Partial Molar Volumes Research Articles

Solid–Liquid Diffusion Stresses Leading to Voiding

AbstractThis paper discusses cavitation within a two-phase solid–liquid enclosed system due to interdiffusion. This mechanism is discussed within the context of solid–liquid interdiffusion bonding for metal systems and the voids which are caused by this mechanism. A case study composed of liquid (Sn), Ni3Sn4, and (Ni) phases was used. The mechanical tension and bubble volume resulting from the mechanically enclosed system during isothermal solidification at 250 °C were calculated using a fitted 1D growth model coupled with thermodynamics. Thermodynamic energy calculations showed that it becomes favorable for cavitation after 6 seconds for a starting liquid pocket of 5 µm3. The critical pressure for this cavitation was − 0.029 GPa. The volumetric change for the reaction was determined to be − 12.3 vol pct by a partial molar volume balance. While the volumetric change determined by the thermodynamics found − 7.2 vol pct. The likely presence of unwettable inclusions in non-pure liquids would circumvent this cavitation mechanism, even though cavitation conditions are present. Meaning cavitation for these systems can only be expected when the liquid metal purity is sufficient. Lastly, the bubble growth is attributed to a combination of thermodynamic bubble growth and Kirkendall vacancies.

New insight into molecular interactions of surface-active ionic liquid (SAIL) with some biomolecules: Experimental and computational approaches

Understanding the influence of ionic liquids (ILs) on the solubility of biomolecules in aqueous solutions is crucial for designing and optimizing novel biotechnological processes. However, the molecular-level mechanisms underlying this influence remain inconclusive and not fully elucidated. To contribute toward the understanding of molecular interactions between amino acids and ionic liquid in aqueous media, measurements of the densities and speeds of sound for L-serine and glycyl-L-serine in (0.00, 0.005, 0.01, 0.03, and 0.05) mol·kg−1 aqueous solutions of 1-octyl-3-methylimidazolium bromide were conducted at T = (288.15, 298.15, 308.15, and 318.15) K. From experimental data various thermodynamics paramours such as apparent molar volume (Vϕ), the partial molar volume (Vϕ0), standard partial molar volumes of transfer (ΔVϕ0) partial molar isentropic compression (Kϕ,s) and partial molar isentropic compression of transfer (ΔKϕ,S0) have been examined. Along with experiment results, computational tools were also utilized for a deeper understanding of the molecular changes. From density functional theory (DFT), the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were calculated and utilized to obtain molecular descriptors such as ionization energy (I), electron affinity (A), hardness (η), softness (S), chemical potential (μ), and electronegativity (χ). Thermochemical properties, including change in enthalpy (ΔH), and change in Gibbs free energy (ΔG), were predicted. Molecular docking studies were used to analysis the molecular interaction of ionic liquid with I-Motif structure and structural changes.

Hydration behavior of D-calcium pantothenate (vitamin B5) in the presence of sugar-based deep eutectic solvents at different temperatures: experimental and theoretical study

Considerable efforts have been devoted in recent years to enhancing the efficacy medicinal substance, leading to the discovery of innovative drug formulations and delivery techniques. The successful design of these processes necessitates a profound understanding at the molecular level of how these substances interact with biological membranes. Thorough thermodynamic investigations provide invaluable insights into these interactions and aid in selecting suitable compounds for pharmaceutical production. This study aims to determine the density and speed of sound for D-calcium pantothenate in mixtures of water and deep eutectic solvents (DESs), specifically choline chloride/sucrose, choline chloride/ glucose, and choline chloride/ fructose (with 2:1 molar ratio) over a temperature range of 288.15 K to 318.15 K under atmospheric pressure. In order to predict the behavior of molecules, COSMO model (the Conductor-Like Screening Model) offer complementary strengths in quantum chemistry. This approach allows for calculating solvation free energies, making it ideal for predicting properties like solubility, where understanding solvent-solute interactions is crucial. By correlating the measured parameters using standard relationships, important partial molar parameters such as apparent molar volumes and apparent molar isentropic compressibility are calculated. Additionally, apparent molar isobaric expansion, and Hepler’s constant are derived from the density and speed of sound data. The experimental apparent molar volumes, and apparent molar isentropic compressibility data is fitted to the Redlich-Meyer equation to obtain significant quantities such as standard partial molar volume, and partial molar isentropic compression. The comprehensive thermodynamic analysis of this studied system holds immense significance for advancements in the pharmaceutical industry.

Molecular interaction studies of Gamma-aminobutyric acid (GABA) in an aqueous medium at various temperatures: A comprehensive analysis using volumetric, thermoacoustic and DFT methods

The interaction of Gamma-aminobutyric acid (GABA) in an aqueous medium at various concentrations (0.101–1.086) mol·kg−1 as a function of temperature is being studied using volumetric, viscosity and acoustic analysis. The calculation of apparent molar volume (VΦ), partial molar volume (V∅o), apparent molar isentropic compression (Kϕ) and partial molar isentropic compression (Kϕ0) of GABA in an aqueous medium has been done by measuring the densities and speed of the sound in the temperature range of 298.15–323.15 K. The thermo-acoustic parameters like adiabatic compressibility (βs), acoustic impedance (Z), intermolecular free length (Lf), relative association (RA), relaxation time (τ), internal pressure (πi), enthalpy (ΔH), Gibbs free energy (ΔG), and change in entropy (ΔS) are also computed. The strength of the hydrogen bond interaction of GABA in an aqueous medium and its dipole moment are calculated using single-point energy calculations. These calculations employ IEFPCM and PCM solvation models using DFT/B3LYP and MP2 methods with the 6-311G++ (d, p) basis set. The outcomes are interpreted in terms of hydrogen bond interactions that exist in the mixture.

Thermodynamically Traceable Calorimetric Results for Aqueous Sodium Chloride Solutions from T = (273.15 to 373.15) K up to the Saturated Solutions: Part 2 —The Quantities Associated with the Partial Molar Heat Capacity

AbstractIn previous articles (Partanen and Partanen in J. Chem. Eng. Data 65: 5226 − 5239 (2020), J. Solution Chem. 52: 1352 − 1385 (2023)), we presented a traceable and transparent three-parameter model for thermodynamic activity and enthalpy quantities in aqueous NaCl solutions. The model is based on extended Hückel equations with parameters B, b1, and b2 and it applies from T = 273.15 to 373.15 K up to the saturated solutions. These studies demonstrate that the model explains the literature data of almost all thermodynamic quantities including apparent and partial molar enthalpies within experimental error. In the model, the ion-size parameter in the Debye–Hückel equation, B, is regarded as a constant while the parameters of the coefficients of the linear and quadratic molality terms, b1 and b2, respectively, possess quadratic temperature dependences. In this study, the results obtained for the heat capacity quantities of NaCl(aq) are considered. We show that the available heat capacity literature for these solutions can be predicted at least satisfactorily up to the saturated solutions with our new model. Following this success, we supplement the existing thermodynamic tables with the new values for the relative apparent and partial molar heat capacities for NaCl solutions. It is likely that the new tables contain the most reliable values determined so far even though no calorimetric data were used in the parameter estimation of our model. Graphical Abstract

Analysis of molecular interactions of an aqueous benzoates with glycolic and lactic acid: spectroscopic, acoustic, and volumetric approach

Volumetric as well as Acoustic properties for the ternary liquid combination (water + sodium methyl p-hydroxybenzoate + glycolic acid/lactic acid) are evaluated at several temperatures using a Densimeter (DSA 5000 M) over the range of concentrations (0.000, 0.015, 0.025, 0.035) mol.kg−1. Several thermo-acoustical properties were computed utilizing the experimental data. These values were then used to derive several parameters, including the apparent molar volume( V∅ ); partial molar volume (V∅0); apparent molar isentropic compression (K∅,S); transfer properties(Δ V∅0, Δ K∅,s0 ); partial molar isentropic compression (K∅,s0); apparent molar expansibility ( E∅0 ) as well as its first derivative ( ∂Eϕ0/∂T ) P; and coefficient of thermal expansivity( αp ). The obtained results are explained by analyzing the several interactions that take place inside the liquid system by implementing the theory of co-sphere overlap. Utilizing these thermodynamical parameters, the interaction coefficients are computed to evaluate the ternary mixture corresponding to the interactions between solutes and solvents. FTIR spectrum analysis revealed the presence of H-bonds along with the other molecular interactions in the analyzed systems, as shown by the shifting of the O-H stretching band.

Investigation of intermolecular interactions in binary mixtures of N,N-dimethyl benzyl amine with higher alkanols (N,N-dimethyl benzyl amine with 1-octanol, 1-nonanol, 1-decanol)

ABSTRACT Measurements of densities (ρ), speeds of sound (u), and viscosities (η) for binary mixtures of N,N-dimethyl benzyl amine (DMBA) with 1-octanol (D1), 1-nonanol (D2), and 1-decanol (D3) were performed across temperatures from 303.15 K to 313.15 K under atmospheric pressure, covering all composition ranges. These experimental results were utilised to calculate the excess molar volume, excess isentropic compressibility, viscosity deviation, and the excess Gibbs free energy of activation for viscous flow. Calculations for partial molar properties and infinite dilution partial molar properties were also carried out for each binary mixture. The dominant intermolecular interactions within these mixtures were analysed using the PFP theory. Additionally, the Jouyban−Acree model was applied to predict the thermo physical properties such as density, speed of sound, and viscosity. The model’s accuracy was evaluated by comparing predicted values with experimental data through mean relative deviations (MRDs) and individual relative deviations (IRDs).

Excess Thermodynamic Properties and FTIR Studies of Binary Mixtures of Toluene with 2-Propanol or 2-Methyl-1-Propanol

Physical properties of the binary solutions, toluene with 2-propanol and 2-methyl-1-propanol, were measured at T = 293.15, 298.15, 303.15, 308.15, and 313.15 K and P = 100 kPa. The experimental density values were tested with the Emmerling et al. and Gonzalez-Olmos–Iglesias equations. The results indicate that the equation by Emmerling et al. is the best to correlate the density for toluene + 2-methyl-1-propanol system, while for toluene + 2-propanol, both proposed equations are proper to correlate the density with composition and temperature. The viscosity results were verified with different models containing two adjustable parameters. The values of viscosity deviation (∆η), excess molar volume (VE), excess Gibbs energy (ΔG*E), partial molar volumes (V1¯ and V2¯), and apparent molar volume (Vφ,1 and Vφ,2) were calculated. The values of the excess molar volume were positive for both systems, while negative values were obtained for the viscosity deviation and the excess Gibbs energy. The excess properties of the mixtures were adjusted to the Redlich–Kister equation. The values of thermodynamic functions of activation of viscous flow were computed and analyzed. Additionally, the Prigogine–Flory–Patterson (PFP) theory was applied to calculate VE and then compared with experimental values. The values of the percentage absolute average deviation obtained suggest the validity of this theory. The Fourier transform infrared spectroscopy (FTIR) spectra of the binary solutions studied in this work allowed for the understanding of the interactions between the molecules of these systems.

Acoustic and spectroscopic characterization of glycol ethers in vitamin B7 over the range of temperatures (288.15, 293.15, 298.15, 303.15) K

Density (ρ) and ultrasonic speed (u) of butoxyethanol and phenoxyethanol in aqueous solution of biotin concentrations (0.0012, 0.0017, 0.0022) mol·kg−1 at varying temperature range (288.15, 293.15, 298.15 and 303.15) K at 0.1 MPa were measured using Anton Paar DSA 5000 M. The volumetric and acoustical properties such as apparent molar properties (V∅), partial molar volume (V∅0),partial molar volume of transfer (ΔV∅0),apparent molar isentropic compression (K∅),partial molar isentropic compression (K∅0),partial molar isentropic compression of transfer are computed using the experimental data of density (ρ) and ultrasonic speed (u). This investigation is useful to understand the solvation behavior of biotin. Additionally, partial molar expansibilities (E∅0) along with their first order derivatives (∂E∅0/∂T)pare determined using the obtained experimental data. These results are effective in understanding the nature of interaction occurring inside the solution. Further, pair and triplet coefficients are evaluated which determines the structure making and breaking ability of glycol ethers in aqueous solution of biotin. Also, spectroscopic study of solutions is mentioned in current research which reveals the nature and strength of bond formation and various interactions in the mixture. The present study suggests the molecular interaction between the solute and solvent present in aqueous solution of Biotin (Vitamin B7) as solvent, butoxyethanol (BE) and phenoxyethanol (PE) as solute.

A molecular insight into the aggregation of cisplatin in aqueous solutions

Cisplatin (CPT), recognized as a widely used metallodrug, is a prevalent therapeutic agent for the treatment of various cancers. Given the diverse biological conditions in humans, as well as the aquatic environment within cells and the toxicity associated with CPT in cancer treatment, it is imperative to assess and optimize the solvation of CPT under various conditions. In this study, the influence of CPT on the structure of water is explored. In this regard, a systematic molecular dynamics (MD) simulation is employed to investigate the structure and dynamics of CPT in aqueous media, encompassing a range of concentrations from much diluted (0.05 M) to concentrated (5 M). The disruption of water structure by CPT molecules is determined using radial distribution function (RDF), mean-squared displacement (MSD), hydrogen bond number, and combined radial/angular distribution function (CDF). Notably, the CPT aggregates exhibit an impact on the average number of water-water hydrogen bonds. Through calculations of apparent and partial molal volumes of CPT at various concentrations, we observed a sudden and dramatic change in the solution structures up to the critical aggregation concentration of CPT (0.5 molal), a finding corroborated by the calculations of diffusion coefficients. In summary, the self-aggregation of CPT molecules commences at 0.5 molal, leading to increased apparent and partial molal volumes with rising concentration. However, beyond 0.5 molal, the change in volumes becomes less significant, suggesting that while the number of CPT aggregates continues to increase, their size remains relatively constant above this concentration.

Phase equilibria and volumetric properties of mixtures of highly fluorinated alcohols and water

New thermodynamic data are reported for aqueous solutions of highly fluorinated alcohols of different chain lengths. The liquid-liquid equilibrium (LLE) T-x diagram of the binary mixture (1H,1H-perfluoropropanol + water) was determined, as well as the LLE phase diagram of the ternary mixture (1H,1H-perfluoropropanol + 1-propanol + water) at 298.15 K and atmospheric pressure. The mutual solubilities of water with several linear perfluorinated alcohols (CF3(CF2)nCH2OH, n = 1–5) and the tertiary alcohol perfluoro-t-butanol ((CF3)3COH) were also measured at 298.15 K. Finally, volumetric properties such as the excess molar volumes and partial molal volumes at infinite dilution of the different fluorinated alcohols in water were also determined and discussed comparing with equivalent data from the literature for the corresponding hydrogenated alcohols.

Partial molar volumes of 1–1 electrolytes at high T and P: correlations and predictions

Knowledge of the partial molar volumes of aqueous ions allows accurate calculation of the pressure dependence of equilibrium constants, solubility of minerals, etc., thus being useful for thermodynamic modeling of hydrothermal processes. This study analyzed methods to correlate and predict the values of the partial molar volumes at infinite dilution, V2o, for 1–1 electrolytes and singly charged ions at elevated T and P. Since the precise experimental values of the dielectric constant of water are measured only up to 873 K, we were interested only in non-electrostatic ways to correlate V2o data. First of all, we compiled the V2o values at T > 373 K for the following 1–1 electrolytes: HCl, LiCl, LiI, LiNO3, LiOH, NaF, NaCl, NaBr, NaI, NaNO3, NaOH, NaHCO3, NaClO4, NaH2PO4, NaTr (Tr stands for triflate), KF, KCl, KBr, KI, KNO3, KOH, CsBr, and NH4Cl. Relations, following from the “density” model and from the Fluctuation Solution Theory (FST) were employed to analyze data. It was concluded that at the current state of knowledge of V2o the FST-relations for electrolytes are recommended mainly to reject strongly deviating experimental outliers. However, the “density” model provides a simple and fairly accurate way to describe the compiled set of data with only two parameters for each ion, n and Vhc, values of which were evaluated for the following singly-charged ions: H+, Li+, Na+, K+, Cs+, NH4+, F-, Cl-, Br-, I-, OH–, NO3–, H2PO4-, HCO3–, ClO4-, Tr- (Tr = triflate). Following Mesmer et al. (1988), we consider the fitting parameters Vhc and n to be related to the intrinsic volume of the ion and to the number of water molecules transferred from the bulk water to a hydration shell around the ion, respectively.Although the values of n and Vhc were fitted from data at temperatures from 373 to 673 K and water densities, do, from 0.5 to 1.1 g cm−3, apparently, they predict realistic V2o values at temperatures up to 1600 K and do ranges from 0.2 to 1.6 g cm−3.

Partial molar and microstructural properties of binary propane + o-toluidine system near the critical point of pure solvent based on the VLE measurements and modeling with CP-PC-SAFT and mg-SAFT equation of states

The isothermal VLE properties (PTxy relationship) of a binary supercritical (SC) C3H8 + o-toluidine mixture was measured by means of static-analytic method with fluid phase sampling at equilibrium conditions. The measurements were made at three temperatures of (393.15, 433.15, and 473.15) K and pressures up to 10.41 MPa. An experimental VLE apparatus, a high-temperature and high-pressure optical cell, has been used to measure the phase equilibrium properties (PTxy) of the binary SC C3H8 + o-toluidine mixture. The combined expanded absolute and relative uncertainties of the temperature, pressure, and the phase concentration measurements at 0.95 confidence level with a coverage factor of k = 2 is estimated at 0.15 K, 0.5 %, 4.2 % (for x) and 4.8 % (for y), respectively. The critical curve data, TC−x,PC-x, and PC− TC projections, have been derived based on the measured VLE data. The measured VLE and the derived critical curve data were used to estimate the theoretically important and physical meaning of Krichevskii parameter, ∂P∂xTCVC∞. Thermodynamic (partial molar properties, V¯2∞,H¯2∞,C¯P2∞, and distribution equilibrium constant KD), and microstructural (cluster’s size, Nexc∞) properties of infinite-dilute C3H8 + o-toluidine mixture near the critical point of pure solvent (C3H8) were calculated based on the derived Krichevskii parameter and pure solvent (SC C3H8) properties. CP-PC-SAFT and mg-SAFT equation of state (EoS), with zero interaction parameter, k12 = 0, for both models (pure prediction models, no adjustable parameters) were successfully applied to the present PTxy phase equilibria for the SC C3H8 + o-toluidine mixture. The present measured VLE data for C3H8 + o-toluidine system along with the reported pure compound properties of pure propane and o-toluidine have been used to examine the predictive capabilities of the theoretically based CP-PC-SAFT and mg-SAFT models of EoS. It was demonstrated that mg-SAFT is superior in predicting VLE of the C3H8 + o-toluidine system with k12 = 0.

On the size- and shape-dependence of integral and partial molar Gibbs energies, entropies, enthalpies and inner energies of solid and liquid nano-particles

In this paper the size- and shape dependences of 8 different integral and partial molar thermodynamic quantities are derived for solid and liquid nano-phases, starting from the fundamental equation of Gibbs: i) The integral molar Gibbs energies of nano-phases and the partial molar Gibbs energies of components in those nano-phases, ii) The integral molar enthalpies of nano-phases and the partial molar enthalpies of components in those nano-phases, iii) The integral molar entropies of nano-phases and the partial molar entropies of components in those nano-phases, and iv). The integral molar inner energies of nano-phases and the partial molar inner energies of components in those nano-phases. All these 8 functions are found proportional to the specific surface area of the phase, defined as the ratio of its surface area to its volume. The equations for specific surface areas of phases of different shapes are different, but all of them are inversely proportional to the characteristic size of the phase, such as the diameter of a nano-sphere, the side-length of a nano-cube or the thickness of a thin film. Therefore, the deviations of all properties discussed here from their macroscopic values are inversely proportional to their characteristic sizes. The 8 equations derived in this paper follow strict derivations from the fundamental equation of Gibbs. Only the temperature dependent surface energy of solids and surface tension of liquids will be considered as model equations to simplify the final resulting equations. The theoretical equations are validated for the molar Gibbs energy against the experimental values of liquidus temperatures of pure lead. The theoretical equations for the molar enthalpy are validated i). Against the experimental values of dissolution enthalpy differences between nano- and macro cobalt particles in the same liquid alloy and ii). Against the size dependent melting enthalpy of nano-indium particles. In this way, also the theoretical equations for the molar entropy and molar inner energy are validated as they are closely related to the validated equations for the molar Gibbs energy and molar enthalpy.

Ultrasonic and volumetric investigation of aqueous disodium EDTA with PEG 400 and PEG 4000 at different temperatures

Polyethylene glycol (PEG) 400 and 4000 thermodynamic characteristics in water-based disodium ethylenediaminetetraacetic acid solutions provide important clues about the nature of the intermolecular interactions taking place in this liquid environment. In order to make these determinations, the present study reports data for density and sound velocity at a variety of temperatures and then analyses the volumetric-acoustic features of the solutions. The experimental data for PEG 400 and PEG 4000, which are polyethylene glycols, were recorded at a constant atmospheric pressure of 0.1 MPa and at temperatures ranging from 288.15 to 318.15 K. The values were 0.007, 0.008, and 0.009 mol·kg−1. From the experimental density and speed of sound values, the following are computed: apparent molar properties, partial molar properties, partial molar transfer properties, and the partial molar expansibility, along with its first derivative and thermal expansion coefficient. According to the co-sphere overlap model, the results are described using these generated parameters, these are thought of as the type of interactions taking place within the combination. This study also uses partial molar characteristics to assess the pair interaction coefficients and triplet interaction coefficients.

Thermodynamic and transport properties of binary mixtures containing 1,2-propanediol with 2-methoxyethanol and 2-ethoxyethanol at different temperatures

In the present investigation density, speed of sound, and viscosity have been reported for binary liquid mixtures of 1,2-propanediol (1,2-PD) with 2-methoxyethanol (2-ME) and 2-ethoxyethanol (2-EE) over the entire composition range at T= (298.15–323.15) K. From the experimental data, excess molar volume, (VmE), excess isentropic compressibility, (κsE), excess molar isentropic compressibility, (κs,mE), excess speed of sound, (uE), excess isobaric thermal expansion,αpE, and deviation in viscosity (Δη) of liquid mixtures have been calculated. The excess partial molar volume,V¯m,1E, V¯m,2E , excess partial molar isentropic compressibility, K¯s,m,1EK¯s,m,2E over the whole composition range together with partial molar volume,V¯m,10, V¯m,20, partial molar isentropic compressibility K¯s,m,10,K¯s,m,20, excess partial molar volume,V¯m,10E, V¯m,20E and excess partial molar isentropic compressibility, K¯s,m,10E,K¯s,m,20E at infinite dilution have also been calculated. All excess properties have been correlated using the Redlich-Kister smoothing polynomial equation. The VmE results are analysed in the light of Prigogine-Flory-Patterson theory. Analysis of each of the three contributions viz. interactional, free volume, and P* to VmE has shown that interactional contribution and free volume effect are negative for all the mixtures, and P* contribution is positive for the mixtures of 2-ME. The variations of these parameters with changes in composition and temperature have been discussed in terms of intermolecular interactions prevailing in these mixtures. Further, the viscosities of these binary mixtures were correlated theoretically by using various empirical and semi-empirical models and the results were compared with the experimental findings.

Solvation behavior of chitosan monomers in aqueous [Hmim]CL solutions. Experimental and DFT studies

This paper reports densities and viscosities for the mixtures of D-glucosamine hydrochloride (GlcN·HCl) and N-acetyl-D-glucosamine (GlcNAc) with aqueous solutions of 1-hexyl-3-methylimidazolium chloride, [Hmim]Cl, between 293.15 and 318.15 K in 5 K increments and atmospheric pressure. Leveraging this data, we calculated volumetric properties such as apparent molar volume, Vϕ, limiting partial molar volume, Vϕ0, and standard molar volume of transfer, ΔVϕ0. We handled viscosity data to compute the viscosity B-coefficient and several activation parameters of viscous flow. Some of these are relevant in discussing interactions between monosaccharides (solute) and [Hmim]Cl (co-solvent) in aqueous media. The solute–solvent interactions were discussed based on ionic/ hydrophilic/ hydrophobic interactions using the co-sphere overlap model. ΔVϕ0 > 0 indicates that ionic/hydrophilic interactions predominate in the studied systems and are stronger in GlcN·HCl solutions than in GlcNAc at low [Hmim]Cl molalities. At higher [Hmim]Cl concentrations, decreasing values of ΔVϕ0 suggest the dominance of hydrophobic interactions over hydrophilic/ionic ones. We discuss (using Hepler’s constant and viscosity B-coefficient) the ability of monosaccharides to act as structure maker/breaker in aqueous [Hmim]Cl solutions. This indicates that GlcNAc is a better structure promoter than GlcN⋅HCl in aqueous [Hmim]Cl solutions. Finally, density functional theory (DFT) was used to model the molecular structure and compute the solute–solvent interaction energies using the GAMESS 2016 software.

The impact of thermophysical properties on eflornithine drug solute in acetone and ethyl acetate solvent interactions at varying concentrations and temperatures

The study was conducted on the impact of thermophysical properties on eflornithine drug solute–solvent interactions in aqueous ethyl acetate and acetone at different concentrations and temperatures. The aim of this study is to enhance the understanding of eflornithine’s behavior in different solvents, which is crucial for its effective use in pharmaceutical applications. The density, molar volume, viscometric, and conductometric characteristics of the eflornithine drug solutions (0.025, 0.05, 0.075, 0.1, and 0.125 mol/kg) in acetone and 25% (v/v) aqueous ethyl acetate were measured within a temperature range of 298.15 K–318.15 K. Based on the determined density parameters, the following parameters were assessed: viscosity (η), equivalent molar conductance, limiting apparent molar volume (V0φ), apparent molar volume of transfer (V0φtr), and apparent molar volume (Vφ). The Masson empirical relationship and the viscosity-to-Jones-Dole (JD) equation were used to evaluate the partial molar volume (Vφ), experimental slope (SV), viscosity, and density data. Temperature and concentration were used to determine each parameter. For each set of dilutions, conductometric studies were conducted in both study solvents. The gathered data was analyzed in order to evaluate the ion–solvent interactions. The Walden product Λomηo’s positive temperature coefficient values indicate that the drug eflornithine functions as a structural modifier in acetone and aqueous acetyl acetate systems. The structure-making and breaking characteristics of the polar solvents acetone and ethyl acetate were identified.

The retention factors and partial molar volumes of cycloartenyl ferulate at infinite dilution in supercritical carbon dioxide: Measurements and correlation

The retention factors and infinite dilution partial molar volumes of a solute in supercritical fluid are crucial for understanding solute–solvent interactions, analyzing pressure effects on chemical reactions, and optimizing industrial processes. Despite their importance, there is a notable scarcity of available data on retention factors and infinite dilution partial molar volumes in supercritical fluid systems. This study presents the first experimental data on the retention factors and partial molar volumes of cycloartenyl ferulate at infinite dilution in supercritical carbon dioxide. The retention factors were measured across temperatures ranging from 308.15 to 353.15 K and pressures of 8.20 to 31.03 MPa using supercritical fluid chromatography. The infinite dilution partial molar volumes were determined by taking the partial derivative of the retention factors with respect to the density of carbon dioxide. The obtained infinite dilution partial molar volumes range from −1.64 × 10−2 to 4.10 × 10−4 m3/mol, with large negative values observed near the critical point of carbon dioxide, indicating strong solvent–solute interactions. In this study, a new correlation model successfully predicts the experimental infinite dilution partial molar volumes with an average absolute relative deviation of 2.3 % over 86 data points.

Investigating micelle formation in systems with benzethonium chloride and n-lauroyl sarcosine sodium salt: The impact of thermal effects and ethyl lactate concentration using volumetric, statistical, acoustic, and molecular dynamic methods

Surface active agents (SAAs) are versatile molecules that possess the ability to serve as multifunctional ingredients in a wide range of consumer products across various industrial sectors. These molecules can act as wetting and dispersion agents, emulsifiers, foaming and anti-foaming agents, lubricants, and more. The objective of this study was to evaluate the effect of temperature, and ethyl lactate concentration on micelle formation in systems containing benzethonium chloride (BC) and N-lauroyl sarcosine sodium salt (NLSS). The experimental measurements were conducted at three equidistant temperatures i.e., 298.15 K to 318.15 K and pressure, P=0.1 MPa. Several volumetric as well as compressibility parameters including apparent molar properties (Vϕ,Kϕ,S), partial molar properties (Vϕ°,Kϕ,S°), transport properties (ΔtrVϕ°,ΔtrKϕ,S°), hydration number, etc. have been evaluated. A Bayesian two-factor design with uninformative priors was used to analyze the values of Vϕ°,and Kϕ,S°. It was possible to determine that the temperature factors, and the ethyl lactate (EL) addition significantly influence the results for Vϕ° while for Kϕ,S°it is not appreciable at 5 and 10 % in EL concentration when BC and NLSS systems is compared. The simulations of the micellization process show the impact of temperature, particularly in the presence of ethyl lactate, is evident in the structural and dynamic changes observed in the micelles. Specifically, as the temperature rises from 298.15 K to 318.15 K, the self-assembly process becomes more spontaneous and accelerated, leading to larger and more spherical micelles. These alterations in micelle size, shape, and orientation enhance their capacity to effectively solubilize hydrophobic substances. The computational simulations demonstrated that BC molecules exhibit spontaneous aggregation at the interface of polar-nonpolar systems, resulting in the formation of a monolayer. In this monolayer, the heads of the molecules are oriented towards the polar phase, while the hydrophobic tails are in the nonpolar phase. Similarly, the NLSS system exhibits a continuous and gradual process of self-organization over a period of 120 ns, where NLSS molecules naturally come together to create a single layer arrangement at the zigzag-shaped boundary.