Liquid-Liquid Equilibria of Butyric Acid, Water, and Methyl Isobutyl Ketone with the Aid of Biological Buffer as a Green Auxiliary Agent

Biological buffer has a significant impact on aqueous organic phaseequilibria in extraction processes. This study investigated the effectof biological buffer on the efficacy of butyric acid extraction fromaqueous solution utilizing methyl isobutyl ketone (MIBK) as the extractionsolvent. The liquid-liquid equilibria (LLE) of quaternary systemsof methyl isobutyl ketone (MIBK) + butyric acid + water + biologicalbuffer MOPS [3-(N)-morpholino propane sulfonic acid],HEPES (2-(4-(2-hydroxyethyl)-1-piperazinyl)ethanesulfonic acid), orEPPS (4-(2-hydroxyethyl)-1-piperazine propanesulfonic acid) were determinedat temperature T = 303.15 K (30 & DEG;C) and P = 0.1 MPa (atmospheric pressure). The addition of EPPSto the butyric acid aqueous solution resulted in superior extractionefficacy compared to the other biological buffers, as determined byexperimental data. Generally, the extraction performance was in theorder EPPS > MOPS > HEPES, which represented the buffering-out strengthas well. The non-random two-liquid (NRTL) and UNIversal QUAsi Chemical(UNIQUAC) models fit well with the actual LLE data of the quaternarysystems. The & sigma;-profile analysis was also evaluated in this study.Additionally, a potential process flow sheet using biological bufferand MIBK solvent was suggested for removing butyric acid from itsaqueous solution.