Experimental study of hydrogen-brine interfacial tension: Implications for natural hydrogen production

Experimentally determined interfacial tensions (IFT) of the H 2 –NaCl (aq) system are reported, with NaCl molalities of (0, 1, 3 and 5) mol·kg −1 at temperatures from (298.15 to 423.15) K and pressures from (0.5 to 30) MPa. Measurements were conducted using the pendant drop method. The IFT was found to decrease with increasing temperature and pressure, while increasing NaCl concentration led to higher IFT. Surface tension values extrapolated from the IFT data showed good agreement with literature values, validating the reliability of the measurements. A linear dependence of IFT on NaCl molality was identified, enabling development of an empirical correlation incorporating temperature, pressure, and NaCl molality that fits the experimental data well, with an average absolute deviation of 0.24 mN⋅m −1 . These results provide a validated dataset for modelling interfacial phenomena in hydrogen-water/brine systems relevant to geological hydrogen production and storage. • IFT data for H 2 –H 2 O and H 2 –NaCl (aq) measured using pendant drop method. • IFT decreases with T and p , and increases with NaCl molality. • Surface tensions extrapolated from IFT agree with literature within 1.4%. • A linear relationship between IFT and NaCl molality was identified. • Empirical model correlates IFT with T , p , and NaCl molality within 2 mN⋅m −1 .