ADDITIVE FOR RESTORATION OF CHROMIUM (IV) IONS IN CHROMIUM (III), METHOD FOR ITS PRODUCTION AND APPLICATION OF THE ADDITIVE

摘要

1. An additive for the reduction of Cr (VI) ions in Cr (III) containing an aqueous solution of a complex of tin (II) and a carboxylic acid or one of its salts. ! 2. The additive according to claim 1, which is a clear aqueous solution. ! 3. The additive according to claim 1, in which the carboxylic acid is gluconic acid. ! 4. The additive according to one of claims 1 to 3, which additionally contains an agent that corrects the pH. ! 5. The additive according to claim 4, in which the pH adjusting agent is selected from alkanolamines. ! 6. The additive according to claim 4, in which the pH adjustment agent is sodium hydroxide. ! 7. The additive according to one of claims 1 to 3, which further comprises an antioxidant selected from the group consisting of hydroquinone and its derivatives, propyl gallate, 2 (3) t-butyl-4-hydroxyanisole, 2,6-di tert-butyl-p-cresol, ethyl vanillin, rosemary oil, lecithin or vitamin E.! 8. A method of producing an additive as claimed in claims 1 to 7, characterized in that the tin (II) salt is contacted with a carboxylic acid or with one of its salts in the presence of an appropriate amount of water. ! 9. The method according to claim 8, characterized in that the molar ratio of carboxylic acid to the tin (II) compound is from 0.5: 1 to 5: 1. ! 10. The method according to claim 8 or 9, characterized in that the tin (II) compound is selected from the group consisting of tin (II) chloride, tin sulfate, tin fluoride and tin acetate. ! 11. A method of obtaining a material with a low content of chromium (VI), characterized in that the material is brought into contact with an appropriate amount of the additive claimed in claims 1-7. ! 12. The method according to claim 11, characterized in that the material is a hydraulic binder. ! 13. The method according to p. 12, characterized in that the material is selected from the group consisting of