EXTRACTION OF CITRIC ACID BY LIQUID MEMBRANE EXTRACTION.

Citric acid has been successfully extracted and concentrated from aqueous solutions and fermentation broths using the liquid membrane process. Results are reported for 10% (w/v) citric solutions, for which almost complete extraction was achieved in about 6 minutes, in a stirred vessel. Under these experimental conditions the overall kinetics are approximated by a pseudo first-order relation. For the emulsions to be functionally stable it is necessary to select suitable combinations of surfactants and internal stripping agents. Alamine 336 diluted in various solvents was used as a complexing agent for citric acid from aqueous solution, and sodium carbonate solutions were used as the internal stripping agent. For this system a non-ionic surfactant, Span 80, was used.