Experimental and theoretical study on liquid-liquid equilibrium of 1-butanol+water+NaNO3 at 25 and 35°C

In this work liquid-liquid equilibria (LLE) in the system containing 1-butanol-water-sodium nitrate at temperatures of 25 and 35°C has been investigated experimentally and theoretically. The extended UNIQUAC model has previously been used for correlation of liquid-liquid equilibrium in aqueous salt systems containing alcohols. In that model the excess Gibbs energy consists of two terms, the original UNIQUAC term and Debye-Hückel term which considers the alcohol as a non-electrolyte solute. In this work, a modified extended UNIQUAC model is used by taking into account mixed solvent theories. The model consists of three terms, the original UNIQUAC term, a Pitzer-Debye-Hückel term and a Born term. The model has been found to give a satisfactory description of LLE data obtained in this work, with an average absolute deviation of less than 0.5 in calculated mass percent compared to experimental data

Salt influence on MIBK/water liquid–liquid equilibrium: Measuring and modeling with ePC-SAFT and COSMO-RS

In biotechnological processes, salts might be present during reaction steps and in downstream processes. Salts are known to have a strong impact on phase equilibria of aqueous systems.In this work, the liquid-liquid equilibria (LLE) of ternary salt/MIBK/water mixtures were measured at 298.15 K and 1 bar up to the salt solubility limit. The salts studied in this work were NaCl, LiCl, KCl, NaNO3, LiNO3, Na2SO4, CH3COONa, and CH3COOLi. From these LLE measurements it was found that a high amount of salt is dissolved in the aqueous phase whereas only a very small amount of salt was detected in the MIBK phase. Further, the salting-out behavior of MIBK from the aqueous phase upon addition of different salts was investigated to study ion-specific effects.Two ion-specific models, ePC-SAFT and an extended version of COSMO-RS for electrolytes were used for modeling the binary system MIBK/water and ternary salt/MIBK/water systems. In case of the COSMO-RS based approach, the modeling results were fully predictive. In contrast, ion-specific binary interaction parameters between MIBK and ions were fitted to experimental LLE data of the ternary systems salt/MIBK/water when using ePC-SAFT. The results show that the COSMO-RS based approach allows for predicting the salt influence on LLE with acceptable accuracy, whereas ePC-SAFT allows for almost quantitative correlations of experimental data