1. Process for the extraction of organic acids from aqueous solution. European Patent EP 0 049 429 (1982).
2. and , Process for recovering a carboxylic acid. US Patent 4323702 (1982).
3. and , Separation of lactic acid from fermentation broth with an anionic polymeric absorbent. US Patent 5068418 (1991).
4. and , Sorption of carboxylic acid from carboxylic salt solutions at pHs close to or above the pKa of the acid, with regeneration with an aqueous solution of ammonia or low-molecular-weight alkylamine. US Patent 5132456 (1992).
5. Recovery of l-(+)-lactic acid by anion exchange resin Amberlite IRA-400