Separation of penicillin G by reactive extraction and emulsion liquid membrane

Abstract

Reactive extraction of penicillin G at pH 5 and re-extraction at pH 7 - 8 were performed using Amberlite LA-2(carrier: secondary amine) in n-butyl acetate. The volume ratios effects of aqueous feed phase to organic extract phase in extraction and organic extract phase to aqueous strip phase in re-extraction on the degree of extraction and enrichment were studied. The effects of initial concentration ratio of carrier to penicillin G on the degree of extraction and enrichment were also investigated. It was found an optimum carrier concentration giving the maximum degree of extraction and enrichment. Procedure for the selection of volume ratios and concentration ratio was studied for initial penicillin G concentration of $10mmolㆍdm^{-3}$. It could be generalized to be applicable for any concentrations of penicillin G. In addition, sodium carbonate solution was successfully applied as an aqueous strip phase on behalf of buffer solution in re-extraction to avoid the dis-advantages of using buffer solution and to shorten the re-extraction time. To confirm the applicability of the extraction of penicillin G by an emulsion liquid membrane(ELM), the degree of decomposition of penicillin G during extraction was theoretically calculated. Results showed that the degree of decomposition was less than 1% provided that the initial concentration of sodium carbonate solution in the internal phase was properly determined. The procedure to determine the initial concentration of sodium carbonate solution in the internal phase was also proposed in order that the pH in the internal aqueous phase should be within the relatively stable range for the penicillin G at the end of the extraction. Extraction of penicillin G by an emulsion liquid membrane was also performed. The effects of surfactants, diluents, and carriers mixture and their combination upon the initial extraction rate and the emulsion stability were investigated. Surfactants, diluents, and carriers used were Span80(Sorbi...