Recovery process of lactic acid using two distillation columns

Abstract

Lactic acid is of interest as the raw materials of polylactide that is a biodegradable polymer. For an effective purification of lactic acid, batch distillation with the simultaneous reactions was used. Two Oldershaw columns and reboilers were used for fractionation of methanol and reactions. Esterification reaction of lactic acid with methanol produced methyl lactate and water. The products of the esterification reaction, methyl lactate and water were transported to the reboiler of the hydrolysis part. In hydrolysis part, reaction of methyl lactate and water reproduced lactic acid and methanol. Methanol produced in the hydrolysis part and unreacted methanol in the esterification part were separated by distillation and recycled to the reboiler of the esterification part so that the esterification reaction would be stimulated. Thus, pure lactic acid solution remained in the reboiler of the hydrolysis part. The effect of the number of stages in column on the recovery yield was also investigated. In the operation with columns the recovery yield of lactic acid was improved. It is due to the fact that the columns improved the fractionation of components and stimulated the reactions in two parts.