PHARMACEUTICAL PRODUCT RECOVERY USING A HOLLOW FIBER CONTAINED LIQUID MEMBRANE - A CASE-STUDY

Recovery of diltiazem as diltiazem malate in a L-malic acid containing aqueous strip stream from an alkaline aqueous feed solution has been studied using a hollow fiber contained liquid membrane (HFCLM) separation-reaction device. The resistance to mass transfer is primarily controlled by the feed side mass transfer coefficient due to the high partition coefficient of diltiazem for a decyl alcohol liquid membrane and the instantaneous reaction in the strip side of the membrane. However, for larger thicknesses of the liquid membrane, the membrane resistance becomes quite important. In spite of the very low diltiazem concentration in the feed solution, high concentrations of diltiazem malate in the stripping solution were achieved by using a high L-malic acid concentration and recirculation of the strip solution from a batch reservoir. A first order model describes effectively the observed behavior of the HFCLM separation-reaction device. A preliminary cost analysis and comparison with packed bed solvent extraction shows the technique to be highly competitive.