PURPOSE: A sulfuric acid solution is purified by precipitating and removing iron ions or copper ions existing in a sulfuric acid solution containing soluble organic materials reactive to hydrogen peroxide especially in an acidic range and promoting the decomposition of hydrogen peroxide.
CONSTITUTION: Hydrogen ferrocyanide or hydrogen ferricyanide or their salts (e.g. potassium ferroxyanide, ammonium ferricyanide, etc.) are added to a sulfuric acid solution containing soluble organic materials containing iron ions and/ or copper ions, and the mixture is heated at ≤60°C to precipitate and remove the iron ions and/or copper ions. The amount of the hydrogen ferrocyanide, ferricyanide or their salt is dependent upon the amount of the iron ion or copper ion dissolved in the sufluric acid solution, and is determined based on the stoichiometric amount. Since the sulfuric acid solution usually contains a large amount of iron ion and little copper ion, the amount of the hydrogen ferrocyanide, etc. is determined based on the amount of iron ion.
YADA TOMINORI
HOTTA TOSHIAKI
MAYAMA NORIKAZU
EIWA CHEM IND
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