Showing papers on "Sodium metavanadate published in 2001"
TL;DR: In this paper, a ring-opening polymerization of cyclic metavanadates arising from co-ordination expansion favored by protonation or vanadium reduction was proposed.
69 citations
TL;DR: The interaction of sodium metavanadate and VOCl3 with ascorbic acid, one of the possible natural reducing agents of vanadium(V) to oxovanadium(IV), has been investigated and three new VO2+ complexes could be isolated as microcrystalline powders.
Abstract: The interaction of sodium metavanadate and VOCl3 with ascorbic acid, one of the possible natural reducing agents of vanadium(V) to oxovanadium(IV), has been investigated. Three new VO2+ complexes could be isolated as microcrystalline powders. One of them, of composition K1.5Na0.5[VO(HAsc)(OH)3], contains ascorbic acid as a monodentate ligand. In the other two, K[VO(Diketo)(OH)] x H2O and Na3[VO(Diketo)2(OH)], the enolized form of 2,3-diketogulonic acid (one of the oxidation products of ascorbic acid), acts as a bidentate ligand. The complexes were characterized by means of electronic (absorption and reflectance) and infrared spectroscopy and magnetic susceptibility measurements. Their thermal behavior was investigated by thermogravimetric and differential thermal analyses. The interest of the investigated system in relation to vanadium detoxification is also discussed.
22 citations
TL;DR: In this paper, an investigation was carried out under the conditions of optimization of the synthesis of NaVO 3 and Cl 2 from NaCl and V 2 O 5 in the presence of atmospheric oxygen.
Abstract: An investigation was carried out under the conditions of optimization of the synthesis of NaVO 3 and Cl 2 from NaCl and V 2 O 5 in the presence of atmospheric oxygen. The research was performed in the temperature range 623-873 K, for a 1-8 h time duration. The influence of the oxygen excess on the reaction yield was investigated.
12 citations
Patent•
20 Nov 2001
TL;DR: In this paper, the ammonium-containing mineral compounds are added to the mother solution to form saturated chloride salt solutions, which are further added to sodium metavanadate solution to achieve their summary concentration between 50 and 350 g/cu.
Abstract: inorganic compounds technology. SUBSTANCE: vanadium-containing industrial products are treated with alkali reagent, insoluble precipitate is separated and washed. Industrial water is combined with filtrate and ammonium-containing mineral compounds are added to combined solution to form ammonium metavanadate, which is separated from solution in the form of crystals by filtration, washed, dried, and calcined to give desired product. According to invention, addition of ammonium-containing mineral compounds to solution is preceded by dissolving therein sodium and/or potassium chloride (halite or selenite) to achieve their summary concentration between 50 and 350 g/cu. dm. In addition, mother solution after separation of ammonium metavanadate is divided in half and ammonium-containing mineral compounds, for example ammonium chloride or nitrate, are added to 20-50% mother solution to form saturated chloride salt solutions, which are further added to sodium metavanadate solution. EFFECT: increased degree of vanadium recovery and simplified detoxification of waste waters. 3 cl, 2 ex
6 citations
Patent•
10 Nov 2001
TL;DR: In this paper, a method was proposed where starting vanadium-containing waste, slag, and/or production middlings are treated with alkaline reagent, vanadium is selectively taken out from solid phase into solution, sodium metavanadate solution is separated from insoluble precipitate, inorganic ammonium salt is added to solution, resulting ammonium metavadate is crystallized, precipitated, filtered off and calcined to give commercial vanadium pentaoxide, after treatment with mineral acid solution, pulp is filtered, alkaline and acidic solutions combined
Abstract: metallurgy. SUBSTANCE: in a method, wherein starting vanadiumcontaining waste, slag, and/or production middlings are treated with alkaline reagent, vanadium is selectively taken out from solid phase into solution, sodium metavanadate solution is separated from insoluble precipitate, inorganic ammonium salt is added to solution, resulting ammonium metavanadate is crystallized, precipitated, filtered off and calcined to give commercial vanadium pentaoxide, after treatment with alkaline solution and separation of solution from precipitate, the latter is additionally treated with mineral acid solution, pulp is filtered, alkaline and acidic solutions combined, refiltered, divided into two parts, of which one part is supplemented by alkaline reagent and the other by mineral acid. Alkaline and acidic solutions are further reused for treatment of precipitate and are recycled until vanadium concentration in combined solution arrives at a value within a range of 15 to 100 g/cu.dm. More particularly, consecutive treatment of vanadium-containing raw material is carried out with sodium hydroxide solution and hydrochloric acid solution at their concentrations between 20 and 120 g/cu.dm and temperature 80-90 C, liquid-to-solids ratio varying between 4 and 8 and solid-to-liquid phase contact time between 0.5 and 1 h. Combination of vanadium-containing alkaline and acidic solutions is carried out under mutual neutralization conditions until final pH value of combined solution (pulp) reaches 5-9. EFFECT: increased vanadium recovery degree. 3 cl, 2 ex
1 citations