Miles Laboratories, Inc.

Imi Tami Institute for Research and Development Ltd.

Ruth Blumberg

Avraham Matitiahu Baniel

Klara Hajdu

John E Alter

Acids are recovered from their aqueous solution by an extraction process comprising a first extraction stage at which the aqueous solution is contacted with a water-immiscible extractant comprising a water-immiscible organic solvent and, dissolved therein, at least one secondary or tertiary amine in which the aggregate number of carbon atoms is at least 20; and a back-extraction stage in which the organic extract, separated from the original aqueous solution, is stripped with an aqueous liquid at a temperature which is higher by at least 20.degree. C. than the temperature of the first extraction stage. The stripped extractant can be recycled to the first extraction stage for making the process continuous, and if so recycled, is cooled on its way to the extraction stage. A preferred field of application is the recovery of organic acids produced by fermentation from the fermentation broth, e.g. citric acid.

Recovery of acids from aqueous solutions

Citric acid can be extracted from aqueous citric acid solutions by contacting such solutions with an N-substituted alkyl amide containing a total of at least twelve carbon atoms.

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Haifa, Israel

Ruth Blumberg