【作者】 丁伟； 刘国宇； 于涛； 曲广淼；

【Author】 Ding Wei~* Liu Guoyu Yutao Qu GuangMiao (College of Chemistry Engineering,Daqing Petroleum Institute,Heilongjiang Daqing,163318)

【机构】 大庆石油学院化学化工学院；

【摘要】 通过分子动力学模拟方法(MDS),用GROMACS软件模拟十二烷基磺酸钠异构体一1-苯基十二烷基磺酸钠、3-苯基十二烷基磺酸钠、5-苯基十二烷基磺酸钠在油/水界面的排布行为,研究给出了由油、水和十二烷基苯磺酸钠异构体组成的体系从初始"均相"到"油水两相"分离的动力学过程,考察十二烷基苯磺酸钠异构体的分子结构(苯环在1,3,5位)、浓度和不同油相在界面分离过程中的影响及作用。选取的力场为Gromos96改进力场,水分子使用较成熟的简单点电荷SPC(simplepoint charge)模型,且分别以氯仿、辛烷、癸烷、十二、十四、十六烷和甲苯作为油相。结果表明:对于油/水两相体系,在短时间内分离可达到平衡,形成一个明显的油/水界面;在表面活性剂存在情况下,油/水界面的分离时间随其浓度的增加逐渐增大,达到平衡时十二烷基苯磺酸钠异构体会在界面处形成一个明显的界面膜,并对油/水界面处的水分子有限制作用;同时,研究发现十二烷基苯磺酸钠异构体在油水界面处并不是以亲水基伸入水相、疏水基伸入油相的形式垂直排布的,而是以一定的角度"平躺"于油水界面,且以十二烷作为油相时,十二烷基苯磺酸钠异构体在界面排布的密度最大,吸附于界面的趋势最强,与实验结果相符。分子动力学模拟方法可作为实验一种补充,为实验提供必要的微观分子结构信息。更多还原

【Abstract】 By the way of molecular dynamics(MD) simulations,we used GROMACS software simulated(1、3、5)-phenyl dodecyl sulfonate perform between the oil/water phase at the molecular lever,investigated the demixing process of the system,i.e.,oil,water,and an anionic surfactant from the initial"homogeneous phase"to"two separated phases",and studied the effect and roles what different surfactant molecular structure(the aromatic-ring at 1,3,5),concentration, oil phase acted in the process of interface separating.We used improved gromos96 as the force field,SPC as the water model,chloroform,octane,decane,dodecane,detradecane,hexadecane and toluene as the oil phase.The simulations results showed that:the two oil/water phases reached equilibrium in a short simulation time and an evident oil/water interface was formed.In the presence of surfactant molecular,the separation time of oil and water gradually increased as the concentration of surfactant increased and formed an evident interface membrane when the system reached equilibrium.At the same time,it showed that the surfactant hadn’t an vertical distribution as the hydrophilic groups in the water and the hydrophobic groups in the oil,but"flated"by an certain angle in the oil/water phase,when we had the dodecane as the oil, surfactant had the biggest interface distribution density and the trend of absorbed to the interface, which were consistent with the experimental results.The simulations showed that:the MD method can be used as an adjunct and can provide the necessary information for experiments on the microstructural properties of molecular structures.更多还原