烷基苯磺酸盐在油水界面行为的介观模拟

采用耗散颗粒动力学(DPD)方法在介观层次上模拟了表面活性剂烷基苯磺酸盐在油/水界面的排布行为, 考察了分子结构、浓度、盐度、油相等因素对表面活性剂界面密度和界面效率的影响, 并探讨了利用表面活性剂复配协同效应提高界面活性的理论机制. 分子模拟给出的分子水平的微观信息为强化采油技术中配方筛选和表面活性剂的有效应用提供指导.

Mesoscopic Simulation Study on the Behavior of Salt Alkylbenzene Sulphonate Adsorbed at Oil/Water Interface

With a simple coarse-grained model, the properties of sodium dodecylbenzene sulphonate (SDBS) adsorbed at the water/oil interface, has been investigated on a mesoscopic level by considering the variation of interfacial density using dissipative particle dynamics (DPD) simulation. Compared with sodium dodecyl sulphonate systems, sodium dodecylbenzene sulphonate are more efficient. An increase of surfactants interfacial concentration results in the increase of its interfacial density before reaching a full monolayer and appropriate salts make surfactant molecules adsorbed more at interface. It is beneficial to decrease interfacial tension if the hydrophobic chains of the surfactant and the oil have similar structure. The simulation conclusions are well consistent with the experimental results. Also with computer simulation method, we have observed that SDBS is not distributed homogeneously over the interface. Rather, the interfacial layer contains large cavities between SDBS clusters filled with water or oil clusters. When TX-100 molecules were introduced, clusters formed by nonionic surfactants filled SDBS cavities, thus decreased the interfacial tension to ultra low, even lower than 10^－3 mN?m^－1. This inhomogeneous distribution helps to enhance our understanding of the synergism interaction of the different surfactants.