Translational-rotational coupling parameters for mutual diffusion inN-octane (original) (raw)
Related papers
Application of rough hard-sphere theory to diffusion in n-alkanes
International Journal of Thermophysics, 1989
Tracer diffusion coefficients are reported for n-alkane solutes in n-dodecane, neicosane, n-eicosane, and n-octacosane in the temperature range 304-533 K at 1.38 MPa. Rough hard-sphere theory is used to interpret the data. The translational-rotational coupling parameters are determined for each solute-solvent pair at each temperature. The nature of the coupling parameter and the possibility of relating it to molecular properties and temperature in a homologous series are discussed.
Mutual diffusion coefficients for two n-octane isomers in n-heptane
International Journal of Thermophysics, 1989
A new instrument for the measurement of mutual diffusion coefficients in the liquid phase based on the Taylor dispersion technique has been developed. The instrument design and operation are described. The working region of the instrument has been established using an ideal model for the apparatus. The necessary design considerations and corrections to ensure that the instrument operates in accordance with the theory of the method are discussed. The accuracy of the experimental results is estimated to be + 1%. Experimental data for n-octane and 2,2,4-trimethylpentane at infinite dilution in n-heptane are reported. Correlation schemes based on the rough-hard sphere theory have been used to represent the experimental data and their predictive capability examined.
A correlation for predicting diffusion coefficients in alkanes
The Canadian Journal of Chemical Engineering, 1990
A correlation was developed for predicting limiting mutual diffusion coefficients of gaseous and liquid solutes in normal alkane solvents with carbon numbers ranging from 7 to 28 at temperatures to 570 K. The functional form of the correlation is based on the rough hard sphere theory. The parameters needed in the correlation are the molecular weights and hard sphere diameters of the solute and solvent molecules and molar volume of the solvent. The data used in the development of the correlation included 143 measurements with solute/solvent molecular mass ratios ranging from 0.005 to 2.26 and size ratios ranging from 0.3 to 1.3. The average absolute error in predictions was only 6.3%. When the correlation was used to predict literature values for binary n-alkane systems, the average absolute error was 16.7%.
Theory and Experiment of Binary Diffusion Coefficient of n-Alkanes in Dilute Gases
The journal of physical chemistry. A, 2016
Binary diffusion coefficients were measured for n-pentane, n-hexane, and n-octane in helium and of n-pentane in nitrogen over the temperature range of 300 to 600 K, using reversed-flow gas chromatography. A generalized, analytical theory is proposed for the binary diffusion coefficients of long-chain molecules in simple diluent gases, taking advantage of a recently developed gas-kinetic theory of the transport properties of nanoslender bodies in dilute free-molecular flows. The theory addresses the long-standing question about the applicability of the Chapman-Enskog theory in describing the transport properties of nonspherical molecular structures, or equivalently, the use of isotropic potentials of interaction for a roughly cylindrical molecular structure such as large normal alkanes. An approximate potential energy function is proposed for the intermolecular interaction of long-chain n-alkane with typical bath gases. Using this potential and the analytical theory for nanoslender b...
Modelling the Diffusion Coefficients of Dilute Gaseous Solutes in Hydrocarbon Liquids
International Journal of Thermophysics, 2021
In this work, we present a model, based on rough hard-sphere theory, for the tracer diffusion coefficients of gaseous solutes in non-polar liquids. This work extends an earlier model developed specifically for carbon dioxide in hydrocarbon liquids and establishes a general correlation for gaseous solutes in non-polar liquids. The solutes considered were light hydrocarbons, carbon dioxide, nitrogen and argon, while the solvents were all hydrocarbon liquids. Application of the model requires knowledge of the temperature-dependent molar core volumes of the solute and solvent, which can be determined from pure-component viscosity data, and a temperature-independent roughness factor which can be determined from a single diffusion coefficient measurement in the system of interest. The new model was found to correlate the experimental data with an average absolute relative deviation of 2.7 %. The model also successfully represents computer-simulation data for tracer diffusion coefficients ...
Journal of Chemical & Engineering Data, 2000
Taylor dispersion and differential refractometry are used to measure mutual diffusion coefficients (D) for the binary mixtures 1,4-dioxane + water, 1,3-dioxolane + water, and tetrahydrofuran + water at 25°C
Mutual diffusion coefficients of heptane isomers in nitrogen: A molecular dynamics study
The Journal of Chemical Physics, 2011
The accurate knowledge of transport properties of pure and mixture fluids is essential for the design of various chemical and mechanical systems that include fluxes of mass, momentum, and energy. In this study we determine the mutual diffusion coefficients of mixtures composed of heptane isomers and nitrogen using molecular dynamics (MD) simulations with fully atomistic intermolecular potential parameters, in conjunction with the Green-Kubo formula. The computed results were compared with the values obtained using the Chapman-Enskog (C-E) equation with Lennard-Jones (LJ) potential parameters derived from the correlations of state values: MD simulations predict a maximum difference of 6% among isomers while the C-E equation presents that of 3% in the mutual diffusion coefficients in the temperature range 500-1000 K. The comparison of two approaches implies that the corresponding state principle can be applied to the models, which are only weakly affected by the anisotropy of the interaction potentials and the large uncertainty will be included in its application for complex polyatomic molecules. The MD simulations successfully address the pure effects of molecular structure among isomers on mutual diffusion coefficients by revealing that the differences of the total mutual diffusion coefficients for the six mixtures are caused mainly by heptane isomers. The cross interaction potential parameters, collision diameter σ 12 , and potential energy well depth ε 12 of heptane isomers and nitrogen mixtures were also computed from the mutual diffusion coefficients.
Journal of Chemical & Engineering Data, 2008
Reference tables of second pVT-virial coefficients B͑T͒, viscosity ͑T͒, and selfdiffusion D͑T͒ are given for all neat alkanes C n H 2n+2 , n Ͻ 6, for temperatures T ഛ 1200 K starting at 100 K for CH 4 , 150 K for C 2 H 6 , and 180 K for C 3 H 8 , n-C 4 H 10 , i-C 4 H 10 , n-C 5 H 12 , i-C 5 H 12 , and C͑CH 3 ͒ 4 . Restricting ourselves to low densities the thermophysical properties are calculated by means of an isotropic ͑n-6͒ Lennard-Jones temperature dependent potential ͑LJTDP͒. In this model the potential well depth eff ͑T͒ and the separation at minimum energy R m ͑eff͒ ͑T͒ are explicitly temperature dependent, whereas the repulsive term n Ͼ 12 is independent of T. The LJTDP has been used before in order to construct reference tables of thermophysical properties of neat gases ͓Zarkova and Hohm, J. Phys. Chem. Ref. Data 31, 183 ͑2002͔͒ and binary mixtures ͓Zarkova, Hohm, and Damyanova, J. Phys. Chem. Ref. Data 32, 1591 ͑2003͔͒.
The Journal of Chemical Physics, 2005
We present results of theoretical study and numerical calculation of the dynamics of molecular liquids based on combination of the memory equation formalism and the reference interaction site model -RISM. Memory equations for the site-site intermediate scattering functions are studied in the mode-coupling approximation for the first order memory kernels, while equilibrium properties such as site-site static structure factors are deduced from RISM. The results include the temperature-density(pressure) dependence of translational diffusion coefficients D and orientational relaxation times τ for acetonitrile in water, methanol in water and methanol in acetonitrile, all in the limit of infinite dilution. Calculations are performed over the range of temperatures and densities employing the SPC/E model for water and optimized site-site potentials for acetonitrile and methanol. The theory is able to reproduce qualitatively all main features of temperature and density dependences of D and τ observed in real and computer experiments. In particular, anomalous behavior, i.e. the increase in mobility with density, is observed for D and τ of methanol in water, while acetonitrile in water and methanol in acetonitrile do not show deviations from the ordinary behavior. The variety exhibited by the different solute-solvent systems in the density dependence of the mobility is interpreted in terms of the two competing origins of friction, which interplay with each other as density increases: the collisional and dielectric frictions which, respectively, increase and decrease with increasing density.