Natural Resources Canada, CanmetENERGY Devon, 1 Oil Patch Drive, Devon, Alberta T9G 1A8, Canada.
Phys Chem Chem Phys. 2023 Feb 15;25(7):5638-5647. doi: 10.1039/d1cp04060j.
Understanding the interactions of petroleum asphaltenes with mineral surfaces is important for diluted bitumen spill response and modeling. In this study, molecular dynamics and umbrella sampling simulations are performed using interfacially active and non-interfacially active asphaltene model compounds individually positioned near each of the surfaces of kaolinite in the presence of explicit solvent environments containing water, toluene, and mixtures of toluene and water in varying proportions. The interfacially active asphaltene bonds the strongest to the silicon oxide surface of kaolinite in pure water and the bonding weakens to nearly zero in toluene-water mixtures. The non-interfacially active asphaltenes bond to kaolinites silicon oxide surface in water about half as strongly as the interfacially active one in water and the bonding weakens in the presence of toluene. The number of non-hydrogen bonded contacts between the interfacially active asphaltene and the aluminum hydroxide surface of kaolinite increases as the proportion of toluene is increased and the contacts with water are decreased. In these conditions, the non-interfacially active asphaltenes do not form non-hydrogen bonded contacts with kaolinite. On the silicon oxide surface, the number of non-hydrogen bonded contacts of all asphaltenes with kaolinite tends to decrease as the proportion of toluene is increased and the contacts with water are decreased. The number of hydrogen bonds of the interfacially active asphaltene with water decreases as the proportion of toluene is increased. The radii of gyration indicate that the interfacially active asphaltene is extended in water and when adsorbed on kaolinite, and becomes compact as the proportion of toluene is increased. The simulation results highlight the competitive interfacial interactions in the complex scenario of diluted bitumen spills in the presence of water and clay minerals.
了解石油沥青质与矿物表面的相互作用对于稀释沥青溢油的反应和模拟很重要。在这项研究中，使用界面活性和非界面活性的沥青质模型化合物分别在含有 explicit solvent 环境的水中靠近高岭石的各个表面进行分子动力学和伞状采样模拟，该溶剂环境包含水、甲苯以及不同比例的甲苯和水的混合物。在纯水中，界面活性沥青质与高岭石的氧化硅表面结合最强，而在甲苯-水混合物中结合减弱到几乎为零。非界面活性沥青质在水中与高岭石的氧化硅表面的结合强度约为界面活性沥青质在水中的一半，而在甲苯存在下结合强度减弱。界面活性沥青质与高岭石的氧化铝表面之间的非氢键接触数随着甲苯比例的增加而增加，而与水的接触数则减少。在这些条件下，非界面活性沥青质与高岭石不形成非氢键接触。在氧化硅表面上，所有沥青质与高岭石之间的非氢键接触数随着甲苯比例的增加而减少，而与水的接触数则减少。界面活性沥青质与水的氢键数随着甲苯比例的增加而减少。回转半径表明，界面活性沥青质在水中伸展，当吸附在高岭石上时变得紧凑，随着甲苯比例的增加而变得紧凑。模拟结果突出了在存在水和粘土矿物的稀释沥青溢油复杂情况下的竞争界面相互作用。
