Modeling interfacial tension of (CH₄+N₂)+H₂O and (N₂+CO₂)+H₂O systems using linear gradient theory

The linear gradient theory (LGT) of fluid interfaces in combination with the cubic-plus-association equation of state (CPA EOS) is applied to determine the interfacial tensions of (CH₄+N₂)+H₂O and (N₂+CO₂)+H₂O ternary mixtures from 298-373 K and 10-300 bar. First, the pure component influence parameters of CH₄, N₂, CO₂ and H₂O are obtained. Then, temperature-dependent expressions of binary interaction coefficient for (CH₄+H₂O), (N₂+H₂O) and (CO₂+H₂O) are correlated. These empirical correlations of pure component influence parameters and binary interaction coefficients are applied for ternary mixtures. For (CH₄+N₂)+H₂O and (N₂+CO₂)+H₂O mixtures, the predictions show good agreement with experimental data (overall AAD-1.31%)