STUDIES ON EMULSION LIQUID MEMBRANE EXTRACTION OF CEPHALEXIN

An experimental study on batch extraction of cephalexin using an emuls ion liquid membrane system has been reported. The effects of surfactan t, carrier and solute concentrations, phase volume ratio, stirring spe ed, and counterion concentration on the extraction rate were examined. Surfactant, carrier and diluent used were Span-80, Aliquat-336 and n- heptane-kerosene (1:1), respectively. Under the optimised experimental conditions, emulsion swelling was found to be marginal. By maintainin g an appropriate pH gradient in the feed and receiving aqueous phase, facilitated transport could be realised. Selective separation of cepha lexin from a mixture of 7-aminodeacetoxy cephalosporanic acid (7-ADCA) could be demonstrated in the emulsion Liquid membrane system. A mathe matical model based on mass transfer across aqueous boundary layer, in terfacial chemical reaction and diffusion in the emulsion globule prov ides a reasonable fit of the experimental solute concentration versus time profiles in the emulsion liquid membrane system. (C) 1998 Elsevie r Science B.V.