State Key Laboratory of Water Resource Protection and Utilization in Coal Mining, China Energy Investment Group, Beijing 102211, China.
School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China.
Molecules. 2023 Jun 14;28(12):4765. doi: 10.3390/molecules28124765.
The adsorption and detachment processes of n-dodecane (CH) molecules were studied on silica surfaces with variable surface chemistry (Q, Q, Q environments), using molecular dynamics simulations. The area density of the silanol groups varied from 9.4 to 0 per nm. The shrinking of the oil-water-solid contact line was a key step for the oil detachment, due to water diffusion on the three-phase contact line. The simulation results showed that oil detachment was easier and faster on a perfect Q silica surface which had (≡Si(OH))-type silanol groups, due to the H-bond formation between the water and silanol groups. When the surfaces contained more Q crystalline type which had (≡Si(OH))-type silanol groups, less oil detached, due to the formations of H-bonds among the silanol groups. There were no silanol groups on the Si-OH 0 surface. Water cannot diffuse on the water-oil-silica contact line, and oil cannot detach from the Q surface. The detachment efficiency of oil from the silica surface not only depended on the area density, but also on the types of silanol groups. The density and type of silanol groups depend on the crystal cleavage plane, particle size, roughness, and humidity.
采用分子动力学模拟研究了不同表面化学性质（Q、Q、Q 环境）的硅胶表面上正十二烷（CH）分子的吸附和解吸过程。硅醇基团的面积密度从 9.4 到 0 纳米-1 变化。由于水在三相接触线上的扩散，油-水-固接触线的收缩是油脱附的关键步骤。模拟结果表明，在具有（≡Si(OH))-型硅醇基团的完美 Q 硅胶表面上，油的脱附更容易且更快，这是由于水和硅醇基团之间形成氢键所致。当表面含有更多具有（≡Si(OH))-型硅醇基团的 Q 晶型时，由于硅醇基团之间形成氢键，脱附的油更少。在 Si-OH 0 表面上没有硅醇基团。水不能在油水硅接触线上扩散，油也不能从 Q 表面脱附。油从硅胶表面的脱附效率不仅取决于硅醇基团的面积密度，还取决于硅醇基团的类型。硅醇基团的密度和类型取决于晶体解理面、粒径、粗糙度和湿度。
