PURPOSE: To perform the above-mentioned separation economically and efficiently, by making the water-soluble organic acid migrate selectively by contacting the mixed aqueous solution of inorganic acid and water-soluble organic acid with the solution of water-soluble carboxylic acid in an inert solvent and by making the water-soluble organic acid migrate into water by contacting the extracting liquid with water.
CONSTITUTION: As the water-insoluble carboxylic acid, the carboxylic acids above C8, for example, 2-ethylhexanoic acid, caprylic acid, etc., are used. As the inert solvent, the stable hydrocarbon solvents having boiling point above almost 100°C and insoluble in water, for example, kerosene, etc., are used. Generally, by contacting the mixed aqueous solution of at least one kind of inorganic acids and at least one kind of water-soluble organic acids to the solution containing 0.5W5mol of the water-ins oluble carboxylic acid per 1l of the inert solvent, the water-soluble organic acid is made to migrate into the solution of inert solvent. Then, by contacting the extracting liquid with water, the water-soluble organic acid is extracted reversely into water. Because the mixed waste liquid can be treated continuously, this separating method is efficient and the recovered organic acid is comparatively pure and is reused economically.
MORI TAKESHI
TOIDA SHIYOUICHI
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