Liquid Viscosity and Interfacial Tension of Binary and Ternary Mixtures Containing n-Octacosane by Surface Light Scattering

Abstract

In this study, the liquid viscosity and interfacial tension of binary and ternary mixtures containing noctacosane (n-C 28 H 58 ) and different byproducts typically found in the Fischer−Tropsch process were investigated. For the binary mixtures having mole fractions of the byproducts between 0.02 and 0.40, the effects of varying branching, alkyl chain length, and degree of oxygenation in selected byproducts on viscosity and interfacial tension were studied. In detail, the isomers n-decane, 2-methylnonane, and 4-methylnonane were used to study differences in branching for alkanes with the same molecular weight. The 1-alcohols ethanol and 1-dodecanol as well as the carboxylic acids formic acid and acetic acid imply variations in the alkyl chain length and degree of oxygenation. In addition, two ternary systems consisting of n-octacosane, n-decane, and ethanol with mole fractions of 0.6 of either n-alkane and 0.2 for each of the other two components were selected. On the basis of the surface light scattering (SLS) method analyzing microscopic surface fluctuations at macroscopic thermodynamic equilibrium, the liquid viscosity and interfacial tension of the studied mixtures could be determined at saturation conditions at temperatures from (373.15 up to 523.15) K with average expanded measurement uncertainties (k = 2) of (2.7 and 2.4)%. Except for systems containing the two branched alkanes showing a distinct decrease in the interfacial tension even at low mole fractions of 0.025, liquid viscosity and interfacial tension at 423 K are not strongly affected with increasing concentration of the byproducts up to 0.10 compared to the values for pure n-octacosane within relative deviations of 10% and 5%. For the studied binary and ternary systems, simple mixing rules for liquid viscosity and interfacial tension based on the corresponding properties of the pure components are discussed.

Viscosity, Interfacial Tension, and Density of Binary-Liquid Mixtures of n-Hexadecane with n-Octacosane, 2,2,4,4,6,8,8-Heptamethylnonane, or 1-Hexadecanol at Temperatures between 298.15 and 573.15 K by Surface Light Scattering and Equilibrium Molecular Dynamics Simulations

“…Alternatively, the mole fraction x i can be replaced by the mass fraction w i as or The use of the mass fraction in eqs and has the advantage of considering the mass of the individual mixture components. When the size and weight of molecules scale accordingly, e.g., mixtures of alkanes or alcohols with different carbon-chain lengths, such predictions already consider that larger molecules may have a larger impact on the mixture properties. ,, The following section will explore the reliability of such mixing rules for predicting the liquid density, liquid dynamic viscosity, and interfacial tension using the experimental results of the nine investigated mixtures from this work. For all three properties and all three systems, the AARDs of the discussed prediction models (according to eqs –) from the reported correlations of the experimental data with respect to temperature and composition (according to eqs , , and ) are provided in Table .…”

“…These properties are then used to determine the viscosity and interfacial tension of the liquid. For a detailed discussion of the relevant theory ,,,, and its application within thermophysical property research, − ,,− the reader is referred to the literature. The experimental setup and the measurement procedure and conditions are the same as in our previous studies. , In this work, only relevant information on the principles of the technique and the data evaluation is provided.…”

“…The influence of the pressure difference and, thus, of the density difference on η L and σ was calculated with the help of pressure-dependent density data for pure components and was found to be less than 0.1%. Uncertainties in η L and σ are calculated via an error propagation scheme , considering the uncertainties induced by the measured variables and adopted reference data or predictions. Total expanded relative measurement uncertainties ( k = 2), averaged over all investigated systems and temperatures, for η L and σ are determined to be U r ( η L ) = 2.0% and U r (σ) = 1.8%.…”

Viscosity and Interfacial Tension of Binary Mixtures of n-Hexadecane with Dissolved Gases Using Surface Light Scattering and Equilibrium Molecular Dynamics Simulations

“…Here, ρ and q refer to the density and the modulus of the wave vector, while Γ and ω q describe the damping and the frequency of the surface wave of a specific q -value. The reader is referred to the literature ,,, as well as to our previous studies on pure-component properties ,, or binary or ternary mixtures with or without dissolved gases ,, for a detailed description of the theory and application of this technique. A brief summary of the details relevant for this work is provided below.…”

Liquid Viscosity and Surface Tension ofn-Hexane,n-Octane,n-Decane, andn-Hexadecane up to 573 K by Surface Light Scattering

“…During the last two decades, research activities at the Department of Chemical and Biological Engineering (CBI) and at the Erlangen Graduate School in Advanced Optical Technologies (SAOT) of the Friedrich-Alexander-University Erlangen-Nürnberg (FAU) developed SLS as a reliable and accurate instrument in thermophysical property research of fluids covering broad ranges of viscosity and surface or interfacial tension. For various systems at the vapor–liquid equilibrium, for example, reference fluids (toluene, diisodecyl phthalate, carbon dioxide, and n -pentane), refrigerants, ,, hydrofluoroethers, ionic liquids, − linear and branched alkanes as well as mixtures of n -alkanes with other n -alkanes , or oxygenated derivatives, viscosity and surface or interfacial tension have been determined with typical measurement uncertainties ( k = 2) below 2% at temperatures between 233 and 573 K. For binary model systems, the simultaneous analysis of fluctuations at the surface and in the bulk of the fluid allowed for the determination of interfacial tension, viscosity, thermal diffusivity, and mutual diffusivity of the very same sample within one single SLS setup . Recently, we demonstrated the applicability of SLS for the investigation of multiphase systems in the vapor–liquid–liquid equilibrium, simultaneously measuring the viscosities of the two liquid phases and the vapor–liquid and liquid–liquid interfacial tensions …”