White Tungstic Acid
White tungstic acid is one of different types of tungstic acid. Chemical formula of tungstic acid is mWO3•nH2O. It has various composition forms which are all composed by WO3 and H2O in different ratio and become polyepoxy compound such as yellow tungstic acid, white tungstic acid and metatungstic acid.
White tungstic acid appearance is white crystalline powder, it is active, optical sensitive and can be easy reduced. It can be produced by adding dilute nitric acid into sodium tungstate solution or decomposing peroxide tungstate solution by nitric acid, white tungstic acid powder can be obtained, it is less active than microcrystalline structure white tungstic acid. White tungstic acid can be used to prepare tungsten containing isopolyacid and heteropolyacid, also tungsten carbide, low metal cluster compounds of tungsten, petroleum catalyst, coloring agent and lubricant.
There has been study for adding sodium tungstate solution in dilute nitric acid solution, until pH value is 1, active white crystalline tungstic acid powder is obtained. It is found that the product can be quickly dissolved in phosphoric acid. When producing white tungstic acid powder, sodium tungstate concentration, nitric acid acidity and reaction time, temperature, adding speed of reagent will affect the activity of white tungstic acid powder, it will then affect reacting rate with phosphorus acid.