| 摘要 |
PURPOSE:To obtain high-purity concd. sulfuric acid from spent sulfuric acid at the time of separating salts from the sulfuric acid contg. the salts by diffusion dialysis method by using an anion-exchange membrane having a specified diffu sion constant as the diaphragm. CONSTITUTION:A sulfuric acid soln. is separated from spent sulfuric acid contg. metallic salts, etc., by diffusion dialysis method using an anion-exchange membrane with the diffusion constant of salts controlled to <=4/1000 of that of sulfuric acid as the diaphragm. The water in the sulfuric acid soln. is vaporized, and SO3 is absorbed to concentrate the soln. to >=1400g/l concn. High-purity concd. sulfuric acid capable of being used in the production and refining of TiO2 is easily recovered by this method. When the diffusion constant of salts is controlled to >4/1000, scales of iron sulfate, etc., are generated in the vaporization of water or in the absorption of SO3, and high-purity concd. sulfuric acid is not obtained. |
