Following the first part of this study, herein, we focus on the oil-wet rock surfaces formed by the adsorption of polar molecules via base interactions. The effects of ions on the oil–water wettability of quartz surfaces and the mechanism behind the phenomenon are revealed through contact angle measurements and surface characterization. The results indicate that the ions can greatly alter the wettability of the surface to become more water-wet only when the salt solutions are alkaline, with a maximum decrease of approximately 20° in the water contact angle. NaCl and KCl solutions are more effective than CaCl₂ and Na₂SO₄ solutions. In alkaline solutions, the hydroxyl ions can deprotonate the octadecylamine molecules to weaken their interactions with the surfaces, such that the cations can displace the adsorbed octadecylamine and lead to large desorption from the surfaces. Finally, a quantitative model is established to describe the ion-induced wettability alteration.

在本研究的第一部分之后，我们将重点介绍由极性分子通过碱相互作用吸附而形成的油湿岩石表面。通过接触角测量和表面表征，揭示了离子对石英表面的油水润湿性的影响及其现象的机理。结果表明，仅当盐溶液为碱性时，离子才能极大地改变表面的润湿性，从而变得更加水润湿，最大的水接触角降低约20°。NaCl和KCl溶液比CaCl ₂和Na ₂ SO ₄更有效解决方案。在碱性溶液中，氢氧根离子可以使十八烷基胺分子去质子化，从而减弱它们与表面的相互作用，从而使阳离子能够取代吸附的十八烷基胺，并导致表面上的大量脱附。最后，建立定量模型来描述离子诱导的润湿性变化。