Abstract
A process for production of purified lactic acid from fermentation-derived magnesium lactate is conceptually designed and simulated using Aspen Plus simulator equipped with RADFRAC module. The process employs two reactive distillation columns: one, the RD column, for esterification of acidified magnesium lactate solution, and the other, the HY column, for hydrolysis of the produced ethyl lactate back to lactic acid. Series of fractional distillation columns are used in order to increase purity of the final product. The process design is a 2000-fold scale up based on experimental results obtained from a laboratory scale fermenter producing 50 L of the fermentation broth containing magnesium lactate resulted from neutralization of lactic acid by magnesium oxide. Key operating variables, such as total number of stage, distillate rate, reflux ratio and feed location, are optimized in order to maximize the production yield. Under the optimal conditions, conversion of lactic acid in the RD column is found to be 97.25 %, while the recovery of the produced ethyl lactate before it is subjected to hydrolysis is 99.86 %. The final product is received as an aqueous solution with the acid concentration of 59.52 mol% or 88.01 w/w%. The acid production rate is found to be 4.11 kmol/h or 370.39 kg/h with the energy consumption of 31.11 kJ/kg of lactic acid produced.
