Membrane-based extraction of cholesterol lowering drug: Effect of membrane type on extraction

Compactin (ML-236B) is an effective ingredient for production of anti-hypolipidemia medicine called mevalotin (Sankyo Pharmaceutical Co. Ltd.). Conventional liquid-liquid extraction is now applied in the commercial process of purification and concentration of compactin. In this study, we investigated compactin extraction process from aqueous solution to organic solvent of ethyl acetate using a microporous membrane-based flat interface contactor. Teflon (polytetrafluoroethelene; PTFE) membranes with 0.1 μm pore size with either hydrophilic or lipophilic surface were utilized under the study. The extraction experiments were conducted at 298 K. The main objective of this study was to investigate mass transfer characteristics of compactin extraction by different types of membranes at the same operating conditions. Our previous work showed that water and ethyl acetate transferred simultaneously with compactin during the extraction. Therefore, the study of mass transfer in a binary mixture of two solvents was indispensable. Local mass transfer coefficients of extraction could be estimated from the mass transfer of binary mixture, and mass transfer models for membrane extraction were developed. These mass transfer coefficients and models can be applied to any operating conditions. We found that extraction of compactin by lipophilic membrane has better performance than the extraction with hydrophilic membrane due to the faster transfer of ethyl acetate relative to water.