Density and Temperature Dependencies of Liquid Surface Tension (original) (raw)
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Surface tension for pure fluids by molecular thermodynamic model and PHTC equation of state
Physics and Chemistry of Liquids, 2019
In this study, the modified square well model is combined with perturbed-hard-trimer-chain (PHTC) EOS to correlate the surface tension of normal alkanes and refrigerant fluids. The performance of the proposed model has been evaluated by calculating the surface tension of 15 hydrocarbons range within 112-440 K and pressures up to 4.72 × 10 −6 MPa. From 251 data points examined the average relative deviation (ARD) of the correlated and calculated densities and surface tension from the experimental ones was found to be 1.63% and 2.46%. Besides, some surface thermodynamic functions such as the surface entropy (S S) and surface enthalpy (H S) of studied liquids were also computed via our method. The ARD (in %) were found to be equal to 3.94 and 2.44, respectively. Finally, our method has also been employed to estimate the critical temperature of 15 hydrocarbons with ARD (in %) equal to 7.92.
2021
There are three interpretations of surface tension in the scientific literature based on phenomenological, thermodynamics and molecular dynamics arguments. The equivalence between phenomenological and thermodynamics interpretations is well known, but there is no explicit model to connect them with the principles of molecular dynamics. In molecular dynamics the concept of pressure is divided into two independent contributions referred as kinetic and cohesive. In this study a semi-empirical model of surface tension is proposed based on unbalanced intermolecular forces at the interphases. The model incorporates elements from the previous three interpretations and recognizes the existence of kinetic and cohesive contributions to pressure. Published experimental data of surface tension is used to determine the two model empirical parameters representing the thickness of interphases and average intermolecular forces. The results show that the proposed model correctly predicts a linear rel...
Surface Tension of Pure Hydrocarbons
International Journal of Thermophysics, 1998
A new correlation scheme for the surface tension of a homologous series of pure liquid hydrocarbons, as a function of molecular weight and temperature, is presented. Using orthobarie surface tension data from literature for four homologous series of hydrocarbons, i.e., n-alkanes, I-alkenes, cycloalkanes, and aromatics, the adjustable parameters for two new surface tension equations are obtained individualty for each series. The agreement between experimental values and those calculated with the two new generalized surface tension equations is very good, i.e., the temperature and molecular weight dependences of surface tension are welt reproduced.
Surface tension — A theoretical study of multicomponent solutions
Journal of Molecular Liquids, 2010
Surface tension of four quaternary (pentane + hexane + cyclohexane + benzene, pentane+ hexane+ benzene + toluene and pentane + cyclohexane + heptane + toluene, n-decane + n-hexane + cyclohexane + benzene) and six ternary (toluene + cyclohexane + carbon tetrachloride, benzene + cyclohexane + toluene, pentane + nhexane + benzene, n-hexane+ cyclohexane + benzene, cyclohexane + n-heptane + toluene and benzene + nhexane + carbon tetrachloride) mixtures containing alkanes at 298.1 5 K have been calculated by applying different approaches including :Altenberg (AL), Mc-Gowan (McG), Sanchez (SZ), Goldsack and Sarvas (GS), Flory Theory (FT) and Group Contribution method (GC). The results have been presented in terms of their average percentage deviation (APD) values and comparative studies have been done. An attempt has also been made to explain the nature of the molecular interactions and forces involved in these mixtures.
The Journal of Chemical Thermodynamics, 2011
Experimental surface tensions for binary mixtures (1,2-ethandiol + water), (1,2-ethandiol + acetonitrile), and (acetonitrile + water) at temperatures of 283.15 K, 298.15 K, and 308.15 K and the ternary mixture (1,2-ethandiol/water/acetonitrile) at 298.15 K have been measured with the Du Noüy ring tensiometer. The surface tension of the above mentioned binary and ternary systems were correlated with empirical and thermodynamic based models. The methods of Pando et al. and Ku et al. were used to correlate the ternary surface tension data. The Fu et al., Kalies et al. and Wang et al. models were also applied to predict surface tension in the ternary system. The mean average absolute deviations obtained from the comparison of experimental and calculated surface tension values for ternary system with three models are less than 2.4%, which leads to concluding that these models show a good accuracy in different situations in comparison with other predictive equations.
Surface tension regularity of non-polar, polar, and weak electrolyte liquid hydrocarbons
Fluid Phase Equilibria, 2005
The correlation of reduced surface tension σ * sc versus reduced temperature T * sc which produces family of linear curves is investigated for universality. Each curve is characterized by the reduced temperature index T * index which is included in T * sc . The correlation is based on phenomenological scaling law and consideration of law of corresponding states. The reduced temperature T * sc , scaled distance from the boiling temperature T b , has the practical advantage of being independent of critical temperature. The correlation is highly accurate when applied to 10 classes of non-polar, slightly polar, polar, and weak electrolyte liquid hydrocarbons. The slopes of linear curves of each class of liquids at given T * index 's are rather constant and a universal regularity among all liquid is very likely, however small differences identify three classes of non-polar, slightly polar, and polar plus weak electrolytes. Consideration of the pervious application to molten alkali halides, molten salts, and molten metals, and considering that the reduced surface entropy S s * = (∂σ * sc /∂T * sc ) is rather constant for all liquid tested, strengthen the idea that σ * sc -T * sc correlation is likely universal.
Surface tension of isomers of pure hydrocarbons: a method for estimation and prediction
Fluid Phase Equilibria, 2000
A new method to estimate and predict surface tension in the full liquid-state temperature range for isomers of pure hydrocarbons has been developed. The method requires as input parameters the surface tension value corresponding to the linear or normal member of a given hydrocarbon homologous series, modified by an empirical parameter here proposed for each isomer under study. This in turn is calculated using molar volume and solubility parameter values for both the normal and the isomer hydrocarbon. This new method was used to calculate surface tension values for 56 isomers of n-alkane and four isomers of the 1-alkene homologous series in the range 253-373 K. The average error obtained from a comparison between experimental and calculated surface tension values for 497 points of the 60 isomers considered was only 1.5%. The developed method may also be used to obtain surface tension data with high reliability above and below the temperature range for which experimental data are available for both normal and isomer hydrocarbons.
Surface tension of aqueous binary solutions at low temperatures
International Journal of Thermophysics, 1997
The paper is concerned with measurenaents of the surface tension of aqueous binary solutions at low temperatures. The eflects of both temperature and concentration on the surface tension of CaCI,. NaCIO~, and propylene glycol have been investigated. A differential capillary-rise method was employed lbr the measurements. The results showed that the surface tension of CaCI 2 and NaCIO~ increases monotonically as the concenm~tion of the solution increases, while for the propylene glycol solution the surlace tension decreases with increasing concentration. The surface tension of the testing liquids was found to be an almost-linear function of temperature from 20'~C to just above the freezing temperature. Equations lbr the surface tension of the three aqueous binary solutions as a function of temperature and concentration are presented.