Calculation of the interfacial tension of the methane–water system with the linear gradient theory

The linear gradient theory (LGT) combined with the Soave–Redlich–Kwong (SRK EoS) and the Peng–Robinson (PR EoS) equations of state has been used to correlate the interfacial tension data of the methane–water system. The pure component influence parameters and the binary interaction coefficient for the mixture influence parameter have been obtained for this system. The model was successfully applied to correlate the interfacial tension data set to within 2.3% for the linear gradient theory and the SRK EoS (LGT-SRK) and 2.5% for the linear gradient theory and PE EoS (LGT-PR). A posteriori comparison of data not used in the parameterisation were to within 3.2% for the LGT-SRK model and 2.7% for the LGT-PR model. An exhaustive literature review resulted in a large database for the investigation which covers a wide range of temperature and pressures. The results support the success of the linear gradient theory modelling approach for this system.