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Interfacial tension in water/n-decane/naphthenic acid systems predicted by a combined COSMO-RS theory and pendant drop experimental study

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The interfacial tension of systems containing water, n-decane, and model naphthenic acids were investigated using a predictive model based on COSMO-RS theory and experimental pendant drop measurements. Five naphthenic acid homologues that are considered to be representative of surfactants inherent to crude oil were dissolved in n-decane at equal concentrations. The interfacial tensions of the five systems at an acid concentration of 1.66 mol% relative to n-decane were experimentally determined to be 27-30 mN/m. The interfacial tensions of the five different acid-decane phases against water were also predicted using density functional theory (DFT) calculations and COSMO-RS theory. The accuracy of the predictions was very good as confirmed through pendant drop measurements of the interfacial tension. The mean-absolute deviation between experimental and predicted values was 2.6 mN/m thus demonstrating the high predictive power of COSMO-RS theory for calculating the interfacial tension at oil-water interfaces in the presence of surface-active compounds.
OriginalsprogEngelsk
TidsskriftMol. Phys.
ISSN1362-3028
DOI
StatusE-pub ahead of print - 16 jun. 2020

ID: 240409494