Hoff Equation Research Articles

Experimental Determination and Computational Prediction of Dehydroabietic Acid Solubility in (-)-α-Pinene + (-)-β-Caryophyllene + P-Cymene System.

The solubility of dehydroabietic acid in (−)-α-pinene, p-cymene, (−)-β-caryophyllene, (−)-α-pinene + p-cymene, (−)-β-caryophyllene + p-cymene and (−)-α-pinene + (−)-β-caryophyllene were determined using the laser monitoring method at atmospheric pressure. The solubility of dehydroabietic acid was positively correlated with temperature from 295.15 to 339.46 K. (−)-α-pinene, p-cymene, and (−)-β-caryophyllene were found to be suitable for the solubilization of dehydroabietic acid. In addition, the non-random two liquid (NRTL), universal quasi-chemical (UNIQUAC), modified Apelblat, modified Wilson, modified Wilson–van’t Hoff, and λh models were applied to correlate the determined solubility data. The modified Apelblat model gave the minor deviation for dehydroabietic acid in monosolvents, while the λh equation showed the best result in the binary solvents. A comparative analysis of compatibility between solutes and solvents was carried out using Hansen solubility parameters. The thermodynamic functions of ΔsolH0, ΔsolS0, ΔsolG0 were calculated according to the van’t Hoff equation, indicating that the dissolution was an entropy-driven heat absorption process. The Conductor-like Screening Model for Real Solvents (COSMO-RS) combined with an experimental value was applied to predict the reasonable solubility data of dehydroabietic acid in the selected solvents systems. The interaction energy of the dehydroabietic acid with the solvent was analyzed by COSMO-RS.

Equilibrium solubility of 6-methylcoumarin in some (ethanol + water) mixtures: determination, correlation, thermodynamics and preferential solvation

ABSTRACT The solubility of 6-methylcoumarin in water, ethanol and nine aqueous ethanol mixtures was determined from 293.15 to 323.15 K. 6-Methylcoumarin solubility expressed in mole fraction was correlated with some well-known correlation/prediction models. Gibbs energy, enthalpy and entropy, for dissolution and mixing processes, were computed using van’t Hoff and Gibbs equations. The plot of enthalpy vs. Gibbs energy of dissolution exhibited negative slopes from water to w 1 = 0.20 and from w 1 = 0.90 to ethanol but positive slopes in the interval 0.20 < w 1 < 0.90. 6-Methylcoumarin transfer from water to w 1 = 0.20 is entropy-driven that could be attributed to water molecules releasing originally bounded as ‘icebergs’ around the drug-non-polar groups. In mixtures of 0.20 < w 1 < 0.90, enthalpy-driving mechanism for drug transfer from more-polar to less-polar systems is observed, probably owing to better solvation by ethanol. Inverse Kirkwood–Buff integrals show that 6-methylcoumarin is preferentially solvated by water in water-rich mixtures but preferentially solvated by ethanol in 0.24 < x 1 < 1.00.

Calculating osmotic pressure of liquid mixtures by association theory for sustainable separating of solvents by membrane processes

Recent years, the separation of organic liquid mixtures achieved by organic solvent nanofiltration (OSN), organic solvent reverse osmosis (OSRO), and organic solvent forward osmosis (OSFO) has gained a great momentum. In the methods, it is of particular importance to know the osmotic pressure of liquid mixtures for the correct process design. Although the Van’t Hoff law is frequently employed to estimate the osmotic pressure of such mixtures, unprecedented serious errors might be added to the results. In this study, the osmotic pressure of numerous binary liquid mixtures is predicted using the original definition of osmotic pressure along with the cubic plus association (CPA) equation of state (EoS) and the Van’t Hoff equation at various temperatures and compositions. CPA EoS considers hydrogen bonding effects in associating compounds (those with hydrogen bonds such as water and alcohols). The obtained results reveal that unlike the Van’t Hoff equation (the average deviation = 19.95 bar), the original definition of osmotic pressure with the aid of CPA EoS (the average deviation = 3.86 bar) can properly predict the osmotic pressure of the studied mixtures. Our findings are beneficial for various techniques utilized in the separation of organic liquid mixtures.

Solubility and thermodynamic properties of N-phenylanthranilic acid in Water + Methanol/Ethanol/tert-butanol binary solvents from 283.15 K to 323.15 K

The solubility of N-phenylanthranilic acid in water + tert-butanol/ethanol/methanol was determined by gravimetric method in the temperature range of (283.15 ∼ 323.15) K at atmospheric pressure. Within this temperature range, the solubility increased with increase in the temperature. The descending order of the mole fraction solubility in binary solvents was as follow: water + tert-butanol > water + ethanol > water + methanol. The solubility was correlated by the Jouyban − Acree model. The van't Hoff equation was employed to analyze the thermodynamic properties of dissolution process including the Gibbs energy, enthalpy and entropy. The knowledge of solubility and thermodynamic properties is essential for design of the crystallization and purification of N-phenylanthranilic acid.

Thermodynamic data measurement and analysis of organoaluminum supported by β-diketimine ligand in several solvents

Organoaluminum compounds are supported by β-diketimine ligands were widely used in organic synthesis, homogeneous catalysis and other fields due to their unique structure and properties. In this article, the static equilibrium method was used to determine the solubility of LAlMe2 (L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) in four pure solvents (n-hexane, toluene, tetrahydrofuran, dichloromethane) and two binary solvent systems (n-hexane + toluene, n-hexane + dichloromethane). All operations were performed under Schlenk technology or a glove box under nitrogen atmosphere, and measurement temperature was 263.15 K to 308.15 K. The experimental results showed that the solubility of LAlMe2 gradually increased with the elevated of temperature and presents an increasing trend with the increase of the mass fraction of co-solvent in the mixed solvent. Hansen solubility parameter explained the dissolution behavior of LAlMe2. Six thermodynamic models were used to correlate the solubility data. The results showed that the Apelblat model and the Yaws model have the most extensive applicability in both pure solvent and binary solvent systems. In addition, thermodynamic parameters, such as ΔsolHo, ΔsolSo and ΔsolGo were calculated by Gibbs function and Van’t Hoff equation and the enthalpy- entropy compensation in the dissolution process was analyzed. It was concluded that dissolution is an endothermic process driven by entropy and ΔsolHo is the main factor affecting ΔsolGo.

A structure-property model for the prediction of pKa values of different amines in the CO2 capture process of concern to the prediction of thermodynamic properties

In this study, Quantitative Structure-Property Relationship (QSPR) method has been applied on a dataset including the pKa values of 21 different structures (20 amines and ammonia) at four temperatures in the post-combustion-capture process using QSARINS. QSPR models have been accomplished in two situations, called fixed and unfixed temperatures. In the fixed temperatures, four predictive models with one descriptor have been separately developed at each temperature. Besides, thermodynamic properties have been calculated by the van’t Hoff equation using predicted pKa values. In the unfixed temperatures, two general models were developed which take into account the effects of molecular structure and temperature, simultaneously. The predicted pKa values and calculated Gibbs free energy have a good consistency with related values in the literature. The reliability of each developed model has been examined using external assessments. The values of some statistical parameters such as R2 = 0.89 and AARD% = 2.68 verify the prediction capability of models.

Hydroquinone Solubility in Pure and Binary Solvent Mixture at Various Temperatures with FTIR

Gravimetric method is used to measured hydroquinone solubility in water, ethanol and in water+ethanol binary mixtures at temperatures (293.15, 295.15, 298.15, 300.15, 303.15, 305.15, 308.15, 310.15 and 313.15)K. Mole fractions solubility of hydroquinone are correlated with temperature by using the Apelblat equation. The combined nearly ideal binary solvent (NIBS)-Redlich-Kister equation is used to fit experimental hydroquinone solubility data in mixed solvents at constant temperature. ΔH0soln, ΔG0soln, and ΔS0soln are thermodynamic functions of hydroquinone in different solvents, obtained from the modified van’t Hoff equation. FTIR study is done for some hydroquinone solution.

Solvent and Counteranion Assisted Dynamic Self-Assembly of Molecular Triangles and Tetrahedral Cages.

Self-assembly of naked PdII ions separately with newly designed bis(3-pyridyl)benzothiadiazole (L1) and bis(3-pyridyl)thiazolo[5,4-d]thiazole (L2) donors separately, under varying experimental conditions, yielded Pd4L8 (L= L1 or L2) tetrahedral cages and their homologous Pd3L6 (L= L1 or L2) double-walled triangular macrocycles. The resulting assemblies exhibited solvent, temperature, and counteranion induced dynamic equilibrium. Treatment of L1 with Pd(BF4)2 in acetonitrile (ACN) resulted in selective formation of a tetrahedral cage [Pd4(L1)8](BF4)8 (1a), which is in dynamic equilibrium with its homologue triangle [Pd3(L1)6](BF4)6 (2a) in dimethyl sulfoxide (DMSO). On the other hand, similar self-assembly using L2 instead of L1 yielded an equilibrium mixture of tetrahedral cage [Pd4(L2)8](BF4)8 (3a) and triangle [Pd3(L2)6](BF4)6 (4a) forms in both ACN and DMSO. The assembles were characterized by multinuclear NMR and ESI-MS while the structure of the tetrahedral cage (1a) was determined by single crystal X-ray diffraction. Existence of a dynamic equilibrium between the assemblies in solution has been investigated via variable temperature 1H NMR. The equilibrium constant K = ([Pd4L8]3/[Pd3L6]4) was calculated at each experimental temperature and fitted with the Van't Hoff equation to determine the standard enthalpy (ΔH°) and entropy (ΔS°) associated with the interconversion of the double-walled triangle to tetrahedral cage. The thermodynamic feasibility of structural interconversion was analyzed from the change in ΔG°, which suggests favorable conversion of Pd3L6 triangle to Pd4L8 cage at elevated temperature for L1 in DMSO and L2 in ACN. Interestingly, similar self-assembly reactions of L1 and L2 with Pd(NO3)2 instead of Pd(BF4)2 resulted in selective formation of a tetrahedral cage [Pd4(L1)8](NO3)8 (1b) and double-walled triangle [Pd3(L2)6](NO3)6 (4b), respectively.

Multiobjective Evaluation of Amine-Based Absorbents for SO2 Capture Process Using the pK a Mathematical Model.

The screening of high-efficiency and low-energy consumption absorbents is critical for capturing SO2. In this study, absorbents with better performance are screened based on mechanism, model, calculation, verification, and analysis methods. The acidity coefficient (pKa) values of ethylenediamine (EDA), piperazine (PZ), 1-(2-hydroxyethyl)piperazine (HEP), 1,4-bis(2-hydroxyethyl)piperazine (DIHEP), and 1-(2-hydroxyethyl)-4-(2-hydroxypropyl)piperazine (HEHPP) are calculated by quantum chemical methods. A mathematical model of the SO2 cyclic absorption capacity per amine (αc) in the amine-based SO2 capture process is built based on the electroneutrality of the solution. Another model of desorption reaction heat (Qdes) is also built based on the van’t Hoff equation. Correspondingly, αc and Qdes of the above five diamines are calculated and verified with the experimental data. The results show that αc of the diamine changes with the increase in the pKa value, and the increase in the pKa value directly leads to changes in Qdes. The order of αc of the above five diamines is EDA > PZ > HEHPP > HEP > DIHEP, and the order of Qdes is EDA > PZ > HEHPP > DIHEP > HEP. The multiobjective analysis between αc and Qdes suggests that it is not advisable to simply pursue a higher αc while ignoring Qdes. The compound quaternary system absorbent has a wider range of αc than the single ternary absorbent, which is the direction of absorbent development. This study is expected to strengthen absorbent screening for the amine-based SO2 capture process from flue gas.

Equilibrium solubility of trans-resveratrol in {acetone (1) + water (2)} mixtures: Correlation, dissolution thermodynamics and preferential solvation

ABSTRACT Reported mole fraction solubilities of trans-resveratrol in aqueous mixtures of acetone in the temperature interval from (273.2 to 313.2) 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 CNIBS/R-K model. Apparent thermodynamic quantities of the dissolution processes were computed using the van’t Hoff and Gibbs equations. Gibbs energies and enthalpies 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 ≤ 0.70 but positive slopes in the region of 0.70 ≤ x 1 ≤ 1.00. Further, by means of the inverse Kirkwood-Buff integrals is observed that trans-resveratrol is preferentially solvated by water in water-rich and acetone-rich mixtures but preferentially solvated by acetone in the composition interval of 0.21 < x 1 < 0.77.

Synthesis, characterization and investigating the binding mechanism of novel coumarin derivatives with human serum albumin: Spectroscopic and computational approach

Two 4-hydroxycoumarin derivatives: (E)-3-(1-((4‑hydroxy-3-methoxyphenyl)amino) -ethylidene)chromane-2,4‑dione (L1) and (E)-3-(1-((3‑hydroxy-4-methoxyphenyl)-amino)ethylidene) chromane-2,4‑dione (L2), were prepared and structurally characterized by spectroscopic techniques in combination with the B3LYP-D3BJ theoretical method. The interactions between newly synthesized compounds and human serum albumin (HSA) were investigated under physiological conditions at 296,303, and 310 K by fluorescence and absorption spectroscopy, molecular docking, and molecular dynamic simulations. The results of absorption and fluorescence spectral analysis showed that ligands quenched HSA fluorescence through a static process. The corresponding thermodynamic parameters ΔH0, ΔS0, and ΔG0 were calculated according to Van't Hoff's equation. The obtained results indicated that compounds bind spontaneously to HSA mainly by van der Waals's forces and through hydrogen bonds. Ligand-competitive displacement experiments, using known site-specific ligands for HSA's binding sites (I and II) suggest that ligands had a higher affinity for site I (subdomain IIA). The results of the computational analysis follow the experimental data, and the obtained results suggest that the investigated compounds show a good binding affinity according to the HSA receptor, which will be useful for future studies related to rational drug design.

Solubility measurement, thermodynamic modeling, and molecular dynamic simulation of regorafenib in pure and binary solvents

The solubility of regorafenib in six pure solvents (ethanol, acetonitrile, methanol, n-propanol, isopropanol, and acetone) and binary solvent mixtures (acetone + acetonitrile) was determined by the gravimetric method from 278.15 K to 313.15 K. The mole solubility of regorafenib increased monotonously with increased temperature. The solubility data were fitted by four thermodynamic models, namely, the modified Apelblat, λh, non-random two-liquid, and Wilson models. The modified Apelblat model showed the most accurate correlation with solubility data. Molecular dynamics simulation including solvation free energy calculations and radial distribution function were performed to understand the influence mechanism of solute–solvent and solvent–solvent interaction on solubility. The results of solvation free energy calculations well agreed with the solubility order of regorafenib in selected solvents. However, the solvent–solvent interaction had no significant effect on solubility. Moreover, the thermodynamic properties (ΔdisH0,ΔdisS0andΔdisG0) of regorafenib were calculated using the van’t Hoff equation. The positive value of ΔdisH0andΔdisS0 indicated an entropy-driven and endothermic process of dissolution of regorafenib. These findings can serve as a reference for future synthesis process selection, formulation research, and optimization, as well as for understanding the solid–liquid equilibrium of regorafenib and predict its solubility which is of great significance to production.

Solubility, MD simulation, thermodynamic properties and solvent effect of perphenazine (Form I) in eleven neat organic solvents ranged from 278.15 K to 318.15 K

Perphenazine has rather effective in the treatment of mental illness. In this work, the solid-liquid equilibrium data of perphenazine in eleven organic neat solvents were determined by laser dynamic method under the atmospheric pressure and temperature range of 278.15 K ∼ 318.15 K. The selected solvents were n-propanol, n-butyl alcohol, methyl acetate, ethyl acetate, n-propyl acetate, n-amyl acetate, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAC), acetone, 2-methoxyethanol, glycol ether, respectively. From the results, the solubility of perphenazine is all positively correlated with temperature. Separately, we have adopted the KAT-LSER model and molecular dynamics simulation to investigate the influence of solvent effects and solute-solvent interaction on solute solubility. Meanwhile, there were four activity coefficient models being used to correlate the solubility data and Average relative deviation of models are 4.13% (Margules model), 3.94% (NRTL model), 4.49% (NRTL-SAC model) and 3.06% (UNIQUAC model), respectively, all of which do not exceed 5%. It manifests that the four activity coefficient models can fit the experimental values well, in which the UNIQUAC model gives the best regression effect. Moreover, the apparent thermodynamic properties(△solG°, △solH° and △solS°) of perphenazine in various solvents were calculated by Van’t Hoff equation. In accordance with the analysis and calculation of dissolution, the dissolution process is an endothermic entropy-driven process. This research can provide basic data for the crystallization process of perphenazine.

The mass transfer and mechanism of H3PO4 from low concentration HCl-route wet-process phosphoric acid by the mixture of n-butanol and isopropyl ether

• The mixed solvent of nBA and IPE was first used to extract H 3 PO 4 from HCl-route WPA. • The relation of E i, tal and N for all tested components were summarized. • The thermodynamic data of extraction process was calculated. • The mechanism and stage of H 3 PO 4 extraction were analyzed. Solvent extraction of phosphoric acid from wet process phosphoric acid produced by decomposing low grade phosphate with hydrochloric acid was investigated by the mixture of n-butanol (nBA) and isopropyl ether (iPE). The experimental results show that the mixture has good performance on P 2 O 5 extraction and Ca 2+ purification from HCl-route wet-process phosphoric acid. Optimization of extraction process shows that nBA has good performance for H 3 PO 4 separation at the condition of 5:1 O/A phase ratio, 293 K extraction temperature, 9:1 V B /V E ratio and 15 min extraction time. Based on the Van't Hoff equation, the enthalpy changes of P 2 O 5 extraction was calculated to be −16.41 kJ.mol −1 . The results from liquid-liquid mass transfer show three stages can achieved about 90 wt% P 2 O 5 extraction regardless of the countercurrent and cocurrent extraction. And the relation of total extraction percent and cross-flow extraction stages for all tested components were summarized. Moreover, the extraction mechanism between H 3 PO 4 and nBA was discussed by researching the extraction equilibrium under different conditions. The result showed that phosphoric acid was extracted in the form of H 3 PO 4 ·nBA, H 3 PO 4 ·2 nBA and H 3 PO 4 ·3 nBA complexes. Stripping operations using Deionized water as a extractant for phosphoric acid was also investigated at different conditions.

EXTRAÇÃO DE CORANTES TÊXTEIS UTILIZANDO SISTEMAS AQUOSOS BIFÁSICOS COMPOSTOS POR 2-PROPANOL E SAIS DE SULFATO

EXTRACTION OF TEXTILE DYES USING TWO-PHASE AQUEOUS SYSTEMS COMPOSED OF 2-PROPANOL AND SULFATE SALTS. Aqueous Two Phase Systems (ATPS) composed of 2-propanol + inorganic salt (Na2SO4/MgSO4) + water, at different temperatures T = (20, 30, 40 and 50) °C were applied in the partition studies of the textile dyes Yellow, Blue Royal and Red Dianix CC. The thermodynamic parameters of the free transfer energy (ΔGtr), enthalpy (ΔHtr) and entropy (ΔStr), respectively, were determined for dye partitioning, using the Van’t Hoff equation. The values of the partition coefficients of textile dyes Yellow, Royal Blue and Red Dianix CC, ranged from 14.21 to 1610.00, 15.15 to 994.00 and 17.32 to 311.75, respectively; and with dye extraction yields ranging from 93.17 to 99.93; 94.53 to 99.89 and 97.19 to 99.64, respectively. Based on the ΔGtr results, it was verified that the dyes partition process was thermodynamically spontaneous, in all evaluated systems. For the 2-propanol + sodium sulfate ATPS, there was a prevalence of the enthalpic contribution over the entropic contribution (ΔHtr &gt; ΔStr), while for the 2-propanol + magnesium sulfate systems, a greater predominance of the entropic contribution was observed (ΔHtr &lt; ΔStr). The recovery yields (Y) values obtained were above 90% for all systems.

Factors Controlling the Dissolved 137Cs Seasonal Fluctuations in the Abukuma River Under the Influence of the Fukushima Nuclear Power Plant Accident

AbstractThe 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released large amounts of radioactive materials into the environment. River systems play an important role in the terrestrial redistribution of FDNPP‐derived 137Cs in association with water and sediment movement. We examined the seasonal fluctuations in dissolved and particulate 137Cs activity concentrations and clarified the biological and physicochemical factors controlling 137Cs seasonality in the Abukuma River's middle course in the region affected by the FDNPP accident. The results showed seasonal fluctuations in the dissolved 137Cs activity concentration, with an increase in summer and a decrease in winter, although there was no clear seasonal change in the particulate 137Cs activity concentration. Water temperature and K+ concentration dominated the seasonality of the dissolved 137Cs activity concentration. The volumetric activity concentration of the organically bound 137Cs was found to be several orders of magnitude lower than that of the dissolved 137Cs. Therefore, we concluded that the 137Cs in organic matter is not a source of dissolved 137Cs in river water. The study also revealed the temperature dependence of Kd in riverine environments from a Van't Hoff equation. The standard reaction enthalpy of 137Cs in the Abukuma River was calculated to be approximately −19.3 kJ/mol. This was the first study to clearly reveal the mechanisms by which the dissolved 137Cs activity concentration and Kd are influenced by chemical and thermodynamic processes in the middle course of a large river, and it is expected to lead to an improved model of 137Cs dynamics in rivers.

جهد ألإمتزاز لمزيج من ألاطيان ألمنشطة كيميائيا وحراريا لإزالة صبغة ألمثيل ألبرتقالي من مياة ألصرف الصحي

This study examined the adsorption behavior of anionic dye (orange G) from aqueous solution onto the raw and activated a mixture of illite, kaolinite and chlorite clays from area of Zorbatiya (east of Iraq).The chemical treatment involved alkali and acid activation. The alkali activation obtained by treated the raw clay (RC) with 5M NaOH (ACSO) and the acid activation founded by treated it with 0.25M HCl (ACH) and 0.25M H_2 〖SO〗_4 (ACS). The thermal treatment carried out by calcination the produce activated clay at 750oC for acid activation and 105oC for alkali activation. Batch adsorption method was used to study the adsorption of orange G dye onto raw and activated clays. The impact of different factors related to the adsorption process was studied such as: agitation time, clay dosage, solution pH, starting OG dye concentration, temperature and ionic strength. The adsorption process was described by using Langmuir, Freundlich, Temkin and Dubinin-Raduchkevish isotherm models. Thermodynamic functions like change in enthalpy〖∆H〗^°, change in entropy 〖∆S〗^° and change in Gibbs free energy 〖∆G〗^°were estimated based on Vanʼt Hoff equation.

Removal of Reactive Green Dye from Textile Waste Water by Photo Fenton Process: Modeling, Kinetic, and Thermodynamic.

This work investigated the removal of the reactive green (R.G) dye from wastewater using the photo-Fenton process. Batch experiments were carried out to research the role of the Impacts of operating parameters. The dosage of H2O2; dosage Fe+2; pH; temperature, and irradiation time were examined. Maximum decolorization efficiencies green dye were achieved at the [H2O2]=100 ppm; [Fe2+]=20 ppm; pH 3; temperature=56 °C and irradiation time=90 min. This research focuses on modeling, kinetics and thermodynamics of the removal of pollutant (reactive green dye) of water. The results showed that the decolorization kinetic of R.G followed pseudo-first-order reaction kinetic. Also the thermodynamic parameters ∆G˚, ∆H˚ and ∆S˚ were determined using the Van't Hoff equation for the oxidation processes. The changes in Gibbs free energy showed the oxidation process under normal conditions is non-spontaneous.

Solubility of baclofen in some neat and mixed solvents at different temperatures

Knowledge of drug solubility is crucial and there is no available cosolvency database for baclofen, so far. In the current study, the solubility and density values of baclofen in five mono-solvents (i.e. methanol, ethanol, 1-propanol, 2-propanol and propylene glycol) and the binary mixed solvents of propylene glycol and ethanol within the temperature range of (293.2 –313.2) K are measured using shake-flask method followed by spectroscopy method. The generated data are correlated using some cosolvency models (e.g. the van’t Hoff, CNIBS/Redlich-Kister, the Jouyban-Acree, the Jouyban-Acree-van’t Hoff and λh models). The mean relative deviations for back-calculated solubility data were employed to investigate the accuracy of the models. Moreover, the apparent thermodynamic properties of dissolution of baclofen in the binary non-aqueous mixtures of solvents such as Gibbs free energy, entropy and enthalpy were computed using van't Hoff and Gibbs equations.

Solubility of amlodipine besylate in binary mixtures of polyethylene glycol 400 + water at various temperatures: Measurement and modelling

Measuring and evaluating of the solubility of amlodipine besylate (AMB), as a low water soluble antihypertensive drug, is fundamentally important in the pharmaceutical industry. In this work, the solubility of AMB in the binary solvent system of water and polyethylene glycol 400 (PEG 400) was determined by a shake-flask method at the temperatures from 293.2 to 313.2 K. According to the obtained results, the solubility of AMB increases nonlinearly with increasing the mass fraction of PEG 400. The maximum mole fraction solubility of AMB was observed at 313.2 K with a PEG 400 mass fraction of 0.9. The experimental solubility data points were correlated by Jouyban-Acree, Jouyban-Acree-van’t Hoff and CNIBS/R-K as linear models and NRTL, Wilson and UNIQUAC as nonlinear models. Of them CNIBS/R-K and NRTL models performed the best in correlation results. The dissolution and mixing thermodynamic properties such as enthalpy, Gibbs free energy, and entropy were also calculated based on Gibbs and van’t Hoff equations to investigate the solvation behavior of AMB in the aqueous PEG 400 mixtures. The density values of AMB saturated mixtures of the PEG 400 and water at different temperatures were also measured and correlated with the Jouyban-Acree model.