Computational study of the acetic acid extraction process from an aqueous solution with the aid of biological buffer

The liquid-liquid extraction of acetic acid from an aqueous solution with 1-heptanol as an extraction solvent in the extraction column and mixer-decanter at 30°C and atmospheric pressure was simulated using Aspen Plus. A Non-Random Two-Liquid (NRTL) based model was developed by minimizing maximum-likelihood objective function. In the simulation of the extraction column and mixer-decanter, the effect of the number of stages and the flow rate of the solvent on the percent recovery can be seen. In addition, a comparison of the percent recovery value between acetic acid extraction systems using EPPS (4-(2-hydroxyehtyl)-1-piperazine propanesulfonic acid) and HEPES (4-(2-hydroxyethyl)-1 piperazineethanesulfonic acid) buffers was also carried out with systems without buffers. In this study, an economic analysis was also carried out for the acetic acid extraction system using an extraction column and a mixer-decanter. Based on the simulation results, the acetic acid extraction system with the addition of HEPES buffer using extraction column with the number of stages = 8 and solvent to feed mass ratio = 1.6 was the most optimal and efficient extraction process obtained in this study. This system has the capital cost of 180,729,262.67 USD with the percent recovery up to 99.83% and the mass fraction of acetic acid in the raffinate phase is 0.0002 which is also extremely low.