Yang Yafan, Wan Jingyu, Shang Xiangyu, Sun Shuyu
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China.
Computational Transport Phenomena Laboratory, Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
J Chem Phys. 2023 Sep 7;159(9). doi: 10.1063/5.0157957.
The fluid-solid interfacial tension is of great importance to many applications including the geological storage of greenhouse gases and enhancing the recovery of geo-resources, but it is rarely studied. Extensive molecular dynamics simulations are conducted to calculate fluid-solid interfacial properties in H2O + gas (H2, N2, CH4, and CO2) + rigid solid three-phase systems at various temperatures (298-403 K), pressures (0-100 MPa), and wettabilities (hydrophilic, neutral, and hydrophobic). Our results on the H2O + solid system show that vapor-solid interfacial tension should not be ignored in cases where the fluid-solid interaction energy is strong or the contact angle is close to 90°. As the temperature rises, the magnitude of H2O's liquid-solid interfacial tension declines because the oscillation of the interfacial density/pressure profile weakens at high temperatures. However, the magnitude of H2O vapor-solid interfacial tension is enhanced with temperature due to the stronger adsorption of H2O. Moreover, the H2O-solid interfacial tension in H2O + gas (H2 or N2) + solid systems is weakly dependent on pressure, while the pressure effects on H2O-solid interfacial tensions in systems with CH4 or CO2 are significant. We show that the assumption of pressure independent H2O-solid interfacial tensions should be cautiously applied to Neumann's method for systems containing non-hydrophilic surfaces with strong gas-solid interaction. Meanwhile, the magnitude of gas-solid interfacial tension increases with pressure and gas-solid interaction. High temperatures generally decrease the magnitude of gas-solid interfacial tensions. Further, we found that the increment of contact angle due to the presence of gases follows this order: H2 < N2 < CH4 < CO2.
液-固界面张力对包括温室气体地质封存和提高地球资源采收率在内的许多应用都非常重要，但很少有人对其进行研究。我们进行了广泛的分子动力学模拟，以计算在不同温度（298 - 403 K）、压力（0 - 100 MPa）和润湿性（亲水性、中性和疏水性）下，H₂O + 气体（H₂、N₂、CH₄和CO₂）+ 刚性固体三相系统中的液-固界面性质。我们在H₂O + 固体系统上的研究结果表明，在液-固相互作用能较强或接触角接近90°的情况下，气-固界面张力不应被忽略。随着温度升高，H₂O的液-固界面张力大小下降，因为在高温下界面密度/压力分布的振荡减弱。然而，由于H₂O的吸附更强，H₂O气-固界面张力大小随温度升高。此外，H₂O + 气体（H₂或N₂）+ 固体系统中H₂O - 固体界面张力对压力的依赖性较弱，而CH₄或CO₂系统中压力对H₂O - 固体界面张力的影响显著。我们表明，对于含有具有强气-固相互作用的非亲水性表面的系统，将H₂O - 固体界面张力与压力无关的假设谨慎地应用于诺伊曼方法。同时，气-固界面张力大小随压力和气-固相互作用增加。高温通常会降低气-固界面张力大小。此外，我们发现由于气体的存在导致的接触角增量遵循以下顺序：H₂ < N₂ < CH₄ < CO₂。
