共查询到18条相似文献,搜索用时 359 毫秒
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采用分子动力学模拟研究了以十二烷基苯磺酸钠(SDBS)为代表的阴离子型表面活性剂,以十二烷基三甲基溴化铵(DTAB)为代表的阳离子型表面活性剂,以壬基酚聚氧乙烯醚(NPE)为代表的非离子型表面活性剂,以十二烷基二甲基甜菜碱(Betaine)为代表的两性表面活性剂及空白实验.模拟了表面活性剂在油水界面上的行为,考察了表面活性剂分子与石油分子之间的径向分布函数(RDF)、石油分子在竖直方向的均方位移(MSD)、油水界面张力(IFT)、石油层与岩石层之间的相互作用能、石油层的相对浓度在竖直方向的分布及石油分子质心位置随模拟时间的变化关系等,讨论了不同表面活性剂的洗油性能.结果表明:(1)SDBS,NPE和Betaine分子初始状态下呈近似的规律排列,非极性端部分插入油相中,极性端延伸进入水相中;随后表面活性剂的极性端表现出聚集趋势,逐渐形成一个外部亲油内部亲水的一个胶束状粒子,粒子随模拟的进行逐渐融入到油层当中;DTAB从开始的近似规则排列逐渐变为无规排列,但是始终保持亲油端插入到油相中,亲水端位于油水界面上.(2)表面活性剂分子与石油分子之间的相互作用强弱顺序为Betaine≈DTABSDBSNPE.(3)由质心高度和动力过程中的图像截图分析,表面活性剂洗油效果的顺序为BetaineSDBSNPEDTABNone.模拟结果与实际的驱油结果一致,从分子层面上解释了不同表面活性剂洗油的规律. 相似文献
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油/水界面表面活性剂的复配协同机制 总被引:3,自引:0,他引:3
采用耗散颗粒动力学(DPD)方法模拟了椰油酸二乙醇酰胺(6501)分别与十二烷基-α-烯烃磺酸钠(DAOS)、椰油酰胺丙基二甲基甜菜碱(CAB)和十二烷基苯磺酸钠(SDBS)复配体系中表面活性剂在油/水界面的排布行为, 探讨了盐度及分子结构对单一和复配表面活性剂界面活性的影响, 从界面效率、界面密度和分子排布等角度讨论了油水界面表面活性剂混合体系的复配协同增效机制. 相似文献
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采用耗散颗粒动力学(DPD)模拟方法在介观层次上模拟了表面活性剂十六烷基三甲基溴化铵(CTAB)在油/水界面的自组装行为,考察了表面活性剂浓度、油水比例以及剪切力等环境因素对表面活性剂界面张力、尾-尾间距离及油水界面厚度的影响。结果发现,油水比例增大可显著降低CTAB存在的油水界面张力,提高CTAB的界面活性;有剪切存在时,表面活性剂在界面的聚集行为明显改变,分子在界面处的排列变得混乱,有序性降低,导致尾-尾间距离减小、界面厚度增加,界面效率显著降低。模拟表明,介观模拟方法可以作为实验的一种补充,为实验提供必要的微观分子结构信息。 相似文献
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阴离子表面活性剂在水/正烷烃界面的分子动力学模拟(英文) 总被引:1,自引:0,他引:1
利用分子动力学模拟方法研究了阴离子表面活性剂在水/正烷烃(壬烷,癸烷和十一碳烷)界面的结构和动力学特点.十六烷基苯磺酸钠作为研究对象,其中苯磺酸基团在十六碳烷的第4号碳原子上,记作4-C16.分析了不同油相和特定盐度条件下正烷烃-表面活性剂-水体系的界面特点(如密度剖面图、界面张力和径向分布函数).模拟结果表明平衡模型体系展现了一个很好的水/正烷烃界面.当加氯化钠到水溶液中,正烷烃-表面活性剂-水体系的界面张力有微小的变化,有趣的是表面活性剂二面角的反式结构分数的变化联系着界面张力的微小变化.可见,表面活性剂在界面处的结构对降低界面张力起到重要的作用.此外,还发现表面活性剂的极性头与钠离子和水分子存在较强的相互作用. 相似文献
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驱油表面活性剂的分子设计是一项重要的研究课题.设计新型高效的驱油表面活性剂关键的问题在于如何洞察表面活性剂的结构和功能的关系.长线性烷基苯磺酸盐是一类非常流行的表面活性剂,广泛应用于工业和日常生活中.关于烷基苯磺酸盐的结构和功能研究已有大量的实验和理论工作报道.近来,结合分子设计的思想,实验上合成了新型的羟基取代的烷基苯磺酸盐表面活性剂,并研究了这类新型表面活性剂动态的界面行为.我们从理论上利用分子动力学模拟的方法研究了羟基取代的烷基苯磺酸盐单分子层在水/气和水/癸烷界面的结构特点.从液体密度剖面图、氢键、表面活性剂聚集结构和有序参数等方面,详细报道了2-羟基-3-癸基-5-辛基苯磺酸钠这种新型阴离子表面活性剂的界面特征.模拟结果表明随着表面活性剂分子数目的增加,每个表面活性剂在单分子层上形成分子内氢键的平均数目将下降,但形成分子内氢键的结构仍处于主导地位;烷基尾链的疏水部分,尤其是苯环3号位上取代的癸基随着表面活性剂覆盖度增大,向界面外延伸并且更加有序;二维径向分布函数描绘了表面活性剂聚集结构的特点并暗示了癸烷相将影响表面活性剂疏水部分的取向;表面活性剂分子容易形成长程氢键结构.我们的模拟结果是对实验研究的一个重要补充.此外,模拟中我们利用gromacs和ffamber程序,使用了全原子模型,这将为模拟烷基苯磺酸盐表面活性剂的界面行为提供新的方案. 相似文献
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利用Langmuir槽法研究了含聚氧乙烯醚链中间链的两性Gemini表面活性剂C8E4NC12、阳离子Gemini表面活性剂C12NE3NC12和阴离子Gemini表面活性剂C8E4C8在空气/水表面和癸烷/水界面上的扩张性质,考察浓度对3种Gemini表面活性剂溶液表、界面扩张性质的影响.结果表明,由于分子间存在库仑引力,两性Gemini分子表现出较高的扩张弹性和粘性,且界面扩张性质类似于表面.对于有相同电荷Gemini分子,C8E4C8分子中的刚性苯环导致其疏水长链在表面上的取向不同于C12NE3NC12分子,两者表现出不同的表面扩张性质;而油分子能改变同电荷Gemini分子中长链烷基的取向,造成其界面扩张弹性和粘性远低于表面.提出了不同电性Gemini分子在界面排布的示意图,并利用弛豫过程的特征参数进行了验证. 相似文献
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Significant synergistic effects between sodium dodecylbenzene sulfonate (SDBS) and nonionic nonylphenol polyethylene oxyether, Triton X-100 (TX-100), at the oil/water interface have been investigated by experimental methods and computer simulation. The influences of surfactant concentration, salinity, and the ratio of the two surfactants on the interfacial tension were investigated by conventional interfacial tension methods. A dissipative particle dynamics (DPD) method was used to simulate the adsorption properties of SDBS and TX-100 at the oil/water interface. The experiment and simulation results indicate that ultralow (lower than 10(-3) mN m(-1)) interfacial tension can be obtained at high salinity and very low surfactant concentration. Different distributions of surfactants in the interface and the bulk solution corresponding to the change of salinity have been demonstrated by simulation. Also by computer simulation, we have observed that either SDBS or TX-100 is not distributed uniformly over the interface. Rather, the interfacial layer contains large cavities between SDBS clusters filled with TX-100 clusters. This inhomogeneous distribution helps to enhancing our understanding of the synergistic interaction of the different surfactants. The simulation conclusions are consistent with the experimental results. 相似文献
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The array and interfacial activity of sodium dodecyl benzene sulfonate and sodium oleate at the oil/water interface 总被引:2,自引:0,他引:2
Li Y Zhang P Dong FL Cao XL Song XW Cui XH 《Journal of colloid and interface science》2005,290(1):275-280
There is a close correlation between the interfacial activity and the adsorption of the surfactant at the interface, but the detailed molecular standard information was scarce. The interfacial activity of two traditional anionic surfactants sodium dodecyl benzene sulfonate (SDBS) and sodium oleate (OAS) were studied by experimental and computer simulation methods. With the spinning drop method and the suspension drop method, the interfacial tension of oil/aqueous surfactant systems was measured, and the influence of surfactant concentration and salinity on the interfacial tension was investigated. The dissipative particle dynamics (DPD) method was used to simulate the adsorption of SDBS and OAS at the oil/water interface. It was shown that it is beneficial to decrease interfacial tension if the hydrophobic chains of the surfactant and the oil have similar structure. The accession of inorganic salts causes surfactant molecules to form more compact and ordered arrangements and helps to decrease the interfacial tension. There is an osculation relation between interfacial density and interfacial activity. The interfacial density calculated by molecular simulation is an effective parameter to exhibit the interfacial activity. 相似文献
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Feng Li Wenxi Zhu Hua Song Keliang Wang Wei Li 《Journal of Dispersion Science and Technology》2018,39(10):1524-1531
A novel ternary sulfonated polyacrylamide was synthesized using 2,2′-azobis[2- methylpropionamidine] dihydrochloride and redox initiation system as initiator, respectively. The competitive adsorption of the ternary sulfonated polyacrylamide (TSPAM) and sodium dodecyl benzene sulfonate (SDBS) on the oil-water interface was investigated by equilibrium interfacial tension, interfacial viscoelasticity, zeta potendial and interfacial film strength. The SDBS molecules in the surfactant-polymer (SP) system preferentially adsorb on the oil-water interface due to the amphiphilic structure of the SDBS molecules. Electrostatic force between the charged groups of the polyacrylamide and the head groups of surfactant adsorbed on the interface in the SP system leads to the formation of the complex interface film, which is helpful to enhance the stability of the oil-water interface. The ternary sulfonated polyacrylamide (TSPAM) has a similar influence on the other interface properties with SDBS except the interfacial tension. The interfacial tension decreases and then increases with increasing of the TSPAM concentration due to the competitive adsorption of the TSPAM molecules and the SDBS molecules on the oil-water interface. Moreover, TSPAM has the more influence on the stability of oil-water interface than partially hydrolyzed polyacrylamide (HPAM) in the SP system, and the addition of TSPAM is better to improve the stability of emulsion in the SP flooding. 相似文献
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Emulsification at the Liquid/Liquid Interface: Effects of Potential,Electrolytes and Surfactants
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Emulsification of oils at liquid/liquid interfaces is of fundamental importance across a range of applications, including detergency. Adsorption and partitioning of the anionic surface active ions at the interface between two immiscible solutions is known to cause predictable chaos at the transfer potential region of the surfactant. In this work, the phenomenon that leads to the chaotic behaviour shown by sodium dodecylbenzene sulfonate (SDBS) at the water/1,2‐dichloroethane interface is applied to commercial surfactants and aqueous/glyceryl trioleate interface. Electrochemical methods, electrocapillary curves, optical microscopy and conductivity measurements demonstrated that at 1.5 mm of SDBS, surfactants are adsorbed at the interface and assemble into micelles, leading to interfacial instability. As the concentration of the anionic surfactant was enhanced to 8 and 13.4 mm , the Marangoni effect and the interfacial emulsification became more prominent. The chaotic behaviour was found to be dependent on the surfactant concentration and the electrolytes present. 相似文献
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Yefei Wang Xulong Cao Jun Zhang Xinwang Song Mingchen Ding 《Journal of Dispersion Science and Technology》2018,39(8):1178-1184
Various experimental methods were used to investigate interaction between polymer and anionic/nonionic surfactants and mechanisms of enhanced oil recovery by anionic/nonionic surfactants in the present paper. The complex surfactant molecules are adsorbed in the mixed micelles or aggregates formed by the hydrophobic association of hydrophobic groups of polymers, making the surfactant molecules at oil-water interface reduce and the value of interfacial tension between oil and water increase. A dense spatial network structure is formed by the interaction between the mixed aggregates and hydrophobic groups of the polymer molecular chains, making the hydrodynamic volume of the aggregates and the viscosity of the polymer solution increase. Because of the formation of the mixed adsorption layer at oil and water interface by synergistic effect, ultra-low interfacial tension (~2.0?×?10?3 mN/m) can be achieved between the novel surfactant system and the oil samples in this paper. Because of hydrophobic interaction, wettability alteration of oil-wet surface was induced by the adsorption of the surfactant system on the solid surface. Moreover, the studied surfactant system had a certain degree of spontaneous emulsification ability (D50?=?25.04?µm) and was well emulsified with crude oil after the mechanical oscillation (D50?=?4.27?µm). 相似文献
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Experimental studies were conducted to explore the fundamental mechanisms of alkali to lower the interfacial tension of oil/heavy alkylbenzene sulfonates (HABS) system. Sodium hydroxide was used as the strong alkali chemical to investigate the interfacial tension (IFT) of oil/HABS system. The influences of salt and alkali on the interfacial activity were studied by the measurement of interfacial tension and partition coefficient. Moreover, the alkali/surfactant solutions were measured by dynamic laser scattering. The results showed that compared with the salt, the function of alkali to lower the interfacial tension and improve partition coefficient is more significant. The micelles formed by surfactants could be disaggregated because of adding alkali, so the size of micelles decreases and the number of mono‐surfactants increases, then more surfactant molecules move to the interface of oil/surfactant system and the adsorption of surfactants at oil‐water interfaces increases, which can lead to the decrease of IFT. 相似文献
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Thao T. P. Nguyen Dr. Foad Raji Dr. Cuong V. Nguyen Dr. Ngoc N. Nguyen Prof. Anh V. Nguyen 《Chemphyschem》2023,24(23):e202300062
Surfactants are used to control the macroscopic properties of the air-water interface. However, the link between the surfactant molecular structure and the macroscopic properties remains unclear. Using sum-frequency generation spectroscopy and molecular dynamics simulations, two ionic surfactants (dodecyl trimethylammonium bromide, DTAB, and sodium dodecyl sulphate, SDS) with the same carbon chain lengths and charge magnitude (but different signs) of head groups interact and reorient interfacial water molecules differently. DTAB forms a thicker but sparser interfacial layer than SDS. It is due to the deep penetration into the adsorption zone of Br− counterions compared to smaller Na+ ones, and also due to the flip-flop orientation of water molecules. SDS alters two distinctive interfacial water layers into a layer where H+ points to the air, forming strong hydrogen bonding with the sulphate headgroup. In contrast, only weaker dipole-dipole interactions with the DTAB headgroup are formed as they reorient water molecules with H+ point down to the aqueous phase. Hence, with more molecules adsorbed at the interface, SDS builds up a higher interfacial pressure than DTAB, producing lower surface tension and higher foam stability at a similar bulk concentration. Our findings offer improved knowledge for understanding various processes in the industry and nature. 相似文献