Effects of operation variables on the recovery of lactic acid in a batch distillation process with chemical reactions

Abstract

In this study, the feasibility of recovery of lactic acid by batch reactive distillation using cation exchange resin as a catalyst was investigated. For the recovery of lactic acid, two reactions, esterification and hydrolysis, are involved and hence, an apparatus with two distillation columns was developed and operated in a batch mode to ensure enough residence time in the reboiler and column. The effects of operation variables such as catalyst loading, reactant mole ratio, feed concentration, type of alcohols and partial condenser temperature on the yield were studied. In this study, the reaction products of the esterification (methyl lactate and water) were distilled to the hydrolysis part to be recovered into pure lactic acid. The yield of lactic acid increased as catalyst loading in the esterification part increased and reactant mole ratio and feed lactic acid concentration decreased. Methanol as a reactant gave higher yield than any other alcohols. The yield of recovered lactic acid was as high as 90%. The yield of lactic acid was closely related to the boiling temperature of the reaction mixture in the esterification part.