【摘要】 研究了十二烷基硫酸钠(SDS)和甜菜碱(Betaine)以及复配体系在油水界面和气液界面的排布行为,探讨了温度、无机盐和复配比例对表面活性剂界面活性和泡沫稳定性的影响,重点探讨了多价无机阳离子对表面活性剂界面吸附行为和复配协同加合增效作用的影响,得到了海水为介质条件下两方面性能均较好的体系,取得的认识为高盐条件下低张力泡沫驱油体系的设计与应用提供理论依据和指导.更多还原

【Abstract】 In this paper,the molecular array behavior of anionic surfactant sodium dodecyl sulfate SDS and zwitterionic surfactant Betaine at the air/water and oil/water interfaces were investigated by molecular simulation approaches,which helped to understand the effects of temperature,salts and the proportion of components on the interfacial activity and foam stability of the mixed binary systems,especially how the multivalent inorganic cations influence the interfacial adsorption behavior of the surfactants and the synergistic effect.The oil/water interfacial tension was not only measured experimentally using TEXAS500 spinning drop interface tension meter,but also calculated theoretically using dissipative particle dynamic(DPD) method.Foam decay method was utilized to determine the foam stability.The array behavior of surfactant molecules at the air/water and oil/water interfaces was described by molecular dynamics(MD) simulation method.It was found that the oil/water interfacial activity of mixed binary system was significantly better than unitary system.The synergistic effect between SDS and Betaine was enhanced when there was Ca2+ or Mg2+ existed in the solution.The radial distribution function of head groups of surfactants around inorganic ions showed that there was very strong interaction between the Ca2+ or Mg2+and the head groups of SDS and Betaine,which not only induced the increase of the maximum interfacial adsorption quantity of the surfactants,but also adjusted the array states of the surfactant molecules in the interface layer.When the proportion of components of SDS/Betaine binary system was 4∶6,the oil/water interfacial activity and foam stability of the binary system both were very good with Ca2+ or Mg2+ existing,even use sea water as medium,which could be a good candidate system for foam system used under high salinity condition.The co-adsorption behavior of the surfactant molecules in the binary system at oil/water interface and the foam films was found to be similar.The simulation results agreed well with the experiment results.The knowledge about the microscopic character of the mixtures of surfactants at interfaces could provide useful guidance for the design and application of surfactants under the condition of high salinity,such as low tension foam flooding system used in offshore EOR.更多还原