Understanding and enhancing carbon dioxide (CO₂) solubility and interfacial behavior in saline aqueous systems are critical for improving the efficiency of subsurface CO₂ sequestration and related applications. In this study, diamine-functionalized silica nanoparticles were synthesized using N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS) and systematically evaluated for their ability to enhance CO₂ solubility and reduce CO₂ –brine interfacial tension (IFT) under reservoir-relevant conditions. CO₂ solubility measurements were conducted in fresh water, formation brine (FB), and single-salt solutions with controlled ionic strength over a wide range of temperatures (25–80 °C) and pressures (up to 300 bar). The results show that the synthesized nanoparticles significantly enhance CO₂ solubility in both low- and high-salinity environments, with an optimal nanoparticle concentration of 2000 ppm. Despite the strong salting-out effect observed at elevated ionic strength, nanoparticle addition consistently mitigated salinity-induced solubility reduction. IFT measurements further confirmed that AEAPTMS-functionalized silica nanoparticles effectively reduce CO₂–brine IFT across all investigated pressures. The combined solubility and interfacial results demonstrate that surface-engineered silica nanoparticles provide a robust and effective strategy for improving CO₂ –aqueous phase interactions in complex brine systems. This work offers new mechanistic insights into nanoparticle-assisted CO₂ behavior and highlights the potential of chemically tailored nanomaterials for enhancing CO₂ storage performance in saline reservoirs.
Cheraghi et al. (Sat,) studied this question.