Journal of Solution Chemistry最新文献

Hydroxamic acids (N-hydroxyamides) are relevant as ligands for metal ions, which are usable in agriculture and medicine and also present in nature. Their acidity constants in aqueous systems are needed to rationalize their metal ion complexation behaviour and parametrize-related prediction models. In this study, a detailed methodology is presented for determining the acidity constants (pK_a values) in water using a combination of nuclear magnetic resonance (NMR) spectroscopy with potentiometry. It includes the acidity constants of five N-hydroxyamides, two N-hydroxyimides and three other compounds: 1H-1,2,3-benzotriazole, 4-hydroxy-3-methoxybenzoic acid (vanillic acid) and pyrrolidine-2,5-dione (succinimide). Besides directly measured absolute pK_a values of the individual compounds, relative acidity (∆pK_a) measurements between pairs of compounds were carried out as well, resulting in a pK_a “ladder”, i.e. a system, where all acids were linked together by ΔpK_a measurements. The absolute and relative measurement results were combined together to improve the results’ reliability. As a result, twelve reliable pK_a values are now available, of which three have not been reported previously.

This study focuses on the analysis of the absorption spectra of cobalt(II) nitrate and cobalt(II) bromide complexes in the xCa(NO₃)₂–(1 − x)NH₄NO₃–H₂O system. Measurements were conducted within the wavelength range of 400–800 nm, at a constant temperature of T = 328.15 K and atmospheric pressure of p = 101.3 kPa. The spectra were recorded for systems with a fixed salt composition of 0.3Ca(NO₃)₂–0.7NH₄NO₃–H₂O, but with varying water content, described by the mole ratio of water to salt (R = H₂O/salt), where R was set to 1.0, 1.2, and 1.6. Additionally, the study investigated systems with varying calcium nitrate-to-ammonium nitrate ratios, represented as xCa(NO₃)₂–(1 − x)NH₄NO₃–H₂O, where x takes the values 0.3, 0.4, and 0.6. In these systems, the mole ratio of water to total salt was kept constant at R = 1.6. For systems with x = 0.7 and 0.9, a higher water-to-salt mole ratio of R = 3.6 was used. The analysis of absorption spectra revealed a shift of the maximum absorption peak toward shorter wavelengths (blue shift) as the water content (R) increased. This behavior suggests that both water molecules and nitrate ions participate in the coordination around the cobalt(II) ion. Based on the spectral data, the presence of the following complexes was confirmed: [Co(NO₃)₄(H₂O)₂]²⁻, [Co(NO₃)₂Br₂]²⁻ and [CoBr₄]²⁻. The overall stability constants of these complexes were calculated, and the corresponding resolved spectra of the species were determined at T = 328.15 K.

In this study, the solubility of glibenclamide was examined in binary solvent mixtures of 1-propanol/2-propanol and propylene glycol mixtures at temperatures between 298.2 K and 313.2 K. The solubility values were measured using a shake-flask method, with concentrations determined using a UV–Vis spectrophotometer. In these mixtures, the lowest solubility of glibenclamide was observed in neat PG at with solubility increasing as the temperature rises. Also, the highest solubility was recorded at the 1-propanol/2-propanol mass fraction of 0.6 and 0.5 and solubility increases with increasing temperature. The obtained solubility data were correlated by mathematical models, including the van’t Hoff, Jouyban–Acree, Jouyban–Acree–van’t Hoff, mixture response surface, and modified Wilson models and results showed high accuracy with low MRDs% (< 3.5%). Moreover, the density values for saturated mixtures were measured and represented by the Jouyban–Acree model with MRD% of 0.2 for both systems. The experimental data for glibenclamide dissolution at different temperatures can be used for computation of the thermodynamic properties, such as ΔG°, ΔH°, ΔS°, and TΔS°. These properties provide important insights into the energetic aspects of the dissolution process and were calculated using the van’t Hoff and Gibbs equations.

Standard transfer Gibbs free energies, (Delta G_text{t}^{0} (i)) and entropies, (Delta S_text{t}^{0} (i)) of four DNA and RNA bases, i.e., adenine (A), thymine (T), cytosine (C) and uracil (U) at 298.15 K from water to aqueous mixtures of acetonitrile (ACN) have been assessed using least square method from solubility quantifications at five equi-separated temperatures from 288.15 to 308.15 K under pressure 0.1 MPa. The observed variation of (Delta G_text{t}^{0} (i)) and (TDelta S_text{t}^{0} (i)) with composition of such protic and dipolar aprotic solvent mixtures are problematical to understand due to involvement of several interactions. Deduction of the cavity effect computed with Scaled Particle Theory and effects caused by dipole–dipole, dipole–induced dipole interactions agreed to the corresponding effects as controlled by chemical interactions between solutes and solvent molecules. Elimination of the associated dispersion interactions from chemical interactions generated the corresponding effects as directed by the hydrophilic and hydrophobic locations of the solutes with the components of the solvent mixtures compared to that in water. In the event of transfer entropies however, the corresponding interaction effects are also trickier than transfer Gibbs free energies due to the effect of the parallel structuredness of solvents. However, the complete behaviour of transfer Gibbs free energy, reflecting increased solvation of DNA-RNA bases, points us to conclude that acetonitrile as dipolar aprotic solvent accelerates denaturation of double-stranded nucleic acid helix.

The solubility of 3,4,5-Trimethoxyphenylacetonitrile (TMB) was measured by employing a static gravimetric method in twelve pure solvents (methanol, ethanol, n-propanol, iso-propanol, n-butanol, 2-butanol, n-hexane, cyclohexane, n-heptane, ethyl acetate, iso-propyl acetate, N,N’-dimethyl formamide (DMF)) with the temperature ranging from 283.15 to 323.15 K under the atmospheric pressure. The experimental results demonstrated that the mole fraction solubility of TMB increased with the increasing temperature in all systems, and the solubility of TMB is the highest in DMF and lowest in n-heptane. The experimental solubility of TMB was fitted using the modified Apelblat, Wilson, Yaws, and λh models. And the experimental data were agreed well with these models. Furthermore, the results show that the best fitting model was the modified Apelblat model with an average relative deviation of less than 1%. The intermolecular forces between solute and solvent were evaluated by the cohesive energy density obtained by molecular dynamics simulation, and the solubility and compatibility of solute and solvent were predicted. The analysis of Hansen solubility parameters was performed to investigate the similarities between solvents and TMB, thereby improving our understanding of their dissolution behaviors. The thermodynamic properties of the dissolution process are also calculated using the Wilson model. The results show that the dissolution of TMB is an endothermic process driven by enthalpy.

Isopiestic molalities of the system CsCl–MgCl₂–H₂O at 428 K are reported. The isopiestic apparatus and details of the measuring procedure are described. MgCl₂ served as reference electrolyte. Its water activity was calculated with the extended Pitzer model of Wang and Pitzer [J Phys Chem Ref Data 27(5):971–991, 1998]. For the binary system, CsCl–H₂O osmotic coefficients have been fitted at 298, 373, and 428 K using data from literature and of this work. The variation of the rational activity coefficient of water with temperature and concentration is explained by the effect of structure-breaking, ion association, and hydration. The isopiestic molalities in the ternary system show strong positive deviations from Zdanovskii’s rule. Empirical interpolation equations are applied to calculate the water activity at given total molality and mole fraction of CsCl. At molar ratios H₂O/MgCl₂ < 8, water-anion exchange in the coordination sphere of Mg²⁺ governs the variation of the water activity.

Numerous studies have highlighted the advantages of combining different advanced oxidation processes (AOPs) for wastewater treatment to enhance the degradation of organic pollutants. In this context, the classic Fenton and photo-Fenton processes were studied and compared for the oxidation of Acid Fuchsin dye. The effects of operational conditions such as stirring speed, pH of the medium, ferrous ion and hydrogen peroxide concentrations, and reaction time were investigated. The results showed that the UV/Fe²⁺/H₂O₂ system increased dye degradation while reducing the amount of chemicals and reaction time compared to the classic Fenton process. A maximum oxidation percentage of 93.84% % was achieved within 20 min of reaction under UV radiation (λ = 254 nm) at pH 3, [Fe²⁺]₀ = 0.18 mol·m⁻³, and [H₂O₂]₀ = 0.06 mol·m⁻³, while only 84.56% of dye molecules were degraded using the Fe²⁺/H₂O₂ system under the same conditions. In light of these results, the photo-Fenton process can be effectively used for textile wastewater treatment.

This study investigates the volumetric and acoustic properties of the local anesthetic drug mexiletine hydrochloride in aqueous and aqueous NaCl media over a temperature range of T = (288.15–313.15)K. Volumetric and acoustic properties are essential for understanding solute–solute and solute–solvent interactions in solution. In this study, we measured the density and speed of sound for a binary aqueous solution of mexiletine hydrochloride in the concentration range of (0.01–0.15) mol·kg⁻¹ and a ternary aqueous solution containing a fixed concentration of 0.06 mol·kg⁻¹ of sodium chloride as solvent. These data were used to calculate the apparent molar volume of the solute ((V_{phi })), the isentropic compressibility (κₛ) of the solutions, and the apparent molar isentropic compressibility (κ_φ) of the solute concerning drug concentration. The variation in temperature data allowed us to calculate the apparent molar expansivity ((E_{phi })) and limiting expansivity ((E_phi^0)) in infinitely dilute solutions at selected temperatures. Hepler's constant provides insight into a structure-breaking ability through negative values. The favorable result implies that mexiletine hydrochloride, with negative values, promotes structure formation in water and aqueous NaCl solutions. The negative readings indicate that mexiletine hydrochloride is structurally unstable at this temperature. That mexiletine hydrochloride exhibits strong hydrophilic and ionic interactions, with negative compressibility values highlighting a robust hydration structure. The presence of NaCl enhances solvation and reduces compressibility, suggesting significant structural changes in the solvent. These findings provide critical insights into the physicochemical behavior of mexiletine hydrochloride in biologically relevant environments, contributing to its pharmaceutical and biochemical applications. The hydrophilic–ionic and hydrophilic–hydrophilic interactions present in the systems are used to explain the trends observed in parameter variation for both experimental and computational data. We also discuss the results regarding ion–solvent interactions in binary solutions and the effect of adding sodium chloride on these interactions.

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This review article considers the properties of the homologous series of ethoxylated monoalkylphenols C₉H₁₉C₆H₄O(C₂H₄O)_nH with degrees of oxyethylation from n = 2 to n = 12, which are effective nonionic surfactants for cloud point extraction. The results of cloud point measurements of aqueous solutions of pure ethoxylated monoalkylphenols, in their mutual mixtures, in the presence of sodium salts, depending on the concentration of the surfactant and the balance of surfactants in binary mixtures are discussed. Based on the results of self-diffusion coefficient measurements, the effective radii of micelles and dehydrated aggregates of surfactants near and above the turbidity region are calculated, and the phenomenon of oxyethylene chain contraction is discussed. The efficiency of phenol CPE was measured by NMR spectroscopy, the effect of electrolytes and the composition of mutual mixtures of surfactants on increasing the efficiency of CPE and reducing the process temperature to room values ​​was analyzed. The CPE method is an effective, environmentally friendly method of wastewater treatment, and the homologous series of ethoxylated monoalkylphenols are excellent nonionic surfactants for it.

Anthranilic acid (2-amino benzoic acid), a medicinally important compound, is derived from indigo dye (extracted from Indigofera tinctoria) exhibits potential to form complexes with transition metals. We have used sodium salt of anthranilic acid as anion to prepare a new, C₂-symmetrical, third-generation, hydrophobic task-specific Ionic Liquid (IL); dioctylimidazolium anthranilate [DOIM][AN] and successfully investigated its ability to selectively extract Co²⁺ and/or Ni²⁺ from their aqueous solutions. Co²⁺ and Ni²⁺, both exhibit similar physical and chemical properties. The IL showed good efficiency in the separation of Co²⁺ and Ni²⁺ from their aqueous solutions within five minutes at room temperature. The IL was recycled under basic conditions and reused. The extraction efficiencies were determined through Atomic Absorption Spectroscopy (AAS). The characterization of IL was done through Electron Spray Ionization Mass spectroscopy (ESI–MS), Nuclear Magnetic Resonance (NMR), and Infrared spectroscopic (IR) techniques. The rheometric analysis revealed that IL has Newtonian-type behavior.