Aqueous Two-Phase Systems: A Correlation Analysis

Abstract

Aqueous two-phase systems involve a limited region of a complicated phase diagram usually containing solid phases. Studies regarding these systems generally focus on the liquid-liquid region because it provides a suitable medium for liquid extraction of biomolecules and metal ions. In this work, the whole phase diagram was determined for ternary mixtures of water, dipotassium tartrate and ethanol or propanol at several temperatures and atmospheric pressure. In addition, density and refractive index of a diluted region of the mixtures were measured for compositional analysis of samples. Different regions were found involving solid and liquid phases, or the anhydrous and hemi-hydrated salt. The correlation of equilibrium data within the different regions was carried out with the NRTL model. To that aim, some restrictions were required to ensure the miscibility of the binary subsystem with water and alcohol. Individual correlation at each temperature and simultaneous correlation of data at all temperatures led to adequate phase diagram representation and low deviations. In spite of the use of temperature dependent parameters, results were slightly worse in the latter case (around or below 1%). The LLE data alone were also correlated, obtaining similar deviations to those obtained considering all equilibrium data. In all cases deviations found with propanol are higher (in the range of 3-4%) due to the proximity of the LLE region to the miscible water + propanol binary subsystem. The correlation of exclusively LLE data is

A High-Performance Guanidinium-Based Aqueous Biphasic System for Green Separation of Palladium from Acid Solution

“…Therefore, as evident in Figure , the phase-forming ability of TMGH is better than that of TMGV. This is due to the increase in the van der Waals interaction caused by the longer alkyl chain and the lower surface tension of the system, which leads to more water molecules in the system that bind to inorganic salts and promote the formation of two phases. In addition, the hydration capacity of the IL is also one of the factors affecting phase formation.…”

Outstanding Performance of the Deep Eutectic Solvent-Based Aqueous Biphasic System Constructed with Sodium Citrate for a Green Gold Separation

“…The binodal curve of each DES-based ABS was determined using the cloud point titration method . At 298.15 ± 1 K, a certain amount of DES was accurately weighed on a scale and added to a tube, and then a few drops of deionized water were added.…”

Revising Concepts on Liquid–Liquid Extraction: Data Treatment and Data Reliability

“…Important errors may arise when incomplete or limited data sets are used in the data correlation . This problem is of particular relevance in aqueous two-phase systems since in most cases a very limited set of tie-lines are provided, and the extension of the LLE region is studied in very few cases. , …”

“…Even so, that is scarcely found in the literature. Moreover, the complete phase diagram, including solid phases when present, are even scarcer to find in the literature. , Considering all the above, it seems that providing the LLE data should cover the whole LLE region, starting from the binary subsystems (tie lines in the axes of the triangular diagram). Indeed, as for modeling purposes, the availability of LLE data for the binary systems (temperature–composition data) would be very useful for any ternary LLE data treatment.…”