Mass transfer studies of amino acids and dipeptides in AOT–oleyl alcohol solution using a hollow fiber module

Abstract

Abstract The mass transfer of amino acids [tryptophan (Trp), phenylalanine (Phe) and dipeptides (tryptophan–leucine (Trp–Leu), phenylalanine–leucine (Phe–Leu)] was studied by using a hollow fiber module (HFM). The membrane module (2.5 cm diameter×20 cm long) has a shell-and-tube configuration and allows flow of two streams in the fiber and shell sides. The liquid membrane contained an ionic carrier, Aerosol OT (AOT), dissolved in oleyl alcohol. The module was operated by both the membrane extraction and supported liquid membrane (SLM) mode. In the SLM mode, the organic solution was loaded inside the micropores and a ‘feed’ solution (an aqueous solution containing the target solutes) and a ‘strip’ solution (containing sodium chloride) were circulated through the shell and fiber sides, respectively. The results were not encouraging so the experiments were performed in the membrane extraction mode. This was done by recirculating the feed and the organic solutions through the shell and fiber sides, respectively. The effects of recirculation flow rate, initial feed pH and concentration on the percentage extraction have been determined. The equilibrium reactions at the interfaces and mass transfer from the fiber side to the shell side were analyzed with a simple theoretical model. The distribution coefficient was obtained from two-phase partition experiments and used to calculate the overall mass transfer coefficient.