Simulation of Extraction Process in Dual-Flow Countercurrent Extraction

In the extractive purification of commercial glycyrrhizin (about 90% in purity) with dual-flow countercurrent extraction, the extractive recovery of an impurity in the sample was wrongly estimated by a reported calculation method. To investigate the cause, we simulated the extractive separation of the impurity from glycyrrhizin by dual-flow countercurrent extraction. If one used the reported calculation method, the extraction recoveries of the impurity into the organic phase were calculated as 40.6% or as 99.3%, on two different assumptions: (1) the distribution ratio of the impurity changed depending on its concentration, or (2) it varied with the concentration of glycyrrhizin in the extraction apparatus. The experimental results (99.1% recovery of the impurity in the organic phase) agreed with the calculation based on the latter assumption. With the calculation method, the distribution map of the components in the extraction column could be shown as well.