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Deep eutectic solvents (DES) are engaging for their vast area of applicability, inexpensiveness, and easiness of handling compared to their ionic liquid analogous. In the current study, a set of DESs containing choline chloride/ ethylene glycol is synthesized in 1:2 and 1:3 M ratios. Physical properties of the prepared DESs including densities and viscosities were measured within the temperature range of 298.15–318.15 K at the pressure of 871 hPa. Moreover, a comparison between structural and physicochemical properties of these DESs was made by employing molecular dynamic simulation in a wide temperature range 298.15–398.15 K. The most reliable force filed model (FFM) for these eutectic mixtures acquired from the literature and exploited to get trustworthy physicochemical (density), transport (self-diffusion coefficient, viscosity, ionic conductivity), and some structural (radial distribution functions, spatial distribution function, hydrogen bonding) properties.

In this work an equation of state was presented for ionic liquids that can be derived using the average intermolecular potential (6, 3). This equation of state predicts the linear behavior of ( Z − 1) υ 2 versus ρ . It was shown that two types of temperature dependency relations for the equation of state parameters are applicable. The superiority of the temperature dependency relations for the proposed equation of state parameters respect to the corresponding relations for Farzi et al. and Tait equations of state parameters was investigated. The density, the isothermal compressibility, and the isobaric expansivity of ionic liquids were calculated using the presented equation of state. The percentage of the average absolute relative deviation for density prediction was 0.05% and for the isothermal compressibility and the isobaric expansivity was in the limit of the reported values in literatures.

In the present study, a new equation of state (EOS) was derived by using the thermodynamic equation of state and the intermolecular potential (3, 9, 12). It was shown that the EOS is applicable in low and high ranges of temperature, pressure and density for gaseous, liquid and supercritical fluids and even in liquid–gas phase transition region. The new EOS is applicable for a variety of fluids such as polar, nonpolar, rare gases, short-chain and long-chain hydrocarbon fluids. The absolute percent deviation of the calculated density for gaseous, liquid and supercritical fluids is very low. The common bulk modulus point and the common compression point regularities were predicted by the new EOS. The new EOS was compared with some equations of state which had been derived similarly. It is shown that the repulsive potential used in the EOS derivation is effective in predicting correct fluid properties.

The corrosion of iron carbide was investigated in the water at 298 K and 500 K as a weak electrolyte and a solution of hydrochloric acid at 298 K, using the reactive force field molecular dynamics. The thickness of the passive film, the formed species, and two-dimensional radial distribution function were investigated. The species FeO5H10, FeO4H8, and FeO3H6 were recognized as the products of corrosion reaction in the water at 500 K and FeO5H10, FeO4H8, and FeO5H9 in acidic solution at 298 K. The quantum mechanics calculations have shown that the more stable products in water and acidic solution are FeO4H8 and FeO5H9, respectively.

Proton conductivity of Na3 (2, 4, 6-trihydroxy-1, 3, 5-benzenetrisulfonate) framework (β-PCMOF2) is studied in anhydrous and humid conditions using molecular dynamics simulation in the temperature range of 303-423 K. To obtain results compatible with experiments force field parameters for proton is adjusted. The Grotthuss mechanism for proton conduction of β-PCMOF2 is proved by obtaining an activation energy in the range of ( − 0.261, − 0.101 eV). The effect of the electric field on proton conductivity is also investigated. Proton conduction is reduced with temperature which is in agreement with the experiments. The RDF plots obtained in the absence of electric field and the effect of electric field on the proton MSD show that the protons transport through the oxygen atoms of sulfonate groups of the framework and their movements in the x and y directions are more than that in the z-direction. Simulations are carried out in the presence of protonated water and 1, 2, 4-triazole molecules rejected possibility of the vehicle.

Four known regularities; including the common bulk modulus, the common compression point, Tait–Murnaghan and the linear behavior of the P – T isochors; are investigated for the hard core one Yukawa (HCOY) and hard core double Yukawa (HCDY) fluids. It is shown that the HCOY fluid is not able to predict the common bulk modulus and the common compression points properly. While, these regularities are observable in the HCDY fluids and it can be shown that the common intersection point occurs where contribution of the repulsion terms to the equation of state is equal to that of attraction terms. The effect of hard core potential shape on these regularities is also investigated. The results show that the application of the hard convex core in HCDY equation of state just affect the common bulk modulus and common compression points slightly, but has no significant effect on other studied regularities.

An expression has been derived for radial distribution function (RDF) at contact, g(σ), for a real fluid by the use of linear isotherm regularity (LIR). This expression, which is related to intermolecular interaction, can be used to describe the temperature–density dependency of RDF at contact, g(σ,ρ,T). The expression is used for prediction of surface tension of liquid alkali metals in Evan's expression using Lang–Kohn surface energy and in molecular dynamic results for surface tension. Application of some approximation to Evan's expression shows that a correct selection of surface energy in the resultant expression for surface tension yields values that are in good agreement with the experiment. The surface tension of liquid alkali metals has been obtained from the molecular dynamic studies using g(σ,ρ,T) and SE/NkB ≈ S2/NkB, where S2 is related to two particle correlations. The calculated surface tension of liquid alkali metals is in good agreement with the experimental values. The calculated values of surface tension using g(σ,ρ,T) are in better agreement with the experiment than those of the hard sphere model.

Expressions for direct correlation function, C ( Q ), and structure factor, S ( Q ), of liquid alkali metals (Na, Rb, Cs) and simple dense fluids (Ar, Kr) have been derived using the linear isotherm regularity (LIR). Unlike previous models, it is shown in this work that C ( Q ) and, consequently, S ( Q ) can be obtained without employing any specific potential; only p-v-T experimental data have been used for the calculation of C ( Q ) and S ( Q ). With these expressions, it is possible to determine the height and position of the first peak of S ( Q ) with an acceptable accuracy. The limiting of S ( Q ) at Q = 0 is calculated and compared with the values obtained experimentally, and those calculated from the extended random phase approximation (ERPA) and random phase approximation (RPA) models. We have used the derived expressions for S ( Q ) of liquid alkali metals and simple dense fluids for prediction of the pressure and density derivatives of S ( Q ) in the vicinity of the first peak.

In the present work the existence of a common compression factor point for binary mixtures has been investigated, both experimentally and theoretically. We found that the linear isotherm regularity (LIR) is able to predict the common compression factor point and the common bulk modulus point for binary mixtures, as well as pure dense fluids. An important conclusion deduced from this work is that a physical interpretation for such points may be given using LIR. The LIR along with the mean geometric approximation (MGA) have been used to relate the density at the common points of a mixture to those of its pure components. The numerical investigation shows that such a relation may be represented by a quadratic function in terms of the system composition for most mixtures. However, we have found that such a quadratic relation is generally valid for all investigated mixtures. An important result obtained from this work is that we may get information about the magnitude of interactions between unlike molecules, ...

A general equation of state, originally proposed for compressed solids by Parsafar and Mason, has been successfully applied to dense fluids. The equation was tested with experimental data for 13 fluids, including polar, nonpolar, saturated and unsaturated hydrocarbons, strongly hydrogen bonded, and quantum fluids. This equation works well for densities larger than the Boyle density ρB [1/ρB=T B d B 2(T B)/T], where B2(TB) is the second virial coefficient at the Boyle temperature, at whichB 2=0 and for a wide temperature range, specifically from the triple point to the highest temperature for which the experimental measurements have been reported. The equation is used to predict some important known regularities for dense fluids, like the common bulk modulus and the common compression points, and the Tait-Murnaghan equation. Regarding the common points, the equation of state predicts that such common points are only a low-temperature characteristic of dense fluids as verifed experimentally. It is also found that the temperature dependence of the parameters of the equation of state differs from those given for the compressed solids. Specifically they are given byA 1 (T)=a 1+b1T+c1T2-d1 T ln (T).

The micellar properties of beta-casein in solution with a homologous series of cationic surfactants have been investigated using turbidity, fluorescence spectroscopy, and quenching fluorescence measurements. Turbidity measurements indicated that monomeric cationic surfactants initially bind cooperatively with a site on the beta-casein micelle in negatively charged amino acids. This leads to the formation of low-soluble beta-casein micelle-monomeric surfactants complexes. Further addition of surfactant leads to the formation of more highly soluble complexes of beta-casein micelle-cationic surfactant. The fluorescence experiments were also used to study the formation of beta-casein-cationic surfactant complexes and to determine critical micelle concentration of surfactants and beta-casein. The mean aggregation number of beta-casein and cationic surfactant micelles at various experimental conditions and the dependence of aggregation phenomenon on the chain length of cationic surfactants were investigated. The mean aggregation number for beta-casein micelle has been determined to be 45.70 using quenching fluorescence.