts), which form similar organic complexes. Measurements have been made of the extra swelling produced when alkylammonium-silicates are treated with various liquids, viz., water and aqueous electrolyte solutions, alcohols, aldehydes, carboxylic acids, nitrocompounds, phenols, nitrogen bases, esters, ethers, ketones, halogen compounds, and hydrocarbons. 

Vanadium usually is recovered from its ores by one of two processes, (1) leaching raw mineral with hot dilute sulfuric acid, and (2) roasting ore with common salt to convert vanadium into water soluble sodium vanadates. In the sulfuric acid leaching process, vanadium is extracted from acid leach liquors by solvent extraction with an aliphatic amine or an alkyl phosphoric acid in kerosene. The organic solvent extract then is treated with an aqueous solution of ammonia in the presence of ammonium chloride to convert vanadium into ammonium metavanadate. Alternatively, the organic extract is treated with dilute sulfuric acid or an aqueous solution of soda ash under controlled conditions of pH. Vanadium is precipitated from this solution as a red cake of sodium polyvanadate. 

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