文摘
In this work, a novel process for lactic acid purification based on ion exchange is proposed. It consists of twostages: first, a strong cation resin was used to reduce the broth pH below the pKa of lactic acid (3.86) andremove the cations present in the solution; then lactic acid was separated from the other anions in the brothusing a weak anion exchanger. The ion exchangers selected were Lewatit S2568H and Lewatit S3428 (Bayer,Germany). The Lewatit S2568H resin retained the cations in the broth with an apparent capacity of 1.7 equiv/L, reducing the broth pH below 3.86. It was able to decrease the pH of the broth to as low as 1.5, generating4 bed volumes (BV) of acidified and partial demineralized broth. In the second step, the acidified broth waspurified by the Lewatit S3428 resin, which retained the other anions present in the broth, producing an aqueoussolution of lactic acid. This resin was able to produce 25 BV of purified lactic acid with selectivity higherthan 99.9%. The final purity of lactic acid was higher than 99%.
