THE MODELING OF CARBON DIOXIDE-AIDED EXTRACTION OF CARBOXYLIC-ACIDS FROM AQUEOUS-SOLUTIONS

Carbon dioxide (CO2)-aided acidification of aqueous carboxylate soluti ons and simultaneous reactive extraction of the carboxylic acid is a p romising and clean alternative method for the conventional recovery of carboxylic acids. The complexity of the extraction system is endorsed by the presence of three or four coexisting phases (i.e., vapor-liqui d-liquid-(solid)) and an aqueous electrolyte solution. Selection of op timal operating conditions in this complex four-phase system requires a robust, yet simple model for description of the phase equilibria. th is work, such a simple shortcut model is presented. Although the model parameters are obtained from pure component or infinite dilution data only, the model yields a reasonable description with experimental dat a. Model predictions were compared with experimental data for the CO2- aided extraction of lactic acid with two different amine extractants f rom various concentrations of a calcium lactate solution and pressures up to 3.1 MPa. The model is expected to be very useful for equipment and process design.