Liquid–Liquid equilibria for trioctylamine/1-dodecanol/lactic acid/water system at 306.1, 310.1 and 316.1 K: Experimental Data and Prediction

Abstract

Liquid–liquid equilibria of aqueous solutions of lactic acid with trioctylamine diluted in 1-dodecanol was measured experimentally at three temperatures (306.1, 310.1, and 316.1 ± 0.1 K). During the transfer process, lactic acid reacts with trioctylamine to produce an amine–lactate complex. Two models were proposed to predict the liquid–liquid equilibria. The first model considered the equilibrium constant of chemical reaction and the distribution coefficient. Those parameters have been determined by fitting the experimental data. The distribution coefficients have also been experimentally measured. It was found that as temperature increases, the distribution coefficient increases and equilibrium constant decreases. The second proposed model involved the non-random two liquid activity model. Energies of binary interaction and the equilibrium constant of chemical reaction were fitted to experimental data. The equilibrium constant and partition coefficients show the same trends as the first model; however, the first model shows a better prediction as compared to the second model of the liquid–liquid equilibrium data. These two models are especially suitable at low lactic acid concentrations in the aqueous phase where the experimental standard deviation is low.