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 volume ratios of internal aqueous phase to membrane phase (w/o ratios) suitable for continuous extraction of penicillin G, batch extraction by an emulsion liquid membrane (ELM) was studied by varying the volume percentages of Span 80 in a binary surfactant mixture in the membrane phase. The optimal volume percent of Span 80 for each w/o ratio was 5 or 10% (v/v) of total volume of the binary surfactant mixture. The continuous extraction was investigated 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 operational variables for the continuous extraction. In most of the runs, actual degrees of extraction at the bottom of the column were higher than 95%. However, 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 resulted from dilution of the internal phase due to swelling of the emulsion phase. In addition, strategies for reduction of the swelling were investigated. (C) 2000 Elsevier Science S.A. All rights reserved.