分子动力学模拟阴离子/两性离子表面活性剂在油-水界面的分子行为及协同效应  

Molecular Dynamics Simulations of the Molecular Behavior and Synergistic Effect of Anionic/Zwitterionic Surfactants at Oil-Water Interface

作　　者：吴姁 夏瑜 苑莲花 员润 何绪文[1] WU Xu;XIA Yu;YUAN Lianhua;YUAN Run;HE Xuwen(College of Chemistry and Environmental Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)化学与环境工程学院,北京100083

出　　处：《石油学报（石油加工）》2021年第4期831-839,共9页Acta Petrolei Sinica(Petroleum Processing Section)

基　　金：国家水体污染控制与治理科技重大专项(2017ZX07402002-05)基金资助。

摘　　要：采用分子动力学模拟方法研究了表面活性剂十二烷基硫酸钠(SDS)/十二烷基磺丙基甜菜碱(SB12-3)混合体系在油-水界面的聚集行为以及SDS与SB12-3的协同作用。通过密度分布、界面厚度、界面形成能来分析油-水界面性质,当n(SDS)/n(SB12-3)=1/1时,协同效应达到最大,即混合体系的界面形成能(E_(IF))达到-640.959 kJ/mol。通过亲水基团的径向分布函数和氢键数目研究了SDS和SB12-3的亲水效应,发现SB12-3的亲水基团与水分子优先形成氢键,且形成氢键数目(12.555)大于SDS与水之间的氢键数目(8.968),SB12-3的亲水性更好;通过表面活性剂头基与尾链之间的夹角和疏水尾链序参数研究了2种表面活性剂的疏水性能,发现SDS烃链在油相中夹角(114.368°)大于SB12-3在油相中角度(111.903°),证明SDS拉伸程度好,表现出良好的疏水性能,2种表面活性剂的协同作用良好。The aggregation behavior of sodium dodecyl sulphate(SDS)/N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate(SB12-3)at the interface of oil-water and the interactions between SDS and SB12-3 were studied by molecular dynamics simulations.The interfacial properties of oil-water were analyzed by the density distribution,interfacial thickness and interface formation energy(E IF)and it is found that when the n(SDS)/n(SB12-3)=1/1,the optimal synergistic effect is achieved,where the E_(IF)value of the composite system reaches-640.959 kJ/mol.The hydrophilic effects of SDS and SB12-3 were studied by radial distribution functions(RDFs)and the numbers of hydrogen bonds.The results show that the hydrophilic groups of SB12-3 preferentially form hydrogen bonds with water molecules,which is greater than that between SDS and water molecules(12.555 versus 8.968),and the hydrophilicity of SB12-3 is better.The hydrophobic properties of the surfactants were studied by the angle between the head groups and tail chain,deuterium order parameters.The hydrophobicity of the two surfactants shows that the angle of SDS hydrocarbon chain in the oil phase is larger than(114.368°)SB12-3 in the oil phase(111.903°),indicating that the SDS has good tensile strength and good hydrophobicity,and the synergistic effect of the two surfactants is good.

关 键 词：分子动力学模拟 油-水界面 十二烷基硫酸钠 十二烷基磺丙基甜菜碱 

分 类 号：TE357[石油与天然气工程—油气田开发工程]