Separation of D, L-Lactic Acid by Filtration Process

摘要

The purpose of this research was to study the optimum conditions for separation of D,L-lactic acid isomer by filtration process using polytetrafluoroethelene (PTFE) membrane filter. The study on suitable chiral selector by adding chiral selector into D,L-lactic acid and separate through membrane filter showed that the separation time of 30 min by using 2.67 g/l (v/v) β-cyclodextrin as chiral selector was the most suitable for separation of D,L-lactic acid isomer. Efficiency of carrier on separation of D,L-lactic acid isomer was studied. D,L-lactic acid was separated through the carrier impregnated membrane filter, the results showed that modified Aliquat~(TM)336 in carbonate form was the most efficient for separation of D,L-lactic acid isomer. In addition, efficiency improvement of D,L-lactic acid isomer separation was carried out by using p-cyclodextrin as chiral selector, the impregnated membrane filter with modified Aliquat~(TM)336 and 2 stages of separation by filtration process that separation time of 30 min each step. It was found that the first separation stage could be separate D-lactic acid Irom L-lactic acid in transmembrane solution, the D,L-lactic acid separation factor achieved was 2.93. High efficiency of D,L-lactic acid isomer separation was obtained from the second stage and separation factor was as high as 4.43 in this stage.