ANTIOXIDIZING METHOD OF IRON AND THE LIKE IN SOLUTION OF ALKALI ALUMINATE IN AQUEOUS CAUSTIC ALKALI SOLUTION

摘要

PURPOSE:To prevent the oxidation of iron in a solution of an alkali aluminate in an aqueous caustic alkali solution and further the coloring of a product prepared by utilizing the same, by adding a specific chelating agent to the solution of the alkali aluminate in the aqueous caustic alkali solution. CONSTITUTION:Any one of gluconic acid or an alkali salt thereof, tartaric acid or an alkali salt thereof, triethanolamine or sorbitol as a chelating agent is added to a solution of an alkali aluminate in an aqueous caustic alkali solution. The amount of the chelating agent is preferably 0.1-10g/l for the gluconic acid or the alkali salt thereof, 0.1-10g/l for the tartaric acid or the alkali salt thereof, 1.0-10g/l for the triethanolamine and 1.0-10g/l for the sorbitol. If the amount is less than the above-mentioned lower limit, the effect of the addition is not produced. If the amount is higher than the above-mentioned upper limit, the effect is not changed and uneconomical.