Journal of Solution Chemistry最新文献

The zinc boron complex formation was studied as a function of temperature (25, 50 and 70 °C) in boric acid solutions of various concentration (0.25, 0.50 and 0.68 mol·kg⁻¹). pH was monitored during zinc ion addition by galvanostatic dissolution of a zinc metal electrode, in a solution of boric acid. The determination of the complex formation showed the importance of an accurate model of the polyborate speciation, recalculated for this work based on the previous literature data mainly potentiometric measurements completed by Raman spectroscopy and Ab Initio calculations. Modelling of our experimental results, considering various scenarios of boric acid speciation, was performed using R and PhreeqC, suggesting the formation of an aqueous triborate-zinc (II) complex, ({{text{ZnB}}}_{3}{{text{O}}}_{3}{({text{OH}})}_{4({text{aq}})}^{+},) according to the reaction: ({{text{Zn}}}^{2+}+3{{text{B}}({text{OH}})}_{3} rightleftharpoons {{text{ZnB}}}_{3}{{text{O}}}_{3}{({text{OH}})}_{4({text{aq}})}^{+}+2{{text{H}}}_{2}{text{O}}+{{text{H}}}^{+}). The nature and structure of this aqueous complex disagrees with the results reported previously in the literature. Three formation constants of the triborate-zinc (II) complex were determined at 25, 50 and 70 °C as ({{text{log}}}_{10}{K}_{text{ZnB}}) = − 4.73 ± 0.10, − 4.21 ± 0.16 and − 4.94 ± 0.12, respectively. The evolution of zinc boron complex formation as a function of temperature (between 25 and 70 °C) provides information on the effect of the polyborate predominance in the solution on the complexation of zinc.

Abstract

In a binary liquid mixture containing pyrimidine-substituted azetidinone ultrasonic velocities, densities, and viscosities have been measured by unit of molality azetidinone at temperatures T = (298.15, 308.15, and 313.15 K). 3-chloro-4-(4-nitrophenyl)-1-(pyrimidin-2-yl)azetidin-2-one (AT₁) and 3-chloro-4-(4-chlorophenyl)-1-(pyrimidin-2-yl)azetidin-2-one (AT₂) in N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) were studied. The density, dynamic viscosity, and ultrasonic sound velocity have all been measured, among other acoustical and thermodynamic properties. Gibbs free energy of activation (ΔG*), enthalpy of activation (ΔH*), and entropy of activation (ΔS*) values have been studied further to determine how solvent changes and structural modifications impact these values. The molecular interactions between the components of the liquid combination have been used to explain these findings.

Titrimetric methods were used to estimate the molar solubility and apparent acid dissociation constant (K_c) of salicylic acid in water. This was done with varied ionic strength values ranging from 0.00 to 0.75 mol·L⁻¹ and over a temperature range of 15 to 60 °C. The thermodynamic dissociation constant (as pK_a) of salicylic acid was found to be 2.985 at 25 °C. Within the measured temperature range, there was no consistent association between the pK_a of salicylic acid and the temperature. The pK_a values exhibited an inverse relationship with temperatures between 15 and 40 °C, while they showed a direct relationship with temperatures between 40 and 60 °C. Through the use of the Van’t Hoff plot, the standard thermodynamic quantities (∆H°, ∆S°, and ∆G°) for the dissociation process of salicylic acid in water were calculated. For temperatures between 15 and 30 °C, these values were determined as 3.346 kJ·mol⁻¹, − 19.99 JK⁻¹·mol⁻¹, and 9.306 kJ·mol⁻¹ respectively. For the temperature range of 45 to 60 °C, the values were calculated as − 1.499 kJ·mol⁻¹, − 27.06 kJ·K⁻¹·mol⁻¹, and 6.564 kJ·mol⁻¹. The heat of solution (∆H^°_sol) was computed using the Van’t Hoff Isochore plot across the temperature range of 15 to 60 °C, resulting in a value of 15.03 kJ·mol⁻¹.

Abstract

pH and thermo-sensitive polymeric nanoparticles with different morphology were synthesized by means of emulsion polymerization techniques. The materials were characterized by gravimetric techniques, dynamic light scattering (DLS), electrophoresis, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-Ray diffraction (XRD). The specific volumetric thermodynamic properties were calculated from density (ρ) and sound velocity (u) measurement and they are influenced by the proportions and location of the functional groups in the polymeric particles and the temperature. Rheological properties were also measured, observing that polymeric materials were a non-Newtonian and pseudo-plastic behavior because of they have a decrease in viscosity (left(eta right)) values as the shear rate rises  (left(dot{gamma }right)) . In addition, to try to elucidate the behavior that the materials could have with calcite rock in the oil reservoirs, the materials were treated with CaCl₂, and changes in the average particle size, colloidal stability and conformation of polymeric chains were observed. The obtained results show that the synthesized polymeric particles could be applied as a possible dosing agent in the interaction with calcium ions (Ca²⁺) in the calcite rock for petrol industry.

In the present work, the density, speed of sound, and refractive index of binary mixtures of propiophenone (PP) with 3-amino-1-propanol (AP), propylamine (PA), or isobutanol (IB) were measured over whole composition range at temperatures 298.15 to 308.15 K and ambient pressure (0.1 MPa). From these experimental data the excess molar volume, ({V}_{text{m}}^{text{E}}), excess isoentropic compressibility, ({kappa }_{text{S}}^{text{E}},) and excess refractive index, ({n}_{text{D}}^{text{E}}), were calculated. The calculated excess molar properties were correlated by Redlich–Kister equation, and their coefficients and standard deviations were calculated. The results show that the ({V}_{text{m}}^{text{E}}) values of PP + AP are positive in the entire composition range and at all temperatures, while the ({V}_{text{m}}^{text{E}}) values of PP + PA and PP + IB mixtures are negative over whole composition range and at all temperatures. The obtained ({V}_{text{m}}^{text{E}}) values were also correlated by Prigogine–Flory–Patterson (PFP) theory which show good agreement between experimental and predicted data.

In aqueous acetic acid medium, the kinetics of oxidation of glycolic and lactic acid by ethylenediammonium dichromate [enH₂Cr₂O₇] have been explored. The oxidation product is the corresponding oxoacid. The conventional UV–vis spectrophotometric method is used to study the reaction kinetics. First-order kinetics has been observed concerning [enH₂Cr₂O₇] and with substrate the order is less than two. The fractional-order dependency with respect to substrate confirms the binding of oxidant and substrate to form a complex before rate-determining step. The rate of reaction increases with an increase in [H⁺] concentration. The existence of primary kinetic isotope effect, k_H/k_D = 5.97 at 298K for glycolic acid (ratio of rate constants for protio- and deuterio-glycolic acid) indicated a C–H bond cleavage rather than C–C bond cleavage. Variation of solvent polarity is found to impose a remarkable impact on the rate of oxidation. From the experimental data, formation of an unstable cyclic transition state followed by intra-molecular proton transfer has been proposed. Under similar conditions oxidation of lactic acid was studied.

In order to separate phenol from water, at 101.3 kPa, the liquid-liquid equilibria (LLE) data of water + phenol + solvents (trichloromethane, isoamyl alcohol) were obtained at 298.15, 303.15, and 313.15 K. The ability of the extractant to extract phenol from water was evaluated by the distribution coefficient (D) and selectivity coefficient (S). The Bachman and Hand equations were used to verify the reliability of the LLE data with the linear coefficient was greater than 0.98%. The LLE data was correlated with the NRTL and UNIQUAC models to obtain a binary interaction parameter with an RMSD not greater than 0.36%.

The solubilities of the α-amino acids; DL-Tyrosine, DL-Leucine, DL-Isoleucine and DL-Threonine in six compositions of the binary mixture of pure water and dipolar aprotic N,N-dimethylformamide are evaluated by applying ‘analytical gravimetric’ method at nine equidistant temperatures in the range of 278.15 K to 318.15 K under 0.1 MPa pressure. Powder X-Ray diffraction and thermogravimetric analysis are performed to investigate solvate formation in saturated solutions. The equilibrium solubility values are compared with other literature and discussed. The variation of experimental solubility values in all compositions of such binary solvent mixtures at the experimental nine different temperatures are analysed in the light of chemical interactions involved. The standard molar dissolution Gibbs free energy, enthalpy and entropy are computed using the van’t Hoff analysis. The computed values of the same indicate that the process is endothermic. The standard molar Gibbs free energy as controlled by chemical, hydrophilic and hydrophobic interactions, imparts dissolution of the amino acids in the order, DL-Thr > DL-Ile > DL-Leu > DL-Tyr, as induced by the significant roles of side chains of such amino acids.

Methyl acrylate has a wide range of uses, but the production process usually produces aqueous by-products. In this study, four commonly used alcohols (1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol) were selected as extractants to explore the liquid–liquid extraction behavior of water + methyl acrylate + extractants. Through the analysis of partition coefficient (D) and separation coefficient (S), it is found that the data of all systems are greater than 1, indicating that all four alkyl alcohols can well separate methyl acrylate from aqueous solution, and 1-octanol is the best. In addition, the consistency between the binary interaction parameters of regression and tie-line data was tested using Matlab tools, proving that the obtained parameters have good consistency.

To fully understand the metallogenic regularity and the geochemical equilibrium rules of brine migration and transformation among potassium, barium and strontium in gas field water, the isothermal dissolution equilibrium method was used to study the phase equilibria of quaternary system KCl + BaCl₂ + SrCl₂ + H₂O and its two ternary systems BaCl₂ + SrCl₂ + H₂O and KCl + BaCl₂ + H₂O at 323 K. The equilibrium liquid phase compositions of each system was measured, the corresponding equilibrium solid phases were identified by chemical analysis and X-ray powder diffraction, and the equilibrium phase diagrams were drawn. No double salts or solid solutions were found in the ternary systems BaCl₂ + SrCl₂ + H₂O and KCl + BaCl₂ + H₂O at 323 K and the phase diagrams both contain one invariant point, two isothermal solubility curves and two crystallization regions. The hydrate forms in the quaternary system KCl + BaCl₂ + SrCl₂ + H₂O at 323 K are the same as those of its subsystems. The quaternary phase diagram contains one invariant point, three isothermal solubility curves and three crystallization regions, where the equilibrium solid phases are KCl, BaCl₂·2H₂O and SCl₂·6H₂O. These results provide basic thermodynamic data for the design of a comprehensive utilization process of potassium, barium and strontium resources in gas field water.