SEPARATION AND CONCENTRATION OF PHENYLALANINE BY EMULSION LIQUID MEMBRANE IN A CSTR EXTRACTION PROCESS

The extraction and concentration of phenylalanine by the continuous CS TR emulsion liquid membrane (ELM) separation process has been evaluate d. We discussed the influence of operating conditions on the separatio n and concentration efficiencies of phenylalanine. It was found that t he extraction rate of phenyl-alanine increased as the amount of emulsi on used and the internal concentration of H+ increased. However, the c oncentration ratio of phenylalanine increased as the emulsion amount a nd acid concentration increased only up to a certain limit and then de clined with further increases of these. The reduction of the concentra tion ratio is due to the swelling of the emulsion drops. Two effects, swelling owing to osmotic pressure and swelling caused by the entrainm ent of water due to mechanical agitation, are responsible for the swel ling of emulsion drops. A mass transfer model for analyzing the extrac tion of phenylalanine by liquid surfactant membrane is presented. The model assumes that the extraction and stripping reactions are reversib le, and that the reaction equilibrium exists in both the internal and the external interfaces. The scheme for mass transfer is based on a ho llow sphere model. The phenomena of osmotic swelling, mechanical entra inment, and breakage are all considered in the mathematical treatment. The effects of operation parameters on the extraction efficiency and concentration ratio are discussed by simulation.