Phase behavior of aqueous two-phase systems composed of 1-ethyl-3-methylimidazolium tetrafluoroborate and phosphate-based salts at different temperatures

The binodal data for an aqueous two-phase system (ATPS) containing 1-alkyl-3-methylimidazolium tetrafluoroborate ([C n mim]BF4, n = 2, 3, 4) or 1-alkyl-3-methylimidazolium chloride ([C n mim]Cl], n = 2, 4, 6, 8, 10, 12) and inorganic salts (K2HPO4, NaH2PO4, (NH4)2SO4, and NaCl) or organic salts (sodium citrate, sodium tartrate, and sodium acetate) were widely determined at T = 298.15 K. The various binodal curves could be fitted and summarized as two kinds of empirical nonlinear equations with the lowest standard deviation (SD). The effects of the salt type and cation alkyl chain length of the ionic liquid (IL) on ATPS binodal curves were further discussed. It was displayed that the salting-out ability of different salts was a major factor in these ATPS formations. For [C n mim]BF4-based ATPS, the salting-out ability of various salts decreased in the following order: (NH4)2SO4 > Na3C6H5O7 > Na2C4H4O6 > NaH2PO4 > NaC2H3O2 > NaCl. For the [C n mim]Cl aqueous solution, only K2HPO4 or (NH4)2SO4 could cause the phase separation and formed ATPS, and the salting-out ability of K2HPO4 was stronger than the effect of (NH4)2SO4. The phase separation abilities of the researched [C n mim]BF4 in the corresponding ATPS increased with the increase of cation alkyl chain length, while [C8mim]Cl had the best phase separation ability of the researched [C n mim]Cl-based ATPS.

Section: Resultsmentioning

confidence: 70%

Effect of Salt Type and Alkyl Chain Length on the Binodal Curve of an Aqueous Two-Phase System Composed of Imidazolium Ionic Liquids

Liu

Zhao

et al. 2018

“…In this session, correlations of the 17 ternary aqueous systems of IL–salt through LLE calculation were carried out. ,,− Table shows the specification of the ATPSs, which were investigated, in terms of the temperature range and number of tie-lines for each system. Moreover as shown in this table, the maximum weight percent values of the IL and salt of the binodal curves were given for the ternary ATPS.…”

Section: Resultsmentioning

confidence: 99%

Correlation of Ternary Aqueous Two-Phase Systems Containing Ionic Liquids and Salts Using Symmetric Electrolyte Local Composition Models: NRTL-NRF, UNIQUAC-NRF, and UNIQUAC

Tehrani

Haghtalab

2019

The aqueous two-phase systems (ATPSs) are widely used for the extraction of biomolecules such as proteins and pharmaceuticals using polymer–salt and ionic liquid–salt systems. In this work, we correlated the experimental data of the 17 ATPSs containing ionic liquids and salts, comprised of 292 tie-lines. First, to obtain the interaction parameters of salt–water, the mean activity coefficients of the 11 binary aqueous electrolyte systems were regressed, and then, the liquid–liquid equilibrium calculations were performed to correlate the ATPSs. In the present work, three symmetrical local composition models such as NRTL-NRF, UNIQUAC-NRF, and UNIQUAC along with symmetric Pitzer–Debye–Hückel (PDH) theory were used. The local composition models and PDH theory were applied for the short-range and long-range interactions, respectively, by assuming complete dissociation of salts for the PDH term and ion-pair approach for the salts, water, and ionic liquids in the local composition models. The molecular volume and the structural parameters of the ionic liquids such as the surface area are obtained using the literature data; however, these parameters for 1-ethyl-2,3-dimethylimidazolium ethyl sulfate are calculated by Jmol software (an open-source Java viewer for chemical structures in three-dimensional). Furthermore, using the calculated molecular volume, the dielectric constant for 1-propyl-3-methylimidazolium tetrafluoroborate was estimated by the method proposed by Singh et al. (J. Phys. Chem. B, 2008, 112(41) 12968–12972). The results of the correlation of the ATPSs were in very good agreement with the experiment using NRTL-NRF and UNIQUAC-NRF models and gave more accurate results than the UNIQUAC model.

“…The literature report which published the [C 4 C 1 im]Br + Na 3 C 6 H 5 O 7 + water system found that lower temperatures are favorable for the formation of IL-ABS, whereas there are also some phase diagrams which were not affected apparently by the temperature . Another important aspect is the research studies concerning the influence of various salts on phase diagrams. , For example, the effect of salts on ABSs was evaluated by Mara and his group. , It was demonstrated that the additive salt only slightly affected the phase equilibrium of two-phase aqueous solutions, and the ILs play a more important role in causing the phase separation . Therefore, appropriate cations and anions of the ILs can be chosen to study the reason for the various abilities of different systems to form ABSs.…”

Section: Introductionmentioning

confidence: 99%

“…16 Another important aspect is the research studies concerning the influence of various salts on phase diagrams. 17,18 For example, the effect of salts on ABSs was evaluated by Mara and his group. 19,20 It was demonstrated that the additive salt only slightly affected the phase equilibrium of two-phase aqueous solutions, and the ILs play a more important role in causing the phase separation.…”

Section: Introductionmentioning

confidence: 99%

Influence of Ions and Temperature on Aqueous Biphasic Systems Containing Ionic Liquid and Ammonium Sulfate

Zhu

Luo

et al. 2019

Recently, ionic liquids (ILs) were widely used to form aqueous biphasic systems (ABSs). In this study, a systematic investigation involving various ILs was studied to provide more information on forming IL-ABSs. For this purpose, based on the IL cations, n-butylpyridinium trifluoromethanesulfonate, n-butylpyridinium tetrafluoroborate, and nbutylpyridinium nitrate, the influence of anions of the IL on forming ABSs was evaluated. The cation effect between 1-nbutyl-4-methylpyridinium tetrafluoroborate and n-butylpyridinium tetrafluoroborate was discussed. Besides, bimodal curves data of all the studied ABSs were measured and presented. The binodal curves were then correlated by the Merchuk equation with values of R 2 > 0.9966, which is widely used to fit the binodal curves. Moreover, the influence of temperature on ABSs was studied for [4-MBP]BF 4 + (NH 4 ) 2 SO 4 + water. The two-phase region in the diagram is found to increase as the temperature decreases.