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Density, ρ, and viscosity, η, of pure components of 2-aminoethanol, 1-butanol, and 3-amino-1-propanol, along with the binary mixtures of {x12-aminoethanol + x21-butanol}, {x13-amino-1-propanol + x2...

In this work, the density, ρ, and viscosity, η, of pure components 1-propanol, 2-propanol, 3-amino-1-propanol, and 2-butanol along with binary mixtures of {x12-butanol + x21-propanol}, {x12-butanol...

Densities, ρ, viscosities, η, and refractive indices, n D, for 1-hexyl-3-methyl imidazolium chloride ([hmim]Cl) (IL), 1-pentanol, and ethylene glycol (EG), and for the binary mixtures {x 1[hmim]Cl + x 21-pentanol} and {x 1[hmim]Cl + x 2EG} were measured over the entire composition range at temperatures (293.15–333.15) K and ambient pressure. The excess molar volumes, $$ V_{\text{m}}^{\text{E}} $$ , and viscosity deviations, Δη, for the binary mixtures were calculated from the experimental data. The $$ V_{\text{m}}^{\text{E}} $$ values of {x 1[hmim]Cl + x 21-pentanol} mixtures are negative over the entire composition range at all temperatures, and increase with increasing temperature in the alcohol rich region and decrease with increasing temperature in the IL rich range. The $$ V_{\text{m}}^{\text{E}} $$ values of {x 1[hmim]Cl + x 2EG} mixture are positive in the alcohol rich range and negative in the IL rich range at all temperatures, and decrease with increasing temperature. Viscosity deviations of both mixtures are negative over the entire composition range at all temperatures and decrease with increasing temperature. The excess molar properties were correlated by Redlich–Kister equation, and the excess molar volumes were correlated using the PFP model. The fitting parameters and standard deviations were determined.

Densities, ρ, and viscosities, η, of pure isobutanol, 1-amino-2-propanol, and 1-propanol, along with their binary mixtures of {x 1isobutanol + x 21-propanol}, {x 11-amino-2-propanol + x 21-propanol}, and {x 11-amino-2-propanol + x 2isobutanol} were measured over the entire composition range and at temperatures (293.15–333.15) K at ambient pressure (81.5 kPa). Excess molar properties such as the excess molar volume, V m E , partial molar volumes, $$ \bar{V}_{1} $$ and $$ \bar{V}_{2} $$ , excess partial molar volumes, $$ \bar{V}_{1}^{\text{E}} $$ and $$ \bar{V}_{2}^{\text{E}} $$ , thermal expansion coefficient, α, excess thermal expansion coefficient, α E, viscosity deviation, Δη, and the excess Gibbs energy of activation, ∆G E*, for the binary mixtures were calculated from the experimental values of densities and viscosities. The excess values of the binary mixtures are negative in the entire composition range and at all temperatures, and increase with increasing temperature. Viscosity deviations, Δη, are negative over the entire composition range and decrease with increasing temperature. The viscosities of the mixtures were correlated by the models of McAllister, Heric, Hind, Katti, and Nissan. The obtained data were correlated by Redlich–Kister equation and the fitting parameters and standard deviations were determined.

In this paper, to study the possible intermolecular interactions in the binary mixtures 2-butanol with monoethanolamine, values of density were measured at temperatures 293.15 to 323.15 K and atmospheric pressure (P = 0.0815 MPa). From experimental densities, values of excess molar volume, VmE thermal expansion coefficient, α excess thermal expansion coefficient, αE and isothermal coefficient of excess molar enthalpy, (∂HmE/∂P)T, x were calculated. Excess molar volume is negative for the mentioned binary mixture over the whole range of concentration and becomes more negative with the increase in the temperature. ERAS model with the six adjustable parameters was used to correlate the excess molar volumes at different temperatures. Agreement between experimental data and predicted values through this model was reasonable at all temperatures. The maximum standard deviation for the mentioned binary mixture was 1%. Also, PC-SAFT model with one adjustable parameter and different schemes (2B, 3B, 4C) was applied to correlate the binary densities. A comparison among the performance of three approaches shows that the scheme 3B-2B at 293.15 K with the average absolute deviation (AAD) 1.63% has the best agreement with experimental data. When the PC-SAFT model with the prediction ability (p = 0) was implemented, the minimum of AAD increased to 4.66%.

Density and viscosity of pure components 1-hexyl-3-methylimidazoliumtetrafluoroborate ([Hmim][BF 4 ]), 2-methyl-2-propanol, and propylamin, along with binary mixtures of { x 1 [Hmim][BF 4 ] + x 2 2-methyl-2-propanol}, { x 1 [Hmim][BF 4 ] + x 2 propylamin}, and { x 1 2-methyl-2-propanol + x 2 propylamin}, and ternary mixture of { x 1 [Hmim][BF 4 ] + x 2 2-methyl-2-propanol + x 3 propylamin} were measured over the entire composition range at atmospheric pressure and 298.15 K. The results of measuring the density and viscosity were used to calculate the excess molar volumes, partial molar volumes, and viscosity deviations. For all of the binary mixtures, the computed excess molar volumes were correlated by applying Redlich–Kister equation and Prigogine–Flory–Patterson (PFP) theory, while the obtained viscosities were correlated using McAllister, Hind, and Nissan equations. The obtained excess molar volumes, V m E , and viscosity deviations, Δη , of all of the binary mixtures and ternary mixture are negative over the entire composition range. The Cibulka equation was used to correlate the ternary excess molar volumes and viscosity deviations using the Redlich–Kister parameters of the binary mixtures.

Density and viscosity of binary mixtures of {x1isobutanol + x21-propanol}, {x1isobutanol + x22-propanol}, and {x13-amino-1-propanol + x21-propanol} were measured over the entire composition range and from temperatures (293.15 to 333.15) K at ambient pressure. The excess molar volumes and viscosity deviations were calculated and correlated by the Redlich–Kister and McAllister equations, respectively. The excess molar volumes are negative over the entire mole fraction range for all of the mixtures and become more negative with increasing temperature. The viscosity deviations of the binary mixtures are negative in the entire composition range and decrease with increasing temperature.

Density and viscosity of binary mixtures of (x13-amino-1-propanol + x2isobutanol) and (x13-amino-1-propanol + x22-propanol) were measured over the entire composition range and from temperatures (293.15 to 333.15) K at ambient pressure. The excess molar volumes and viscosity deviations were calculated and correlated by the Redlich–Kister (RK) equation. The thermal expansion coefficient and its excess value, isothermal coefficient of excess molar enthalpy, and excess partial molar volumes were determined by using the experimental values of density and are described as a function of composition and temperature. The excess molar volumes are negative over the entire mole fraction range for both mixtures and increase with increasing temperature. The excess molar volumes obtained were correlated by the Prigogine–Flory–Patterson (PFP) model. The viscosity deviations of the binary mixtures are negative over the entire composition range and decrease with increasing temperature.

In this work, densities, ρ, and viscosities, η, of pure 1-hexyl-3-methylimidazoliumtetrafluoro borate {[C6mim][BF4]}, 3-amino-1-propanol (AP), and isobutanol, along with their binary mixtures of {x1[C6mim][BF4] + x2AP} and {x1[C6mim][BF4] + x2isobutanol} were measured over entire composition range at ambient pressure (81.5 kPa) and in the temperature range of (303.15 to 338.15) K. The excess molar volume, V m E , thermal expansion coefficient, α, and its excess value, αE, isothermal coefficient of excess molar enthalpy, ( ∂ H m E / ∂ p ) T , x , and viscosity deviation, Δη, for both of the mixtures were calculated from the experimental values of densities and viscosities. The values of V m E for binary mixture of {x1[C6mim][BF4] + x2AP} shows a S-shaped dependence on composition with positive values in the [C6mim][BF4] rich-region and negative values at the opposite extreme, and increase with increasing temperature. This quantity is negative for binary mixture of {x1[C6mim][BF4] + x2isobutanol} in the entire composition range and increases with increasing temperature. Viscosity deviations, Δη, are negative over the entire composition range and decrease with increasing temperature for both of the mixtures. These data were correlated by Treszczanowiczb–Benson and Redlich–Kister equations, and the fitting parameters and standard deviations were determined. The Prigogine–Flory–Patterson theory has been used to correlate the excess molar volumes of the mixtures.

Density, ρ , and viscosity, η , of pure 1-hexyl-3-methylimidazoliumtetrafluoroborate ([C 6 mim][BF 4 ]), 2-propanol, and binary mixture of { x 1 [C 6 mim][BF 4 ]+ x 2 2-propanol} were measured at atmospheric pressure and in the temperature range of (293.15 to 333.15) K. The excess molar volume, V m E , thermal expansion coefficient, α p , excess thermal expansion coefficient, α p E , and isothermal coefficient of excess molar enthalpy (∂ H m E /∂ p ) T , x , were calculated from the experimental values of density. The excess molar volumes are negative over the entire mole fraction range for this mixture and increase with increasing temperature. These data have been used to examine the applicability of Extended Real Associated Solution (ERAS) model in correlating the excess molar volume of the binary mixture. The viscosity values of the binary mixture were calculated via McAllister equation and the obtained results show a good agreement between the experimental and the calculated values in the whole composition range and all temperatures, so that the relative deviations are rarely more than 2%. The excess molar properties were correlated with the Redlich–Kister equation.

Densities, ρ, and viscosities, η, of pure 1-hexyl-3-methylimidazoliumtetrafluoro borate ([C6mim][BF4]) and 1-propanol, and their binary mixture {x1[C6mim][BF4] + x21-propanol} were measured at atmospheric pressure and in the temperature range of 293.15–333.15 K. The excess molar volumes, V m E , thermal expansion coefficients, α, and their excess values, αE, isothermal coefficient of excess molar enthalpy, ( ∂ H m E / ∂ p ) T , x and excess viscosities, ηE, were calculated from the experimental values of densities and viscosities. The excess molar volumes of the binary mixture are negative over the entire mole fraction range and increase with increasing temperature. Excess viscosities are negative over the entire mole fraction range of the mixture and decrease with increasing temperature. The obtained excess molar volumes and excess viscosities were correlated with the Redlich–Kister equation. The experimental results have also been used to examine the applicability of Prigogine–Flory–Patterson (PFP) theory in predicting the excess molar volume of the binary mixture. It is indicated that agreement between excess molar volumes calculated via PFP theory and the experimental results is good in all temperatures.

A molecular thermodynamic model is developed to predict DNA melting in ionic and crowded solutions. Each pair of nucleotides in the double-stranded DNA and each nucleotide in the single-stranded DNA are respectively represented by two types of charged Lennard-Jones spheres. The predicted melting curves and melting temperatures T(m) of the model capture the general feature of DNA melting and match fairly well with the available simulation and experimental results. It is found that the melting curve is steeper and T(m) is higher for DNA with a longer chain. With increasing the fraction of the complementary cytosine-guanine (CG) base pairs, T(m) increases almost linearly as a consequence of the stronger hydrogen bonding of the CG base pair than that of adenine-thymine (AT) base pair. At a greater ionic concentration, T(m) is higher due to the shielding effect of counterions on DNA strands. It is observed that T(m) increases in the presence of crowder because the crowder molecules occupy a substantial amount of system volume and suppress the entropy increase for DNA melting. At a given concentration, a larger crowder exhibits a greater suppression for DNA melting and hence a higher T(m). At the same packing fraction, however, a smaller crowder leads to a higher T(m).

A simple correlation function for the thermal conductivity of liquid methane has been obtained. The correlation has then been extended to other light alkans such as ethane, propane and iso-butane by introducing four adjustable parameters, which are fluid dependent. The obtained correlation is applicable in the temperature range 200–400 K and the pressure range 5–20 MPa. The mean relative errors for the calculated thermal conductivities are rarely greater than 3% for all cases.

In the present work, an analytical expression has been obtained for the direct correlation function (DCF). Derivation of this relation was based on the well known statistical mechanical relation between bulk modulus and DCF. Analytical expression of the bulk modulus has been derived using Ihm-Song-Mason (ISM) equation of state (EoS), and we have used the hyper netted chain (HNC) approximation for the DCF in terms of the density expansion. Applying the obtained DCF makes possible to have structure factor (SF) at any given thermodynamic state. We have calculated the SF in this way for liquid argon and compared the results of our calculations with the experimental data at different temperatures and densities and at almost entire range of the attractive and repulsive of inter atomic distances. The agreement between the calculated SF and the experimental data are qualitatively reasonable.

Densities of the binary liquid mixtures of 2-ethyl-1-butanol + dibutyl ether (DBE) or ethylene glycol mono butyl ether (EGMBE), 2-methyl-1-butanol + DBE, have been measured as a function of the composition at temperature range of 293.15 to 313.15 K and atmospheric pressure. The measurements have been carried out using an Anton Paar model DMA 4500 oscillating u-tube densitometer. The excess molar volume, V m E , the excess thermal coefficient, α E , and the isothermal expansion coefficient of excess molar enthalpy, (∂ H m E /∂ P ) T,x , were calculated from the experimental densities. It is indicated that the excess molar volume is negative for 2-methyl-1-butanol + DBE over the entire mole fraction range, and decreases with increasing temperature. The V m E value is positive for the binary mixture of EGMBE + 2-ethyl-1-butanol over the entire mole fraction range, and decreases with increasing temperature. This quantity is negative for the binary mixture of 2-ethyl-1-butanol + DBE over the entire mole fraction range, and decreases with increasing temperature in the limit of pure ether and increases with increasing temperature in the limit of pure alcohol. The excess molar volumes were correlated with Redlich–Kister equation.

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.

In this work, a simple coordination number (C.N.) model for the (9, 3) Lennard–Jones (LJ) fluid is obtained. It is based on the comparison of the internal pressure derived from a given equation of state (EoS) with the internal pressure derived from the (9, 3) LJ fluid as an effective pair potential (EPP). This model reproduces well the thermodynamic properties of the fluid such as internal energy, and the C.N. which is comparable with the Monte Carlo simulation data for the C.N. in the high-density region. In addition, the obtained C.N. can predict the first shell radial distribution function, g(r), of the fluid as well.

In this work, based on the variational inequality minimizing (VIM) theory of statistical thermodynamics and using the (6,12) Lennard-Jones potential function as an effective pair potential (EPP), analytical expressions for the temperature and density dependencies of the EPP parameters have been obtained. The resulting equation of state can predict thermodynamic properties such as internal energy and Helmholtz free energy for simple dense fluids such as Ar, CO, N 2 , and CH 4 with differences less than 5%.

A variational theory (VT), in which the potential energy of a real system is evaluated relative to the hard-sphere system, has been used to investigate the medium's effects on the pair potential parameters. By adding the medium's effects to the isolated pair potential, the concept of an “effective pair potential” (EPP) has been introduced. The advantage of such a potential (EPP) over the isolated pair potential is that the configurational energy can exactly be written as the sum of all EPP of all pairs available in the system. The parameters of such a pair potential will then show state dependence. The EPP parameters for different dense fluids at various temperatures have been obtained via the VT, and they have been shown to be density independent for densities greater than the Boyle density, ρ B ≃1.8ρ c , (where ρ c is the critical density), while at lower densities the parameters depend on density as well as temperature. For any dense fluid, the depth of the EPP, e, is found to be larger than its corresponding isolated pair. When the EPP parameters are used to reduce temperature and density, the cut-off parameter, C=d/σ depends only on the reduced density, and this parameter shows a strong principle of corresponding states for different fluids. The resulting expression for the cut-off parameter has then been used to accurately predict the internal energy. Finally, the EPP parameters are compared with those of the average effective pair potential (AEPP) for Ar, to show the importance of the medium effects and the long-range interactions of the AEPP in dense fluids, individually. This comparison shows that the depth parameter of the AEPP is much larger than that of the EPP. Since the long-range interactions are mainly attractive, such a conclusion is reasonable.

Recently, using the linear isotherm regularity (LIR) equation of state, the average effective pair potential parameters for dense fluids have been calculated, and it was shown that they are only temperature dependent. Those parameters were used to propose a strong principle of corresponding states. In the present work, the approach is extended to binary mixtures, from which we have found that the average effective pair potential parameters of mixtures depend on composition and temperature. We have also calculated the average effective unlike pair potential parameters of mixtures at various temperatures via the LIR parameters. The calculated like and unlike pair potential parameters of some mixtures have then been used to calculate their excess enthalpy. When the calculated average effective pair potential parameters of mixtures are used to reduce the LIR parameters, a strong principle of corresponding states has been observed for various mixtures with different compositions, as for the pure components. The calculated like and unlike pair potential parameters have been tested with different mixing rules based on the one-fluid approximation. The maximum differences of the calculated values with the mixing rules are lower than 10%.

In this work, a simple function for the viscosity of liquid methane has been obtained. The obtained function then has been used for other light hydrocarbons such as ethane, propane, and iso-butane with introducing four adjustable parameters. The magnitudes of these adjustable parameters are dependent on the sample. The differences of the calculated viscosity of the samples via the obtained correlation function with the experimental data are less than 5% in the determined regions.