Continuous extraction of penicillin G by emulsion liquid membranes with optimal surfactant compositions

In order to find optimal surfactant compositions of a membrane phase for vo lume ratios of internal aqueous phase to membrane phase (w/o ratios) suitab le for continuous extraction of penicillin G, batch extraction by an emulsi on liquid membrane (ELM) was studied by varying the volume percentages of S pan 80 in a binary surfactant mixture in the membrane phase. The optimal vo lume percent of Span 80 for each w/o ratio was 5 or 10% (v/v) of total volu me of the binary surfactant mixture. The continuous extraction was investig ated using a column of the Oldshue-Rushton type. Total flow rate, w/o ratio and flow rate of a dispersed emulsion phase were considered as the operati onal variables for the continuous extraction. In most of the runs, actual d egrees of extraction at the bottom of the column were higher than 95%. Howe ver, the highest concentration of penicillin G in the internal phase of the emulsion effluent from the column was about 2.4 times higher than that in the influent continuous phase. The low concentration of penicillin G result ed from dilution of the internal phase due to swelling of the emulsion phas e. In addition, strategies for reduction of the swelling were investigated. (C) 2000 Elsevier Science S.A. All rights reserved.