ELECTROTRANSPORT OF ALANINE THROUGH ION-EXCHANGE MEMBRANES

The extraction of alanine by electrodialysis was studied taking into consideration the competition of protons or hydroxyl ions in the membrane transport process. The diffusion and electrodiffusion of alanine from solutions (1M) were examined at different pH varying from 1.4 to 11, by measuring, under different current densities in the range 0-30 mA-cm-2, the alanine fluxes through an anion exchange membrane as well through a cation exchange membrane. The best value of the acid pH for extraction of alanine into the cationic form is around 2.1. At lower pH the competition of protons is too strong. For extraction of alanine into the anionic form the best value of the basic pH is 11 where the current efficiency is near 100%. In the electrotransport of alanine, concentration polarization and water splitting in the anion exchange membrane have an influence on the alanine extraction rate.