Journal of Solution Chemistry最新文献

The kinetics of degradation of tetracycline hydrochloride by H₂O₂ in the presence of Cu–Fe₃O₄ nanoparticles were investigated. Copper-doped Fe₃O₄ nanoparticles were synthesized by mixing the required amount of FeCl₂, FeCl₃ and CuSO₄ solutions and then precipitation by adding the 30% NH₄OH solution dropwise. The dried and washed precipitates were characterized by using EDS, XRD, SEM and FTIR techniques. The EDS indicated the presence of Fe, Cu and O, whereas the XRD showed crystalline nanoparticles with average size of 20–25 nm. The FTIR confirmed the presence of Cu–O and Fe–O bonds. The kinetics of degradation of tetracycline hydrochloride (TC) were studied by spectrophotometrically under sonication at 40 °C. The addition of H₂O₂ and nanoparticles to the tetracycline hydrochloride solution resulted in the disappearance in the absorbance intensity of TC with time. The rate constant values were investigated at different concentrations of TC, H₂O₂, HCl, nanoparticles dosage, surfactants, etc. The peak-like curve was obtained for the plot of rate constant values versus the concentrations of H₂O₂, HCl and nanoparticles dosage. The nanoparticles catalyse the reaction by producing the ^·OH radicals on interaction with H₂O₂. These ^·OH radicals oxidize TC and, thus, helps to eliminate the TC molecules from the wastewater. The kinetics studies carried out in the presence of surface-active molecules like sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB), triton X-100 (TX100), polyvinyl alcohol (PVA), etc. demonstrated that the nanoparticle-H₂O₂ is effective in the degradation of TC in the presence of such contaminants.

Despite having significant pharmaceutical potential, many compounds are avoided by researchers due to their low solubility and high volatility. These characteristics make them difficult to manipulate and incorporate into drug formulations. Cyclodextrins solve this problem by increasing the solubility of bioactive molecules, making them easier to handle and significantly improving bioavailability. These macromolecules have a wide range of applications, including pharmaceuticals, agriculture, cosmetics, and the environment. This paper presents a computational study of an inclusion complex between verbenone and (beta -)cyclodextrin ((beta {-}text {CD})) with a 1 : 1 stoichiometry. The objective is to improve understanding of anomalies that were not identified during experiments and explain why verbenone forms a good complex with (beta -)cyclodextrin. This complex aims to increase verbenone solubility while decreasing volatility for maximum activity. The PM3 method was used to optimize the verbenone*(beta -)cyclodextrin complex as a first excess. The guest was oriented once toward the wide side of the (beta {-}text {CD}) (orientation A) and another toward the narrow side (orientation B), with inclusion simulation using hyperchem 8.0 software. After calculating the complexation energies and determining the optimal complexes, these complexes were re-optimized using density function methods: B3LYP, MN15, and MN15L with a base set 6-31 G(d,p) in gas and aqueous phases. Theoretical calculations were performed with Gaussian16 software, and visualization was carried out using Gaussview 6. According to the optimal 3D structures, the verbenone was fully encapsulated in the (beta {-}text {CD}) cavity. The complexation energies, HOMO-LUMO orbitals, and reactivity parameters were calculated. Their analysis confirms that the complex at orientation A is more stable and electrophilic than that at orientation B, and the charge is transferred from the host to the guest. Natural binding orbitals (NBO) were also analyzed. The QTAIM, RDG-NCI, and IGM analyses were interpreted to consider the non-covalent interactions that maintain stability between (beta {-}text {CD}) and verbenone. Data analysis and visualization were performed using Multiwfn and VMD. The chemical shifts of verbenone protons in the free and complex states were calculated and compared to experimental data. The findings show the formation of a complex between verbenone and (beta {-}text {CD}), which is stabilized by van der Waals and hydrogen interactions.

The phase separation of triton X-100 (TX-100) and polyethylene glycol-400 (PEG-400) mixtures was investigated in aqueous and aqueous solutions of hydrotrope-containing systems (anionic: sodium benzoate (NaBenz), sodium salicylate (NaSal); nonionic: 4-aminobenzoic acid (4-ABA), resorcinol (benzene-1,3-diol (BDL)), and nicotinsaureamid (pyridine-3-carboxamide (PyC))) using the cloud point (CP) detection technique. The magnitudes of CP for the TX-100 and PEG-400 mixed solution were examined with TX-100 concentration significantly above its critical micelle concentration (CMC), and experienced changes upon the introduction of various hydrotropes (HDTs). The solubility of the PEG-400 and TX-100 mixture was notably impacted by the HDTs studied. As the HDTs concentration raised, the CP values showed an upsurge trend (indicating enhanced solubility) for anionic HDTs (NaBenz and NaSal) and an nonionic HDT (PyC). In contrast, CP values decreased (indicating reduced solubility) in solutions of remaining two nonionic HDTs (4-ABA and BDL). At CP, the changes in standard free energy (({Delta G}_{text{c}}^{0})), enthalpy (({Delta H}_{text{c}}^{0})), and entropy (({Delta S}_{text{c}}^{0})) of the clouding were determined. The ({Delta G}_{text{c}}^{0}) values for the clouding process were positive, indicating the process is not spontaneous. The negative ({Delta H}_{text{c}}^{0}) of the clouding system in two nonionic HDTs, 4-ABA and BDL media, indicate exothermic clouding, whereas the other media was mostly endothermic in nature. The ({Delta H}_{text{c}}^{0}) and ({Delta S}_{text{c}}^{0}) values suggest that electrostatic (hydrogen bonding and dipole–dipole interactions) and hydrophobic forces dominate between TX-100 and PEG-400 during cloud formation. The thermodynamics properties of transfer (({Delta G}_{text{c},text{tr}}^{0}), ({Delta H}_{text{c},text{tr}}^{0}), ({Delta S}_{text{c},text{tr}}^{0})), compensation temperature (T_c), and intrinsic enthalpy gain (({Delta H}_{text{c}}^{0,*})) were calculated and thoroughly analyzed to elucidate the system’s behavior and interaction forces.

Graphical Abstract

This paper reports the Analytical Solutions of Groups (ASOG) for the prediction of liquid–liquid equilibria (LLE), i.e., ASOG-LLE. In this work, the fundamental group pair parameters of ASOG-LLE were determined from the experimental LLE data. To determine these parameters, we measured binodal curves and tie-line LLE data for ternary systems of heptane + alcohol (ethanol, 1-propanol, 2-propanol, and 1-butanol) + methanol at 303.15 and 298.15 K. The experimental tie-line LLE data were correlated using the NRTL model. ASOG-LLE parameters including CH₂, OH, H₂O, 1-PrOH, and 2-PrOH, as fundamental groups, were determined using our experimental LLE tie-line data with literature values for systems including alcohol + alcohol + alkane, alcohol + water + alcohol and alcohol + water + alkane. The predicted LLE results were compared with those based on the Universal Functional Group Activity Coefficient (UNIFAC)- LLE.

The aim of this work is to experimentally determine co-solvent effects on the solubility of a poorly water-soluble flavonoid. Naringin, a flavonoid glycoside, was studied as a model poorly water-soluble compound. Two surfactants (sodium lauryl sulfate and polyoxyethylene sorbitan monooleate (Tween 80)), and three cyclodextrins (CDs: β-CD, 2-hydroxypropyl-β-CD, and dimethyl-β-CD) were studied as co-solvents by measuring the solubilities of naringin at 298.15 K using high-performance liquid chromatography in water/co-solvent mixtures. The stability constants of the co-solvent/solute systems were evaluated by the Higuchi–Connors solubility method. According to these results, dimethyl-β-CD had the highest co-solvent effect among the CDs. Modeling of the experimental solubility data were performed using the modified Chrastil model.

In this study, we calculated the excess molar enthalpy (H_{m}^text{E}), of acetonitrile mixed with 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, trichloroethylene, and tetrachloroethylene using a calorimetric method at a temperature of 303.15 K and a pressure of 81.5 kPa with a Parr/1455 solution calorimeter. We also determined the excess partial molar enthalpies (overline{{H_{m,i}^text{E} }}), excess partial molar enthalpies at infinite dilution (overline{{H_{m,i}^{text{E},infty } }}), and the intermolecular interactions function (H_{i - i}^{{}}). The results were analyzed using the Redlich–Kister polynomial relation. Various local composition models, including Wilson, Universal Quasi-Chemical (UNIQUAC), and Non-Random Two-Liquid (NRTL) were investigated. The equation state of Prigogine Flory–Patterson (PFP), was also applied. Notably, acetonitrile showed exothermic behavior when mixed with 1,2-dichloroethane and 1,1,2,2-tetrachloroethane, whereas it exhibited endothermic behavior with 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene. Endothermic behavior (positive enthalpies of mixing) signifies that the actual enthalpy of mixing is higher than expected for an ideal solution, indicating repulsive interactions. In contrast, exothermic behavior (negative enthalpies of mixing) denotes that the actual enthalpy of mixing is lower than expected, suggesting attractive interactions.

The present communication reports the experimental measurements on the density ((rho )), speed of sound (u), and viscosity ((eta )) of binary liquid mixtures of 2-methyltetrahydrofuran (2-MTHF) with methyl acetate (MA), propyl acetate (PA), and pentyl acetate (PnA) at 298.15, 303.15, and 308.15 K and at ambient pressure 0.10 MPa. Using the experimental measured density and speed of sound values, excess molar volumes (({V}_{m}^text{E})), excess molar isentropic compressibility (({K}_{S,m}^text{E})), and excess in speed of sound (u^E) have been calculated. The deviation in viscosity (Δη) and excess Gibbs energy of activation of viscous flow (Δ ({G}^{*text{E}})) were evaluated using the experimental values of viscosity. The excess molar volumes, excess isentropic compressibility, excess in speed of sound, and deviation in viscosity data were fitted using a Redlich–Kister type equation. For the computed and experimental data, the standard deviation values are calculated. The viscosity data have been correlated with the equations of Tamura–Kurata, Grunberg–Nissan, Heric–Brewer, Hind et al., Katti–Chaudhri, and McAllister (four-body interaction) model. In addition, partial molar volumes of the 2-methyltetrahydrofuran with acetates have been determined in terms of the mole fraction concentration unit.

The phase transfer oxidant ethylenediammonium dichromate [enH₂Cr₂O₇] has been employed to investigate the kinetics of aliphatic aldehyde oxidation in a dimethyl sulfoxide medium. Rate constants were calculated in the temperature range 293 K–323 K under pseudo-first-order conditions concerning oxidant. The kinetics of the reaction are investigated using a conventional UV–Vis spectrophotometric technique. The order is less than two for the aldehydes, and the rate of reaction increases as the concentration of [H⁺] increases. The fractional order dependency with respect to aldehydes confirms the binding of oxidant and substrate to form a complex before the rate-determining step. The existence of a primary kinetic isotope effect, k_H/k_D = 5.22 at 313 K for acetaldehyde (ratio of rate constants for protio- and deuterio- acetaldehyde) indicated a C–H bond cleavage rather than C–C bond cleavage. Isokinetic temperature and several other thermodynamic parameters are studied. From the experimental data, the formation of an unstable cyclic transition state followed by intra-molecular hydride-ion transfer has been proposed. All the aldehydes are oxidized by the same mechanism, according to the linear isokinetic correlation. The oxidation product is the corresponding carboxylic acid.

A computational methodology is proposed for determining the A–P model nonpolar and polar solute parameters of solid organic compounds from measured molar solubility data. The methodology is illustrated using measured solubility for anthracene dissolved in 73 organic solvents of varying polarity and hydrogen-bonding character. The calculated solute parameters back-calculated the observed solubilities to within a standard deviation of 0.91 natural logarithmic units. A much smaller standard deviation of approximately 0.30 ln units was noted when using the Abraham solvation parameter model to predict the observed anthracene solubility data.

Available thermodynamic data for (NH₄)₂SO₄(aq) have been critically evaluated and used to parameterize an extended ion interaction (Pitzer) model. The model satisfactorily represents the available activity and thermal data from below the eutectic temperature to 110 °C. At near ambient temperatures (5–40 °C) the model accurately predicts the water activities in supersaturated solutions to about 30 mol·kg^–1. The model has been used to determine the solubility products of (NH₄)₂SO₄(s) from the eutectic temperature to 110 °C. Solubilities in the ternary Tutton salt forming systems (NH₄)₂SO₄–MgSO₄–H₂O, (NH₄)₂SO₄–FeSO₄–H₂O, (NH₄)₂SO₄–ZnSO₄–H₂O, and (NH₄)₂SO₄–CuSO₄–H₂O have been used to determine the ternary interaction parameters in the Pitzer model and to calculate the solubilities and deliquescence humidities of the Tutton salts (NH₄)₂M^IISO₄·6H₂O (with M = Mg, Fe, Zn, Cu). Using additional literature data of decomposition vapor pressures, the phase diagrams of the Tutton salts have been established and the suitability of the salts as thermochemical heat storage materials has been critically evaluated.