Abstract:  Over the traditional fixed bed ion exchange, continuous ion exchange has several significant advantages for the separation of L-lactic acid, such as continuous, stable and efficient. Economic, continuous and efficient separation of L-lactic acid was achieved using a continuous ion exchange process designed based on the results of static adsorption and fixed-bed ion exchange. Through static adsorption experiments, 732 type resin was identified as the best resin, which could reach adsorption equilibrium within 1 min with a maximum adsorption quantity of 345.97 mg/g. The best desportion agent was 0.5 mol/L H2SO4. In fixed bed ion exchange experiments, a desorption rate of over 97% was obtained under the conditions: sample loading flow rate 40 mL/min, column height-to-diameter ratio 7.5:1, breakthrough time 21.5 min, and desportion with 0.5 mol/L H2SO4. In continuous ion exchange experiments, the optimal sample loading flow rate at the exchange areas (1#－6#), washing areas after exchange (18#－20#), regeneration areas (12#－17#), washing areas after regeneration (9#－11#), top water areas with product (7#－8#) were 40, 40, 140, 35 mL/min and 20 mL/min, respectively. Each outlet concentration showed a cyclical change.

Key words: L-lactic ammonium, L-lactic acid, separation, static adsorption, fixed bed, continuous ion exchange