Hoff Equation Research Articles

(R,S)-Mandelic acid in pure and binary solvents solubility measurement and its correlation with thermodynamic models

In this study, The solubility of (R,S)-mandelic acid in different solvents, including mono-solvent (H2O, methanol, ethanol, n-propanol, isopropanol) and binary solvents (methanol + H2O, ethanol + H2O, n-propanol + H2O, isopropanol + H2O, n-butanol + H2O), using analytical stirred-flask method and weight analysis method to determine the compositions of the saturated solutions at the atmospheric pressure. We found that the experimental solubility values increased with the rising of temperature accordingly. The experimental solubilities were correlated by the Ideal model, Apelblat model, λh (Buchowski) model, Wilson model, NRTL model. The results have shown that the Wilson model is the best model, which correlates the solubility of (R, S)-mandelic acid in the mono-solvent and binary solvents and fits well with experimental data. In addition, the thermodynamic properties of dissolution were calculated according to Van’t Hoff equation and experimental solubility, including Gibbs energy, entropy and enthalpy. The result confirms that the dissolution process in all solvents is always endothermic and entropy driven.

Study of thrmodynamic values in different temperature from partition coefficient for some organic acids immiscible di-solvents mixtures

In the present work the partition co-efficient was studied for some organic aromatic acids quinoline-2- carboxyic acid ,salicylic acid ,aliphatic acid and succinic acid Oxalic acid in different mixtures solvents not mixing diethyl ether + water,chloroform + water and carbontetrachloridde +water at differet temperature vang from(293-318)k. Also the Oxalic properties ,gibbs free energy change ΔG,otherwise enthalpy changee ΔH and entropy change ΔS of partition co-efficient kp have been Oxalic for the dependence of the equilibrium constant(k) to temperature vant Hoff equation,over the temperature rang (293-318)k. The work to show the effects of The work hydrogen on the distribution processes .The results show also the effects of temperature and the number of acidity one acid or diacidic .The thermodynamic values indicated that the distribution processes were spontaneous and endothermic these processes increasing in entropy depending upon spontaneous hydrogen bonding in either spontaneous or strengthened.

Solubility measurement, modeling and Hansen solubility parameters of 8-Chloro-11-(4-methyl-1-piperazinyl)-5H-dibenzo[b,e][1,4]diazepine in four binary solvents

Mole-fraction solubility of 8-Chloro-11-(4-methyl-1-piperazinyl)-5H-dibenzo[b,e][1,4]diazepine (Clozapine, CLZ) in four binary-solvents (tetrahydrofuran (THF), chloroform, 1,2-dichloroethane (EDC) and acetone)-toluene at varied temperatures (from 293.15 K to 323.15 K at 5 K intervals) was experimentally determined by a classic gravimetric method under an atmosphere pressure of 0.101 MPa. The solubility of CLZ in all the selected binary-solvents exhibited a positive relation with temperature. In binary solvents of (THF-toluene, chloroform-toluene or EDC-toluene), the solubility of CLZ had a positive relationship with the mass fraction of co-solvents, while in acetone-toluene system with the rising mass fraction of acetone, the solubility of CLZ initially increased, arrived the highest solubility value at a mass fraction of acetone being 0.5003, and then followed by a decrease. At the same temperature and mass fraction of anti-solvent, the general solubility order of CLZ in binary solvents was THF-toluene > chloroform-toluene > EDC-toluene. In addition, the Hansen solubility parameters (HSPs) and solvents polarity were applied to explore the solubility behavior of CLZ. Four thermodynamic models including Wilson, NRTL, UNIQUAC and three-Suffix Margules were employed to correlate the experimental solubility, which indicated that the NRTL model has the best correlation with the measured solubility data of CLZ according to deviation between the experimental data and the fitting values. Furthermore, the solution thermodynamic properties (ΔdisGo, ΔdisHo and ΔdisSo) of CLZ in the selected four binary-solvents were calculated by van’t Hoff equation, and the positive values of ΔdisHo and ΔdisSo indicated that the dissolution process of CLZ in the measured binary-solvents was endothermic and entropy-driven. The experimental solubility and correlation models in this work can be used as essential data and thermodynamic models in the process development, control and optimization for the industrial dilution crystallization of CLZ.

Solubility of coumarin in (ethanol + water) mixtures: Determination, correlation, thermodynamics and preferential solvation

Equilibrium mole fraction solubility of coumarin in nine aqueous-ethanolic mixtures, as well as in neat water and neat ethanol, was determined at seven temperatures from (293.15 to 323.15) K. Coumarin solubility in was adequately correlated with several well-known correlation models with the mean percentage deviations of 5.1–10.8%. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) for the dissolution, mixing and solvation processes were computed using the van’t Hoff and Gibbs equations. The enthalpy-entropy relationship for coumarin was non-linear in the plot of enthalpy vs. Gibbs energy of dissolution with negative slope from neat water to the mixture of w1 = 0.10 but positive from this mixture to neat ethanol. Accordingly, in the first case the coumarin transfer from neat water to the mixture of w1 = 0.10 is entropy-driven, which could be attributed to water molecules release originally bounded as “icebergs” around the non-polar groups of this drug. Otherwise, in mixtures of w1 ≥ 0.10 the driving mechanism for the transfer of coumarin from the more polar solvent systems to those less polar is the enthalpy, probably owing the better drug solvation. Moreover, by means of the inverse Kirkwood-Buff integrals is observed that apparently coumarin is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in mixtures of 0.23 < x1 < 1.00.

Solubility of trans-resveratrol in {ethanol (1) + water (2)} mixtures revisited: Correlation, dissolution thermodynamics and preferential solvation

ABSTRACT Reported equilibrium mole fraction solubility values of trans-resveratrol in some aqueous-ethanolic mixtures in the temperature interval from (273.2 to 323.2) K were correlated by means of some cosolvency models, like multi-linear models of Jouyban-Acree and Jouyban-Acree-van’t Hoff and non-linear models of the modified Wilson and Buchowski-Ksiazczak. Apparent thermodynamic functions of the dissolution processes were computed using the van’t Hoff and Gibbs equations. Gibbs energy and enthalpy were positive in all cases, while negative and positive entropies were observed. The plot of enthalpy vs. Gibbs energy of dissolution was non-linear with negative slopes in the region of 0.00 ≤ x 1 ≤ 0.60 but positive slope in the region of 0.60 ≤ x 1 ≤ 0.90. Further, by means of the inverse Kirkwood-Buff integrals is observed that trans-resveratrol is preferentially solvated by water in water-rich mixtures but preferentially solvated by ethanol in the composition interval of 0.24 < x 1 < 1.00.

Solid-liquid equilibrium and thermodynamic analysis of elastically bendable crystal celecoxib in thirteen pure solvents based on experiments and molecular simulation

Celecoxib, which is the first elastically bendable single-component pharmaceutical crystal and a new generation of nonsteroidal anti-inflammatory drugs (NSAID) was chosen to investigate its dissolution behavior in thirteen pure solvents by experiments (gravimetric method) and theoretical analysis (including molecular stacking pattern diagram, Hirshfeld surface (HS) analysis, radial distribution function (RDF), and interaction energy). It was found that ester solvents have a better advantage in terms of solubility than alcoholic solvents and acetonitrile, in which ethyl acetate exhibits the best dissolving capacity for celecoxib while isobutanol possesses the smallest solubility. Furthermore, the results of RDF analysis indicate that there is strong hydrogen bond interaction between CXB and measured solvents. The calculation results of interaction energy revealed ethyl acetate has the highest interaction energy with CXB, which is correlated to the best dissolution capacity for CXB. Finally, the measured solubility data were correlated with the modified Apelblat equation, van't Hoff equation, and λh model. All the values of ARD% are lower than 5, indicating that the correlated data are in good agreement with the experimental solubility. The solubility data can offer a productive guide to the practical application areas of elastically bendable single-component pharmaceutical crystal.

Thermodynamic properties study of dissolution of 2-hydroxbenzoic acid in binary solvent (ethanol+ water) at various temperatures11

The dissolution of 2-hydroxbenzoic acid in binary solvent (ethanol+water) mixed with various ethanol concentrations was experimentally tested at temperatures from (293 to 313) K under atmospheric pressure by the equilibrium process. As the temperature rose, the degradation of 2-hydroxbenzoic acid in all ethanol concentrations rose. Tower thermodynamic models like the van't Hoff equation, modified Apelblate equation, were correlated with the dissolution results. The measured dissolution with the modified Apelblate equation was found to provide good agreement with experimental values for the behaviors of 2-hydroxbenzoic acid dissolution. On the basis of the van't Hoff study, the thermodynamic properties of the standard dissolution enthalpy ∆H, standard entropy ∆S, and the standard Gibbs free energy ∆G were evaluated. The values of free energy ∆G and enthalpy ∆H were increased as the percentage of ethanol and temperature increased while the values of entropy ∆S were decreased at the same values. The Nonlinear variation of ∆G, ∆H, and ∆S with mole % indicate there is specific solvation occurring in a water-ethanol mixture Discovered iso-kinetic temperature. 268.7 (less than 300) means that there is a weak interaction between solvent and solvent, or there is a slow shift in the solvent or reactant structure, or both.

Solubility of sildenafil citrate in 1-propanol + water mixtures at different temperatures

Solubility profile for sildenafil citrate in the non-aqueous mixtures of 1-propanol and water is measured using a shake-flask method at different temperatures of 293.2 K, 298.2 K, 303.2 K, 308.2 K and 313.2 K and correlated employing some well-known cosolvency models (e.g. the CNIBS/Redlich-Kister, the Jouyban-Acree, the Jouyban-Acree-van’t Hoff, the modified Wilson and λh equation models) and the accuracy of the models is checked by the calculation of the mean relative deviations. The density values of sildenafil citrate saturated solutions are also investigated and represented by the Jouyban-Acree model. In another effort, to obtain apparent thermodynamic parameters of sildenafil citrate dissolution process, including ΔHo, ΔSo, and ΔGo, the Gibbs and van’t Hoff equations are applied.

PREPARATION AND CHARACTERIZATION OF ACTIVATED CARBON FROM OIL-PALM FIBER AND ITS EVALUATION FOR METHYLENE BLUE ADSORPTION

A new type of activated carbon was produced from oil-palm fiber using steam activation. Scanning electron microscopy (SEM) was performed on the surface of oil-palm-fiber activated carbon (OPF-AC). The spectra of OPF-AC was investigated with Fourier-transform infrared (FTIR) spectroscopy. The effects of the temperature, adsorbent dose, adsorption time and pH on the adsorption properties of methylene blue on OPF-AC were discussed. The Langmuir adsorption model and Freundlich adsorption model were used to find the adsorption equilibrium isotherm. Adsorption kinetics were employed to explain the adsorption process and predict the adsorption efficiency. The Van’t Hoff equation was used to assess the impact exerted by the adsorption temperature on the adsorbing process. According to the results, the data of the adsorption equilibrium of OPF-AC fit well the Langmuir adsorption model and the kinetics data can be gathered into a pseudo-second-order kinetic model. The adsorption behavior of methylene blue on OPF-AC was endothermic and spontaneous. The total pore volume and BET surface area of OPF-AC reached 0.7809 cm3/g and 1018.84 m2/g, respectively. The maximum adsorption capacity of OPF-AC was 862.07 mg/g at 323 K. Accordingly, the gratifying adsorption of OPF-AC endows it with a promising prospect in the application field of agricultural adsorbents.

Thermodynamic Modeling of Phosphorus Recovery from Wastewater for Process Optimization

Although the estimated global phosphorus (P) resources could last 230 years, economically extractable phosphate rock reserves may only last approximately 60 years [1]. Alternative P sources are increasingly valuable as the demand for P fertilizer continues to rise along with global population and food scarcity. P recovery from wastewater (WW) is often achieved via solid precipitation, which can be promoted using chemical and/or electrochemical systems to create conditions that favor the precipitation of solids containing P. Struvite (NH4MgPO4:6H2O), also known as magnesium ammonium phosphate (MAP), is one such solid that is favored under conditions observed in WW from concentrated animal feeding operations (CAFOs). Precipitation of struvite is favored at high pH values, at low concentrations of calcium, and when the Mg:NH4:PO4 molar ratio is near 1:1:1 [2]. Temperature effects on struvite precipitation have not been explored extensively, but precipitation is theoretically favored at lower temperatures [3].The purpose of this study is to more accurately predict solid precipitates in CAFO WW P recovery systems using the chemical equilibrium modeling computer program, PHREEQC, and a novel thermodynamic database. The novel thermodynamic database includes empirically-derived relationships between temperature and equilibrium constants for reactions that are of interest to CAFO WW P recovery systems (i.e. reactions involving species that affect the likelihood of precipitation for P-containing solids). Therefore, the novel database improves the predictive accuracy of solution simulations because PHREEQC employs the Van’t Hoff equation by default, which produces a linear relationship and consequently inaccurate equilibrium constants at temperatures not near 25ºC. In this study, results produced using the novel thermodynamic database are also compared to results produced using a database automatically generated by SupPHREEQC, a recently developed software utility that prints thermodynamic databases in PHREEQC-friendly formats by extracting data from the high-quality database, SUPCRTBL [4].This study also involves an in-depth literature review of kinetic limitations implicit in CAFO WW treatment systems, which affect the likelihood of precipitation of certain solid species and overall P recovery rates. Based on the review, solids deemed unlikely to precipitate are excluded from the modelling simulations. Using the batch reaction capabilities of PHREEQC, P recovery is predicted based on four separate variables: temperature, pH, Ca:Mg ratio, and N:P ratio. The batch reaction functionality provides more meaningful data compared to the saturation index, which is often cited as a proxy for precipitation likelihood but does not consider the competition for dissolved ions posed by other solids. Based on existing water quality data from different WW sources, the thermodynamic model will be used to identify the most promising sources and conditions for P recovery.

Measurement and comprehensive analysis of the solubility of abacavir in twelve pure solvents

The solubility of abacavir in twelve pure solvents (methanol, ethanol, n-propanol, i-propanol, n-butanol, 2-butanol, i-butanol, n-pentanol, water, methyl acetate, ethyl acetate and acetone) was measured by high-performance liquid chromatography (HPLC) at the temperature range of (278.15 to 323.15) K under 101.1 kPa. In the temperature range studied, the solubility of abacavir in selected solvents increased with the rising temperature and the solubility sequence of abacavir at 298.15 K was n-pentanol > n-propanol > 2-butanol > n-butanol > i-butanol > methanol > ethanol > i-propanol > acetone > methyl acetate > ethyl acetate > water. To explain the dissolution behavior of abacavir, the molecular electrostatic potential (MEP) and solvation free energy of abacavir were analyzed by density functional theory (DFT), while the Hansen solubility parameters and KAT-LSER model were introduced to analyze the molecular similarity and the solvent effect, respectively. In addition, three semi-empirical models (modified Apelblat equation, van't Hoff equation and λh equation) and three local composition models (Wilson equation, NRTL equation and UNIQUAC equation) were used to correlate the experimental solubility data of abacavir, and four indicators of relative deviation (RD), average relative deviation (ARD), root-mean-square deviation (RMSD) and coefficient of determination (R2) were introduced to evaluate the correlated data. The results showed that the modified Apelblat equation had the highest accuracy among the semi-empirical models; the NRTL equation was the most representative among the local composition models and had the best goodness-of-fit among all the solubility models. Furthermore, the mixing thermodynamic properties (ΔmixG, ΔmixH and ΔmixS) estimated by NRTL equation indicated that the mixing process of abacavir in selected solvents was spontaneous, exothermic and driven by enthalpy.

Solubility study of ketoconazole in propylene glycol and ethanol mixtures at different temperatures: A laser monitoring method

The solubility of ketoconazole in the mixtures of propylene glycol and ethanol is measured by a laser monitoring technique in the temperature range of 293.2–313.2 K. The generated solubility data are fitted to some linear and non-linear cosolvency models and the accuracy of each model is investigated by calculating the mean relative deviations (MRD%) for the back-calculated data. The apparent thermodynamic parameters of ketoconazole dissolution are also computed according to the van’t Hoff and Gibbs equations.

Physicochemical profile of new antifungal compound: pH-dependent solubility, distribution, permeability and ionization assay

Novel potential antifungal compound of 1,2,4-triazole class − 3,3‘-(piperazine-1,4-diyl)bis(2-(2,4-difluorophenyl)-1-(1H-1,2,4-triazol-1-yl)propan-2-ol) (S-119) - has been synthesized and characterized. Solubility in buffer solutions (pH 2.0 and 7.4), 1-octanol, n-hexane, and ethanol was measured by the isothermal saturation method in the temperature range (293.15–313.15 K). The following order of the solubility was revealed: ethanol > buffer pH 2.0 > 1-octanol > buffer pH 7.4 > n-hexane. The solubility was correlated by the Van’t Hoff and Apelblat equations. The Hansen solubility parameters were applied to solubility evaluation and demonstrated the consistency with the experimental data. The thermodynamic parameters of solubility and transfer processes were calculated and discussed in view of solute–solvent interactions. The temperature dependences of the distribution coefficients of S-119 in 1-octanol/buffer and n-hexane/buffer (pH 2.0 and 7.4) two-phase systems were obtained and considered from the thermodynamic point. The ΔlogD parameter determined from the distribution experiment clearly demonstrated the preference of lipophilic delivery pathways for S-119 in the biologic media and unfavorable transition to the non-polar regions. Membrane permeability coefficient of S-119 was determined and evaluated with the assistance of the respective parameter for the structurally related drug fluconazole.

Solubility measurement and thermodynamic modeling of caffeine in N-methyl-2-pyrrolidone + isopropanol mixtures at different temperatures

The solubility knowledge of pharmaceutical compounds in pure solvents and solvent mixtures has a critical role in formulation, separation and purification in the pharmaceutical and chemical industries. In the article ahead, the solid–liquid equilibria measurements for solubility of caffeine in the non-aqueous binary mixtures of N-methyl-2-pyrrolidone (NMP) and isopropanol at different temperatures and atmospheric pressure is measured and the acquired data are fitted to some linear and non-linear cosolvency models including the van’t Hoff, the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K), Jouyban-Acree, Jouyban-Acree-van’t Hoff, and the modified Wilson models. The determined density data of caffeine saturated solutions as another physico-chemical property are also correlated with the Jouyban-Acree model and the results are discussed in detail. The mean relative deviations (MRD%) of the back-calculated solubility data aiming to study the accuracy of the applied models are computed. Moreover, the apparent thermodynamic properties of caffeine dissolution process are also calculated by using van’t Hoff and Gibbs equations.

Hot Deformation Behavior and Hot Rolling Properties of a Nano-Y2O3 Addition Near-α Titanium Alloy

The hot deformation behavior and hot rolling based on the hot processing map of a nano-Y2O3 addition near-α titanium alloy were investigated. The isothermal compression tests were conducted at various deformation temperatures (950⁠–1070 °C) and strain rates (0.001–1 s−1), up to a true strain of 1.2. The flow stress was strongly dependent on deformation temperature and strain rate, decreasing with increased temperature and decreased strain rate. The average activation energy was 657.8 kJ/mol and 405.9 kJ/mol in (α + β) and β region, respectively. The high activation energy and peak stress were contributed to the Y2O3 particles and refractory elements comparing with other alloys and composites. The deformation mechanisms in the (α + β) region were dynamic recovery and spheroidization of α phase, while the β phase field was mainly controlled by the dynamic recrystallization and dynamic recovery of β grains. Moreover, the constitutive equation based on Norton–Hoff equation and hot processing map were also obtained. Through the optimal processing window determined by the hot processing map at true strains of 0.2, 0.4 and 0.6, the alloy sheet with multi-pass hot rolling (1050 °C/0.03–1 s−1) was received directly from the as-cast alloy. The ultimate tensile strength and yield strength of the alloy sheet were 1168 MPa and 1091 MPa at room temperature, and 642 MPa and 535 MPa at 650 °C, respectively, which performs some advantages in current research.

Mechanism and microstructural evolution of TiCrVFe hydrogen storage alloys upon de-/hydrogenation

TiCrVFe alloys have attracted significant attention because of their fast de-/hydrogenation rates and high reversible hydrogen capacities at moderate temperatures, but few studies have reported their de-/hydrogenation kinetics and thermodynamics. In this work, TiCrVFe alloys with different Ti/Cr ratios were prepared by arc melting, and their microstructural evolution and de-/hydrogenation mechanisms were investigated. XRD analysis confirmed that the crystal structure of TiCrVFe alloy transformed from BCC to FCC after hydrogenation, with lattice constants increasing from 3.0327 Å to 4.2714 Å. Combined the XRD with SEM-EDS analysis of the alloy after de-/hydrogenation tests, the hydrogenation expansion destroyed partial crystal lattice of the alloy and resulted in the generation of numerous defects and dislocations. This explains the slight fading of the cyclic capacity after several cycles. It was found that the hydrogen absorption kinetics of TiCrVFe alloys were controlled by 3D diffusion mechanisms, with an activation energy of −18.41 kJ/mol in the temperature range of 3–65 °C. The enthalpy change of the alloy (Ti27Cr27V40Fe6) was determined to be 45.68 kJ/mol upon hydrogenation and 51.33 kJ/mol upon dehydrogenation by the PCT curves and Van’t Hoff equation. The enthalpy change of the Ti27Cr27V40Fe6 hydride upon dehydrogenation was consistent with the heat change in its DSC result. The results obtained in this work are useful for the application of TiCrVFe alloys as H2 storage materials in fuel cell vehicles or devices.

Solubility Determination and Thermodynamic Correlation of 3-Amino-2-methylbenzoic Acid in 12 Monosolvents from 288.15 to 328.15 K

A gravimetric method is adopted to measure the solid–liquid equilibrium of 3-amino-2-methylbenzoic acid in different solvents, including methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol, isobutyl alcohol, 2-butanol, methyl acetate, ethyl acetate, propyl acetate, water, and acetonitrile. Moreover, the experiment is carried out at atmospheric pressure, and the temperature range is from 288.15 to 328.15 K. The solid–liquid equilibrium of 3-amino-2-methylbenzoic acid in all used solvents increases with increasing temperature. In alcohol solvents, except for isopropyl alcohol and 2-butanol, the solubility of 3-amino-2-methylbenzoic acid is positively related to the polarity of the solvent, which follows the “like dissolves like” rule. Because isopropyl alcohol and 2-butanol possess a high hydrogen bond acceptor propensity, this leads to a different solubility behavior. In nonalcohol solvents, the solid–liquid equilibrium of 3-amino-2-methylbenzoic acid also follows the “like dissolves like” rule. Among all 12 solvents, the solid–liquid equilibria of 3-amino-2-methylbenzoic acid in water and acetonitrile are lower than those in alcohols and esters. In addition, the solid–liquid equilibrium data of 3-amino-2-methylbenzoic acid were related by the modified Apelblat equation, van’t Hoff equation, and λh equation. Furthermore, all relevant results show consistency with the solid–liquid equilibrium data of 3-amino-2-methylbenzoic acid.

Solubility Measurement and Data Correlation of 4-Chlorophenoxyacetic Acid in 13 Monosolvents at Temperatures from 283.15 to 328.15 K

The solubility of 4-chlorophenoxyacetic acid (4-CPA) in 13 monosolvents including ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, acetonitrile, and 1,4-dioxane was measured by a gravimetric method from 283.15 to 328.15 K at an atmospheric pressure of 0.1013 MPa. The solubility of 4-CPA increased with temperature and followed the order 1,4-dioxane > alcohols > esters > acetonitrile at all experimental temperatures. The solvent effects, especially solvent polarity, hydrogen bond donor propensity, and hydrogen bond acceptor propensity, were used to analyze the solubility of 4-CPA in different solvents. The solubility basically follows the rule “like dissolves like” and has a higher value in solvents with strong hydrogen bond donor propensity and hydrogen bond acceptor propensity. Besides, the modified Apelblat equation, λh equation, and van’t Hoff equation were applied to correlate the measured solubility data. The average relative deviation (ARD) values showed that the correlation results of the three models agree well with the experimental data.

Solubility determination and thermodynamic modeling of bis-2-hydroxyethyl terephthalate (BHET) in different solvents

Studies on the degradation process of waste polyethylene terephthalate (PET) have become increasingly mature, but there are relatively few studies on the separation of degradation products. The products contain many components and the separation of which is difficult. Therefore, the study on phase equilibrium thermodynamics of bis-2-hydroxyethyl terephthalate (BHET) is of great theoretical significance and practical value to provide basic data for the BHET crystallization separation. In this work, the degraded products were purified and characterized. The solubility of BHET in methanol, ethanol, ethylene glycol, water and the mixture of ethylene glycol + water were determined by static method. The experimental results were correlated with different models, such as ideal solution (IS) model, λh equation, Apelblat equation and NRTL model. Based on the van't Hoff equation, the mixing Gibbs energy, enthalpy and entropy were calculated. From this work, the basic data which can be used to guide the crystallization process of BHET were obtained, including solubility data, correlation model and thermodynamic properties.

Solubility study of mesalazine in the aqueous mixtures of a deep-eutectic solvent at different temperatures

The solubility and solution thermodynamic properties of mesalazine in the binary mixtures of a deep eutectic solvent (DES) and water are determined by a shake-flask method followed by spectrophotometry method in the temperature range of 293.2–313.2 K. The obtained solubility data are correlated using some linear cosolvency models including the van’t Hoff equation, the Apelblat, Jouyban-Acree, Jouyban-Acree-van’t Hoff models. The accuracy of each used model is investigated by calculation of the mean relative deviations of the back-calculated solubility data. The apparent thermodynamic properties of mesalazine dissolution in the investigated mixtures are also computed based on the van’t Hoff and Gibbs equations.