Recovery and Purification of Amino Acid by Electrodialysis

Abstract

The improvement in permeability of glutamic acid across anion ion exchange membrane was investigated. The permeability of glutamic anion across the anion exchange membrane depends greatly on the temperature and concentration of glutamate in the solution and it is highest at the 2mol/l of glutamate under the condition of the temperature over 40°C obtained from the measurement of limiting current density.
The perm-selectivity coefficient (T^A_B) of various ions contained in the glutamate fermentation broth was calculated on the basis of the glutamic acid from the data of electrodialysis operated by the following conditions; current density 2A/dm², concentration of glutamate 1.67mol/l pH 6.5, circulation rate 1.3cm/s. The order of relative selectivity was as follows; K>Na>Mg>Ca>color substance>Protein. More than 80% of the neutral amino acids remained in the feed solution through the electrodialysis operation.
The effect of the temperature on the relative perm-selectivity coefficient of glutamate ion to sodium ion was measured and found to be 0.05 for 15°C and 0.54 for 55°C.
The two stage operation of electrodialysis for recovery and purification of glutamate from fermentation was performed; first stage operated for demineralization at 15del.°C charged with 5.2 V for about 14 hours and the following stage operated for removal of weak or non electrolyte substances at 55°C charged constant current density of 2A/dm² for 12 hours. The recovery of glutamate was 95% and more than 95% of salts were removed and colored substance was also removed about 80%. For the application of ion exchange membrane to glutamate industry, further innovation of membrane and the development of design technology of the process are necessary.