Concentration of Lactic Acid by Electrodialysis

Experiments were carried out to concentrate lactic acid by means of electrodialysis. Under certain operating conditions, the process was hindered by an increase in the volume of the concentrated solution as a result of water permeation across the membranes due to electro-osmosis and the difference in osmotic pressures. A necessary operating condition for successful concentration of lactic acid was that the concentration difference between the concentrated and dilute solutions should not be too large. The highest concentration of lactic acid economically achieved by electrodialysis was 50 wt%. This upper limit was related to an acute increase in the electrical resistance of lactic acid solution. In successive operations, it was found possible to concentrate lactic acid solution from 7 to 50 wt% through 13 cycles of electrodialysis.