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US 4,820,501 AGranted
Method for removing organic materials dissolved in purified phosphoric acid
AssigneeTosoh Corporation
InventorMasaki Nakatani
Life of this patent
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Abstract
A method for removing organic materials dissolved in purified phosphoric acid by decomposing it with hydrogen peroxide, characterized in that after the treatment with hydrogen peroxide, the purified phosphoric acid is contacted with reducing phosphorus compounds.
Claims8
A method for removing organic materials dissolved in phosphoric acid, which comprises the steps of:
- (i) decomposing said organic materials with hydrogen peroxide to obtain a purified phosphoric acid which contains residual hydrogen peroxide;
- and
- (ii) contacting said purified phosphoric acid with a reducing phosphorus compound which is at least one member selected from the group consisting of elemental phosphorus, phosphorus hydrides, and lower oxyacids of phosphorus, such that the amount of said reducing phosphorus compound is at least stoichiometric to said residual hydrogen peroxide and at a temperature of at least 80.degree. C. to obtain a further purified phosphoric acid.
Dependencies are inferred from the claim text.