Recovery of acids from aqueous solutions
Patent 4275234 Issued on June 23, 1981. Estimated Expiration Date: 
June 23, 1998. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
June 23, 1998. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2880179 Process of producing alkali metal or ammonium citrates Patent #: 3944606 InventorsAssigneeApplicationNo. 05/365506 filed on 05/31/1973US Classes:562/584, Citric acid per se or salt thereof562/580Purification or recovery per seExaminersPrimary: Killos, Paul J.Attorney, Agent or FirmInternational ClassesC07C 51/42 (20060101)C07C 51/48 (20060101) Foreign Application Priority Data1972-06-19 ILAbstractAcids 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° 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.Other References
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