Journal of Solution Chemistry最新文献

The three-parameter extended Hückel equations with parameters B, b₁, and b₂ have recently been successfully tested against existing vapor pressure, electrochemical, and solubility data for aqueous NaCl solutions at temperatures from (273 to 373) K (Partanen and Partanen in J. Chem. Eng. Data 65:5226–5239, 2020). In the present study, we extend this model to the apparent and partial molar enthalpy data of these solutions. The enthalpy equations were determined using a new calculation method that gives practically the same results as that used in another previous study (Partanen et al. in J. Chem. Eng. Data 62:2617–2632, 2017), but the new method is much simpler. In the previous enthalpy study, dilute NaCl solutions up to m = 0.2 mol⋅kg⁻¹ were considered in the range from T = 273 to 353 K. Following the success of the three-parameter extended Hückel model within the whole concentration range at various temperatures, we tabulate new values for relative apparent and partial molar enthalpies for NaCl solutions at rounded molalities. The resulting values are extensively tested against the literature ones. The best agreement is obtained for temperatures below 288 K and between 313 and 353 K. Elsewhere, at least a reasonable agreement is obtained. As no enthalpy or heat capacity data were used in the estimation of our model’s parameters and as the model has excelled in explaining other high-precision thermodynamic data, we argue that the recommended enthalpy values should be preferred even for the temperatures where the agreement is only reasonable due to potential problems associated with the literature values. These problems are also considered in the study.

Graphical Abstract

Critical temperature, critical pressure and P–T–ρ–X data of acetone–water solutions with water mole fractions in a range of 0–60% were measured to provide fundamental data for CFD simulations. Critical temperatures were determined via observing critical opalescence in fused quartz capillary tubes. Meanwhile, critical pressures were measured by heating acetone–water solutions to its critical temperature in an autoclave. The standard deviations of critical temperature and critical pressure were 0.55 K and 0.029 MPa, respectively. The results indicate that only one phase exists during mixing of acetone with water. Moreover, P–T–ρ–X data under 15 and 20 MPa in the temperature range of 460–550 K were measured in the autoclave. The relative deviation of density was 0.32%. Volume-translated Peng-Robinson and Soave–Redlich–Kwong state equations were used to illustrate the P–V–T–X relationship of acetone–water solutions, and the Peng–Robinson state equation with an average absolute relative deviation of 1.19% between fitting and experimental densities was found more accurate.

The complexation between Al³⁺ ([Al(H₂O)₆]³⁺) and glycolic acid (GA, C₂H₄O₃) which has a carboxyl group and a hydroxyl group in a molecule was investigated under acidic condition using ²⁷Al NMR, ¹³C NMR and ESI–MS techniques. The five peaks including a peak due to Al³⁺ were observed in ²⁷Al NMR spectra for the mixed solution of Al³⁺ and GA, suggesting the existence of at least four Al-GA complexes. The results of NMR and ESI–MS measurements revealed that GA and Al³⁺ can form one monodentate complex (AlGA²⁺) and three bidentate complexes (AlGA⁺, AlGA₂⁻, and AlGA₃³⁻) complexes. From the deconvolution of ²⁷Al NMR spectra and pKa value of GA, the conditional formation constants (log₁₀ K) of each complex (GA/Al molar ratio of 25 in mixed solution) can be determined to be 0.94 (AlGA²⁺), − 0.96 (AlGA⁺), − 0.77 (AlGA₂⁻) and − 2.21 (AlGA₃³⁻), respectively. In addition, the overall formation constant of three bidentate complex at pH 3 was also calculated to be − 1.65.

Three imidazole anion-functionalized ionic liquids (IFILs) with tributylethylphosphonium ([P₄₄₄₂]⁺) cation and imidazolate ([Im]⁻), 4-methylimidazolate ([4-MeIm]⁻), or 4-bromimidazolate ([4-BrIm]⁻) anions were prepared to study the effect of physicochemical properties on CO₂ absorption behavior. Density (ρ), viscosity (η), and speed of sound (u) of the studied IFILs were measured, and molecular volume (V_m), standard entropy (S⁰), lattice energy (U_POT), and isentropic compressibility coefficient (κ_s) were calculated accordingly. CO₂ absorption behavior of [P₄₄₄₂][Im] at T = 313.15–333.15 K and p = 0.2 and 1 bar was investigated as an example. The results show that with the increase of temperature, ρ, η, u, and U_POT decrease, while V_m, S⁰, and κ_s increase, due to a decrease in electrostatic interaction correspondingly. The orders of ρ, u, η, V_m, and S⁰ values are as follows: [P₄₄₄₂][Im] < [P₄₄₄₂][4-MeIm] < [P₄₄₄₂][4-BrIm], while U_POT and κ_s are in reverse order. Interestingly, CO₂ capture capacity of IFILs is approximately linear with η or κ_s. Due to low η and high κ_s, CO₂ absorption capacity of [P₄₄₄₂][Im] is almost independent of temperature and partial pressure, as high as 0.90 mol CO₂/mol IL at 333.15 K and 0.2 bar, indicating that [P₄₄₄₂][Im] has potential applications for CO₂ absorption at high temperature and low pressure.

Vapor–liquid equilibrium data of binary systems (water + acetic acid, isopropanol + water, and acetic acid + isopropyl acetate), and ternary systems (water + acetic acid + 1-sulfobutyl-3-methylimidazolium hydrogen sulfate (ionic liquid, [HSO₃-bmim][HSO₄]), isopropanol + water + [HSO₃-bmim][HSO₄], and acetic acid + isopropyl acetate + [HSO₃-bmim][HSO₄]) were determined at 101.33 kPa. The nonrandom two-liquid (NRTL) model fitted well with the experimental data. The σ-profiles of water, acetic acid, isopropanol, isopropyl acetate, [HSO₃-bmim]⁺, and [HSO₄]⁻ were calculated using the COSMO-RS model. Furthermore, the binding abilities of [HSO₃-bmim][HSO₄] ionic liquid with water, acetic acid, isopropanol, and isopropyl acetate were analyzed by σ-profiles. The chemical and phase equilibrium data of acetic acid + isopropanol, and acetic acid + isopropanol + [HSO₃-bmim][HSO₄] systems were determined, meanwhile, the chemical equilibrium constant K_r was calculated. These results provided basic thermodynamic data for [HSO₃-bmim][HSO₄] as the catalyst for the esterification system of acetic acid with isopropanol.

The solution enthalpies of tetra-methyl- and tetra-butyl-ammonium tetrafluoroborates were measured using solution calorimetry. The sublimation enthalpies and vaporization enthalpies of ammonium-based ionic liquids with the anions [BF₄] and [NO₃] were derived from temperature dependencies of the vapour pressures, measured with a quartz crystal microbalance and adjusted to the reference temperature 298.15 K. The solution calorimetry results were used to derive the solid-phase enthalpies of formation of the compounds studied. The latter results were combined with the sublimation enthalpies to obtain the experimental gas-phase formation enthalpies of the ionic liquid containing [BF₄] and [NO₃] anions. The theoretical gas-phase formation enthalpies were calculated using the quantum chemical method G3MP2 and agree well with the experimental results. Different types of structure–property relationships were used to establish the consistency of the alkyl-ammonium-based ionic liquids studied in this work.

Sulfuric acid (({text{H}}_{2}{{text{SO}}}_{4})) is one of the most widely used chemicals, acting as a reagent in several industries and metallurgy. The chemical behavior in aqueous solutions can be as strong or weak if the acid concentration is low or high, respectively. The aim of this work is the estimation of the thermodynamic properties and to predict the speciation, density and ionic conductivity of aqueous sulfuric acid solutions up to 6 molal and 0–100 °C, using the Pitzer model adapted to include the interaction parameters of sulfate complexes as ({text{HSO}}_{4}^{-}) and ({text{H}}_{2}{text{S}}{text{O}}_{4}^{0}). A thermodynamic model that includes a set of aqueous species, components, equilibrium reactions, activity coefficients, and mass balances was defined as a function of temperature. The parameters of the equilibrium constants for ({text{HSO}}_{4}^{-}) and ({text{H}}_{2}{text{S}}{text{O}}_{4}^{0}), the Equation of State (EOS) HKFmoRR for solution density, the Casteel–Amis relationship for ionic conductivity, and the Pitzer model for water activity were combined by coupling of the optimization software PEST with the hydro-geochemical code PHREEQC. The Pitzer model was calibrated and resulting in a standard deviation of water activity adjustment of 0.7%. Sulfuric acid distributes in water forming common anions, cations, and neutral species as ({text{SO}}_{4}^{{2}-}), ({text{HSO}}_{4}^{-}), ({text{H}}^{+}), and ({text{H}}_{2}{text{S}}{text{O}}_{4}^{0}), where the association of sulfate increase with both electrolyte concentration and temperature. The solution density and ionic conductivity calculations were in good agreement with experimental data, presenting a standard deviation of adjustment of 0.2 and 4.8%, respectively, over the temperature and concentration ranges studied.

An environmentally benign aqueous two phase system has been developed for the separation of ^108mAg from ¹⁵²Eu and ⁶⁰Co using polyethylene glycol/salt system. Twelve salts (nine inorganic, three organic) and PEG 4000 were chosen to form the ATPS out of which, the best separation was observed for 3 mL 2 mol·dm⁻³ K₃PO₄: 3 mL PEG 4000 followed by 3 mL 2 mol·dm⁻³ Na₂SO₄: 3 mL PEG 4000. In both cases, silver was preferentially extracted in the PEG rich phase. The separation factors achieved were S_Ag/Co = 2.11 × 10³ and S_Ag/Eu = 2.79 × 10² in the case of 2 mol·dm⁻³ K₃PO₄: PEG 4000 combination.