Molar Enthalpies Of Binary Mixtures Research Articles

Measurement and Modeling of Excess Molar Enthalpies of Binary Mixtures Involving Hydrocarbon Components of Fuel

Experimental excess molar enthalpies of binary systems that are constituted by different groups of hydrocarbons, which are 1-hexene, methylcyclohexane, cyclohexane, isooctane, and heptane, are repo...

Application of the UNIFAC models for prediction and description of excess molar enthalpies for binary mixtures of n-propanol, acetic acid, n-propyl acetate, and water

In this paper the ability of the UNIFAC methods (original UNIFAC and modified UNIFAC (Dortmund)) to predict the excess molar enthalpies, HE, is considered. The predicted and the obtained earlier experimental values of the excess molar enthalpies for 5 binary systems of n-propanol, acetic acid, n-propyl acetate, and water were compared. Since the both methods represent the HE unsatisfactorily, new set of group interaction parameters of the UNIFAC (Dortmund) method for mentioned above compounds was evaluated.

Excess molar enthalpies of binary mixtures of n-octane, isooctane and cyclooctane with morpholine, 1,4-dioxane, piperidine, oxane, N-methyl piperidine and cyclohexane. Experimental results and DISQUAC modelling

Excess molar enthalpies, HE, for octane isomers (n-octane, isooctane and cyclooctane) + heterocycles (morpholine, 1,4-dioxane, piperidine, oxane and N-methyl piperidine) or + cyclohexane binary mixtures, were determined at 308.15 K and atmospheric pressure, using a flow calorimeter. All the mixtures are endothermic, over the whole range of compositions, except cyclooctane + cyclohexane which presents very small, positive and negative, excess molar enthalpies. HE values fall as follows: morpholine > 1,4-dioxane > piperidine > oxane > N-methyl piperidine > cyclohexane and n-octane > isooctane > cyclooctane. The purely physical model, DISQUAC, based on the rigid lattice theory developed by Guggenheim, was relatively well tested.

Excess molar enthalpies for binary mixtures of different amines with water

The isothermal excess molar enthalpies for binary mixtures of different amines with water were measured with a C-80 Setaram calorimeter. The experimental results indicate that the excess molar enthalpy is related to the molecular structure. The experimental excess molar enthalpies were satisfactorily fitted with the Redlich–Kister equation. They were also used to test the suitability of the NRTL model, and the deviations are a little larger than the R–K equation.

Excess molar enthalpies for binary mixtures of n-propanol, acetic acid, and n-propyl acetate at 313.15 K and atmospheric pressure

Excess molar enthalpies, HE, for the binary mixtures of acetic acid (AcOH)+n-propanol (n-PrOH), acetic acid (AcOH)+n-propyl acetate (n-PrOAc), and n-propanol (n-PrOH)+n-propyl acetate (n-PrOAc) have been measured at 313.15K and atmospheric pressure using the Setaram C80 calorimeter. The experimental results are presented and correlated with the Redlich–Kister polynomial equation and its modified version. Modeling of the excess enthalpies has been performed using the UNIFAC and NRTL models.

Excess molar enthalpies for binary mixtures of cyclopentanone, cyclohexanone, or cycloheptanone with n-nonane at T = 298.15 K and atmospheric pressure

Excess molar enthalpies, HE, for the binary mixtures of cyclopentanone, cyclohexanone, or cycloheptanone with n-nonane were measured at T=298.15K and 0.1MPa, by means of a Setaram Tian-Calvet MS80 microcalorimeter. All the binary systems investigated show endothermic behaviour (positive values) over the whole mole fraction range. The molar excess enthalpies decrease as the size of the cycloalkanone increases. The experimental results of HE are fitted to the Redlich–Kister equation to correlate the composition dependence. The experimental HE data are also used to test the suitability of the Wilson, NRTL, and UNIQUAC models. The correlation of excess enthalpy data in these binary systems using the UNIQUAC model provides relatively the most appropriate results.

Excess Molar Enthalpies of Binary Mixtures Containing 1-Methyl-3-octyl-imidazolium Tetrafluoroborate and Alcohols at T = 298.15 K

An isothermal titration calorimeter was used to measure the excess molar enthalpies (HE) at T = 298.15 K for five binary systems: 1-methyl-3-octyl-imidazolium tetrafluoroborate (OmimBF4) + alcohols (ethanol, 1-propanol, 2-propanol, 1-butanol, and 1-pentanol). The values of HE were found to be all positive for the five systems and were fitted with the Redlich–Kister polynomial and the UNIQUAC mode. The magnitude order of HE for the five systems was explained by the balance between the magnitude orders of enthalpies of the alcohol/alcohol and the alcohol/OmimBF4 interactions.

Excess molar enthalpies of binary mixtures of formamide with butanol at 298.15 K: Application of Prigogine–Flory–Patterson theory and Treszczanowicz–Benson association model

Excess molar enthalpies (HmE) of formamide (1)+1-butanol or 2-methyl-1-propanol or 2-methyl-2-propanol (2) mixtures have been measured at 298.15K over the entire composition range using flow micro calorimeter. The excess enthalpy data along with previously published excess volumes data (VmE) (M. Rani, S. Maken, J. Ind. Eng. Chem. 18 (2012) 1694) have been utilised to study the thermodynamics of molecular interactions in terms of Prigogine–Flory–Patterson theory and Treszczanowicz–Benson association model with a Flory contribution term. The Treszczanowicz–Benson model was developed for alkane+alkanol systems considering Mecke–Kempter type of association in alkanol. In this paper the Treszczanowicz–Benson association model was applied, for the first time, to binary mixtures containing both components associated (butanol and formamide) through hydrogen bonding. In both the cases, when either of formamide or butanol was assumed to be associated, the calculated HmE and VmE values compared reasonably well with the corresponding experimental data, but the agreement is not very impressive for excess enthalpy in formamide+2-methyl-2-propanol mixtures. Extent of inter-molecular H-bonding in formamide and butanols in their binary mixtures was also reflected in their molar enthalpy of association of H-bonding ΔhH0.

Excess molar enthalpies for binary mixtures of 1,2-dichloroethane with ethers at 298.15 K and atmospheric pressure

Excess molar enthalpies, HE, for the binary mixtures of 1,2-dichloroethane (1,2-DCE) with diethyl ether (DEE), methyl 1,1-dimethylethyl ether (MTBE), diisopropyl ether (DIPE), 1,3-dioxolane (1,3-DIOXO), 1,4-dioxane (1,4-DIOXA), tetrahydropyran (THP), ethylene glycol dimethyl ether (EGDME), diethylene glycol dimethyl ether (DEGDME), and diethylene glycol diethyl ether (DEGDEE), have been measured at 298.15K and atmospheric pressure, using a Setaram Tian-Calvet C80 microcalorimeter. All the binary systems investigated are characterized by exothermic mixing over the entire composition range, except for 1,2-DCE+DIPE which presents a S-shape HE behavior. The experimental HE data have been fitted to the Redlich–Kister polynomial equation.

Excess molar volumes and excess molar enthalpies for binary mixtures of 1,2-dichloropropane with methyl ethanoate, methyl propanoate, and methyl butanoate at T = 298.15 K

The excess molar volumes V m E and excess molar enthalpies H m E have been measured for the binary mixtures of {1,2-dichloropropane + methyl ethanoate, or +methyl propanoate, or +methyl butanoate} using a densimeter and an isothermal microcalorimeter, respectively, at T = 298.15 K and P = 1 atm. The H m E values of all binary mixtures are negative while V m E values are positive over the whole composition range. Both V m E and H m E values decrease with an increase of molecular weight of methyl esters. The maximum negative values of H m E for these binary systems were observed at x 1 = 0.45–0.51. But, the maximum positive values of V m E lie at 0.49–0.65 mole fraction of 1,2-dichloropropane. The experimental results are discussed in terms of intermolecular interactions, particularly the self-association by dipole–dipole attraction between like and unlike molecules and formation of empty space around the molecules in the mixtures. The experimental data were correlated by three local-composition models (Wilson, NRTL, and UNIQUAC). Out of three models, NRTL equation provides the most appropriate correlating results except the binary system containing methyl butanoate.

Excess molar enthalpies of binary mixtures containing 2-decanone or dipentyl ether with long-chain n-alkanes at T = 298.15 K

Excess molar enthalpies ( H E) of binary mixtures of 2-decanone or dipentyl ether with n-alkanes, including n-dodecane, n-tetradecane, and n-hexadecane, were measured with an isothermal titration calorimeter (ITC) at T = 298.15 K under atmospheric pressure. All the measured H E values are positive over the entire range of composition, indicating that all these mixing processes are endothermic. The H E values varying with composition are found to be nearly symmetric for each binary system. It was also shown that the H E values follow the order of n-hexadecane > n-tetradecane > n-dodecane at a given composition in either the 2-decanone or dipentyl ether binary systems. An empirical Redlich–Kister equation correlated quantitatively these new H E data. The Peng–Robinson and the Patel–Teja equations of state, and the NRTL model were also applied to fit the H E results. Among these tested correlative models, the Patel–Teja equation of state with two adjustable binary interaction parameters generally yielded the best representation.

Excess molar enthalpies for binary mixtures of trimethyl phosphate with alkanols {CH 3(CH 2) nOH, n = 0–3} at 298.15 K

The excess molar enthalpies ( H m E ) for the binary mixtures of trimethyl phosphate (TMP) with alkanols {CH 3(CH 2) n OH, n = 0–3} have been measured with an isothermal calorimeter at 298.15 K and atmospheric pressure. The H m E values are positive for all the mixtures over the whole composition range. The values increase in the order methanol < ethanol < 1-propanol < 1-butanol. The experimental results have been correlated with the Redlich–Kister equation.

(Vapour+liquid) equilibria and excess molar enthalpies for binary mixtures containing N,N-dialkylamides and 1-chloroalkanes

Abstract Isothermal (vapour + liquid) equilibria (VLE) and excess molar enthalpies H m E have been measured for liquid (N,N-dimethylformamide or N,N-dimethylacetamide + 1-chlorobutane, or + 1-chlorohexane, or + 1-chlorooctane mixtures). The VLE data have been reduced using the Redlich–Kister equation taking into consideration the vapour phase imperfection in terms of 2nd molar virial coefficients. The experimental results show that both H m E and G m E are positive and increase with increasing chain length of the 1-chloroalkane.

Excess molar enthalpies of binary mixtures for (tributyl phosphate+methanol/ethanol) at 298.15 K

Abstract Excess molar enthalpies of binary mixtures for tributyl phosphate (TBP)+methanol/ethanol were measured with a TAM air Isothermal calorimeter at 298.15 K and ambient. The results for xTBP+(1–x)CH3OH are negative in the whole range of composition, while the values for xTBP+(1–x)C2H5OH change from positive values at low x to small negative values at high x. The experimental results have been correlated with the Redlich–Kister polynomial. IR spectra of the mixtures were measured to investigate the effect of hydrogen bonding in the mixture.

Excess molar enthalpies of binary mixtures containing ethylene glycols or poly(ethylene glycols) + ethyl alcohol at 308.15 K and atmospheric pressure

Excess molar enthalpies, H m E , of binary mixtures containing ethylene glycols and poly(glycols) + ethyl alcohol were measured by a flow microcalorimeter at 308.15 K and at atmospheric pressure over the whole composition range. Binary mixtures contain ethyl alcohol + ethylene glycol, + di(ethylene glycol), + tri(ethylene glycol), + tetra(ethylene glycol), + poly(ethylene glycol)-200, + poly(ethylene glycol)-300, + poly(ethylene glycol)-400, + poly(ethylene glycol)-600. Effects of the molecular weight distribution (MWD), of the polymer were investigated too, by preparing three additional samples of poly(ethylene glycol) with the same number average molecular weight ( M n ≈ 300), but different MWD. For all mixtures, results were fitted to the Redlich–Kister polynomial. H m E curves are asymmetrical, showing positive values which vary from 280 J mol −1 (diethylene glycol + ethyl alcohol) to 1034 J mol −1 (mixture containing PEGs (200 + 400) + ethyl alcohol). Effects of changes in the glycols chain length and in MWD on the molecular interactions among the mixture components are discussed.

Excess molar enthalpies of binary mixtures of 1-hexene with some cyclic and aromatic hydrocarbons at 298.15 K

Microcalorimetric measurements of excess molar enthalpies, at 298.15 K, are reported for the four binary systems formed by mixing 1-hexene with the cycloalkanes: cyclohexane and methylcyclohexane, and with the aromatic hydrocarcons: benzene and toluene. Smooth Redlich–Kister representations of the results are presented. It was found that the Liebermann–Fried model also provided good representations of the results.

Excess molar enthalpies of binary mixtures containing poly(ethylene glycol) 200+four cyclic ethers at (288.15, 298.15 and 313.15) K and at atmospheric pressure

Excess molar enthalpies, H m E, of binary mixtures containing poly(ethylene glycol) (PEG) 200+1,3-dioxolane, PEG 200+1,4-dioxane, PEG 200+oxolane and PEG 200+oxane were determined using a flow microcalorimeter at (288.15, 298.15 and 313.15) K and at atmospheric pressure. The H m E curves are always positive, with maxima varying from 393 J mol −1 (1,3-dioxolane) to 658 J mol −1 (oxolane), showing asymmetrical trends. The effect of the temperature is well marked on the calorimetric data that increase as the temperature is increased. The Redlich–Kister polynomial was used to estimate the binary fitting parameters. Root-mean-square deviations from the regression lines are reported.

Excess volume, excess enthalpy and vapour–liquid equilibria of N, N, N′, N′-tetramethyl-1,3-butanediamine + n-heptane or + cyclohexane mixtures

Experimental data are reported of excess molar volumes and excess molar enthalpies of binary mixtures of N, N, N′, N′-tetramethyl-1,3-butanediamine + n-heptane or + cyclohexane at 298.15 K. The vapour pressures of the same binaries were also measured by a static method between 273.15 and 363.15 K at 10 K intervals. The molar excess Gibbs energies, calculated from the vapour liquid equilibrium data, and the molar excess enthalpies are used to test the applicability of group-contribution (DISQUAC) model. In particular, the possibility is tested to analyse the intramolecular effects (proximity effect).

Excess Molar Enthalpies for Binary Mixtures of Benzyl Alcohol and Heptanone Isomers at Different Temperatures

Excess molar enthalpies for the binary mixtures of benzyl alcohol + 2-heptanone, + 3-heptanone, + 5-methyl-2-hexanone, and + 2,4-dimethyl-3-pentanone were measured over the entire composition range at (298.65, 303.55, and 308.50) K using a Calvet-type microcalorimeter. The excess molar enthalpies are positive for all the mixtures with their maximums between (300 and 500) J·mol-1. The Redlich−Kister polynomial was used to correlate the experimental results. The experimental results are discussed in terms of intermolecular interactions, particularly hydrogen-bonding interactions between like and unlike molecules.

Excess molar enthalpies of binary mixtures containing pine resins in the range 288.15–313.15 K, and at atmospheric pressure: Use of the extended cell model of Prigogine

Excess molar enthalpies, H m E, of binary mixtures containing ( S)-(−)-limonene+α-pinene, + β-pinene, or+ p-cymene were determined using a flow microcalorimeter in the range 288.15–313.15 K, and at atmospheric pressure. The H m E are always positive, not exceeding 114 J mol −1, and curves show a symmetrical trend. The temperature dependence of the calorimetric data is slight. Results were correlated to the Redlich–Kister polynomial and the adjustable parameters were determined by the least-squares method. Results were also interpreted by an extended modified cell model of Prigogine.