Separation of lactic acid from acetic acid using a four-zone SMB.
A simulated moving bed (SMB) process has been developed to separate l-(+)-lactic acid from acetic acid, a major impurity in the fermentation broth of Lactobacillus rhamnosus. Poly(4-vinylpyridine) resin (PVP) was selected as the adsorbent. Adsorption isotherms and mass transfer parameters of the organic acids were estimated from single-column frontal tests. Experimental results show that the Langmuir isotherms obtained from the frontal tests can be used in the design of an SMB process to achieve 99.9% purity and over 93% yield of lactic acid. The column profiles and effluent histories, however, deviate from rate model predictions based on the Langmuir isotherms. They agree more closely with the predictions based on a modified Langmuir isotherm for lactic acid. The standing wave design method for systems with modified Langmuir isotherms is developed in this study. Rate model simulations show that the process based on the modified design method can achieve high purity (>99.9%) and high yield (>99.9%). For this nonlinear system, accurate isotherm model and model parameters are needed in the design, and the zone flow rates must be closely monitored and controlled in order to ensure high purity and high yield in the SMB process.
Lee
Ho-Joon
HJ
School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
Xie
Yi
Y
Koo
Yoon-Mo
YM
Wang
Nien-Hwa Linda
NH
D019342:Acetic Acid / Q000737:chemistry* / Q000302:isolation & purification*; D002845:Chromatography / Q000379:methods*; D003198:Computer Simulation; D005240:Feasibility Studies; D019344:Lactic Acid / Q000737:chemistry* / Q000302:isolation & purification*; D007778:Lactobacillus / Q000378:metabolism*; D008956:Models, Chemical
D019344:Lactic Acid; D019342:Acetic Acid