New ATPSs Containing Choline Salts and Propan-1-ol: Phase Equilibria, eNRTL Modeling, and Partitioning Studies
Industrial & Engineering Chemistry Research, 2025
"In this work, the liquid–liquid equilibria (LLE) of the Aqueous Two-Phase Systems (ATPSs) {propa... more "In this work, the liquid–liquid equilibria (LLE) of the Aqueous Two-Phase Systems (ATPSs) {propan-1-ol (1) + choline bicarbonate ([Ch][Bic]) or choline dihydrogen citrate ([Ch][H2Cit]) (2) + water (3)} were assessed at 298.15 K and 0.1 MPa. Solubility curves were estimated by the “cloud-point” method, while tie-line composition data were determined using third-degree polynomials of liquid density (ρ) and electrical conductivity (κ). The obtained LLE data were correlated with low standard deviations (σ_SD) using various empirical models, such as the ones of Han et al. for solubility data (3.8 < σ_SD × 10^3 < 11) and Bancroft-Hubard for tie-line composition data (3.4 < σ_SD × 10^2 < 4.6). Tie-line composition data were also described with the electrolyte-Non-Random Two-Liquid (eNRTL) model, considering the ATPSs as mixed solvent media with strong salts and obtaining low standard deviations (7.3 < σ_SD × 10^7 < 7.7). Although very successful, this modeling approach required a significant number of adjustable parameters to describe all the interacting species, which may be intensive from a computational point of view. Moreover, during thermodynamic modeling, nonrandomness factors based on calculations at the Density Functional Theory (DFT) level were applied for propan-1-ol (α = 0.1970) and water (α = 0.3333), while a fixed value was used for the choline salts (α = 0.2). Finally, to demonstrate the practical potential of these ATPSs for removing pharmaceutical pollutants from water, partition studies of salicylic acid (Sa) were conducted in these systems, attaining promising partition coefficients (2.1 ± 0.3 < K < 5.6 ± 0.9) and extraction efficiencies (53 ± 2 < E / % < 87 ± 3), specially for the system containing [Ch][H2Cit] (4.4 ± 0.5 < K < 5.6 ± 0.9) and (77 ± 2 < E / % < 87 ± 3). Moreover, a positive effect on these performance indicators was observed with growing lengths of tie-line (TLLs), for which a significant affinity exists between the target solute and propan-1-ol."
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Papers by Pedro Velho
properties of mixtures containing ionic liquids is vital to promote the adoption of these chemicals in the recovery of valuable components, such as metallic ions, from waste. In this work, the liquid density, dynamic viscosity, shear stress, torque, electrical conductivity, and refractive index of binary mixtures composed of the phosphonium ionic liquid rihexyltetradecylphosphonium bis(trifluoromethylsulfonyl) imide (usually known as [P666,14][NTf2] or [THTDP][NTf2]) and ethanol were measured at different temperatures and 0.1 MPa. Liquid densities were accurately correlated by the Connors and Wright expression, presenting low standard deviations to experimental data and high determination coefficients (0.999984 < R^2 < 0.999988), while excess molar volumes were effectively represented by Redlich−Kister expansions (0.9841 < R^2 < 0.9869). On the other hand, dynamic viscosities were described using an Arrhenius linearization for binary mixtures (0.9611 < R^2 < 0.9995) and the Vogel−Fulcher−Tammann−Hesse (VFTH) equation for pure components (0.9972 < R^2 < 0.9975). Furthermore, the ionicity (or degree of dissociation, α) of the ionic liquid was determined using the Walden plot methodology, being practically independent of composition (0.134 < α < 0.191)."
used to describe tie-line composition, yielding low standard deviations in mole fraction basis (8.36 · 10^−4 < σ_x < 5.02 · 10^−2) while considering a fixed value of the nonrandomness factor (α = 0.3333)."
In this work, the liquid densities (ρ) of the binary mixtures of ethyl lactate or cholinium iso-leucinate with water or ethanol were determined at 288.15, 293.15, 298.15, 303.15 or 308.15 K and 0.1 MPa. Then, the calculated excess volumes were correlated with molar composition using three different methodologies: third-degree polynomials; Redlich-Kister expansions; and a novel approach based on computational chemistry (Density Functional Theory, DFT).
The standard deviation (σ) of these approaches to experimental data showed that the novel methodology, which relied on calculating molar volumes by combining B3LYP / 6-311++G(d) with the Integral Equation Formalism Polarizable Continuum Model (IEFPCM), obtained a better description of the binaries than third-degree polynomials and Redlich-Kister expansions. Moreover, this novel methodology was considered to decrease the number of adjustable parameters while, at the same time, providing a more concrete physical meaning to the parameters, enhanced accuracy and predictivity."
In this work, the liquid density (ρ) of five binary aqueous solutions of organic salts (disodium tartrate, sodium potassium tartrate, dipotassium tartrate, trisodium citrate and tripotassium citrate) were measured and correlated at 298.15 and 313.15 K and 0.1 MPa. In these assays, second-degree polynomials provided determination coefficients (R^2) larger than 0.9982 in the correlation of liquid density with salt molality, for which a very accurate description of this property was accomplished. Moreover, vapour pressure osmometry (VPO) studies were carried out for these solutions at 313.15 K and 0.1 MPa. Then, the obtained osmotic oefficients (ϕ) were successfully modelled using the Extended Pitzer Model of Archer, yielding standard deviations (σϕ) lower than 8.61⋅10^-3. Finally, the mean molal activity coefficients (γ±) and excess Gibbs free energies (GE/RT) of the binary aqueous solutions of organic salts were effectively calculated, with potassium- and tartrate-based salts attaining significantly higher values than the ones composed of sodium and citrate, hinting at a more ideal solution behaviour of the former."