系列烷基苯磺酸盐对烷烃的动态界面张力研究

从表面活性剂分子量、表面活性剂浓度、电解质浓度、烷烃碳数等方面考察了系列烷基苯磺酸盐异构体纯化合物的油水动态界面张力行为.研究表明,表面活性剂分子量增大和电解质浓度增加使界面张力动态变化减慢,达到平衡所需时间延长;表面活性剂浓度增加和烷烃碳数增加使界面张力动态变化加快,达到平衡所需时间减少.     

表面活性剂与油相动态界面张力影响因素研究

对不同类型表面活性剂烷基糖苷(APG1214)、咪唑啉(IAS)、十二烷基苯磺酸钠(SDBS)、烷基酚醚羧酸盐(ss-231)的油水动态界面张力进行了研究。在60℃,5 000 r·min-1条件下,考察了表面活性剂的浓度、表面活性剂的结构、正构烷烃碳数以及原油中活性物质对形成低界面张力影响。实验结果表明:表面活性剂亲水基的亲水性越强,亲水基之间排斥力越小,使得在油水界面排布的密度越大,降低界面张力的效果会更好;当表面活性剂疏水碳链与烷烃碳链相似时,降低界面张力的效果会更明显;无碱体系中原油中的活性物质可在油水界面上形成粘弹性界面膜,这种界面膜的形成减少了表面活性剂分子在界面的吸附,使界面张力升高。     

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)

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.     

CMC系列高分子表面活性剂与原油超低界面张力形成机理的研究

采用动态激光光散射及环境扫描电镜研究了羧甲基纤维素系列高分子表面活性剂与大庆原油形成超低界面张力的机理.结果表明,CMC系列高分子表面活性剂具有与低分子量表面活性剂相比拟的表/界面活性,其水溶液的表面张力可达2835mN/m,界面张力达到10^-110mN/m.碱的加入可显著降低高分子表面活性剂与原油的界面张力,在适当条件下界面张力达到超低值(10^-3mN/m),可望作为三次采油的驱油剂.等效烷烃模型研究表明,用碱与原油酸性组分的作用来解释碱能使界面张力下降至超低值的传统观点是不完善的,加入碱能使高分子表面活性剂胶束解缔,胶束数量增多,胶束粒径减小,单分子自由链增加,有利于高分子表面活性剂向界面迁移和排布,这是高分子表面活性剂和碱复配体系与原油界面张力下降至超低值的主要原因.     

疏水缔合聚丙烯酰胺与双子表面活性剂的相互作用

制备了一种脂肪酸酯双磺酸盐型双子表面活性剂, 利用粘度法、界面张力法和原子力显微镜研究了疏水缔合聚丙烯酰胺与双子表面活性剂在溶液中的相互作用. 实验结果表明: 疏水缔合聚丙烯酰胺在溶液中能够通过自组装形成疏水微区并发展成网络结构, 疏水微区与表面活性剂在溶液中能形成混合胶束; 当一定量的表面活性剂加入时, 对疏水缔合聚丙烯酰胺的自组装起促进作用, 而过多双子表面活性剂的加入又会对聚合物分子的自组装起抑制作用, 从而显著影响疏水缔合聚丙烯酰胺的溶液性质, 随着表面活性剂浓度的增加, 聚合物溶液粘度先增加、再降低; 同时, 疏水缔合聚丙烯酰胺对双子表面活性剂的界面性能也有较大影响, 聚合物的加入使双子表面活性剂降低油/水界面张力的能力下降, 油/水界面张力达到平衡所需时间延长.     

不同体系中油酸甲酯与烷基苯磺酸盐协同效应研究

研究了表面活性剂/盐/模拟油体系与表面活性剂/碱/模拟油体系中油酸甲酯与表面活性剂协同效应机理.结果表明两种体系中协同效应机理不同.在盐体系中,油酸甲酯主要通过改变油相的等效烷烃碳数(EACN) 影响表面活性剂在油水相分配.而碱体系中,油酸甲酯影响表面活性剂在油水相分配从而影响界面张力；另一方面,油酸甲酯吸附在界面上顶替表面活性剂分子影响界面张力.对于不同结构表面活性剂,两种作用竞争的结果不同.     

支化十六烷基甲苯磺酸钠的油水界面张力

研究了自制的3种十六烷基甲苯磺酸钠,在正构烷烃/水体系的界面性能. 分别考察了磺酸盐脂肪链支化程度及浓度等以及外加助剂脂肪醇类型和无机盐浓度对磺酸盐最小烷烃碳数nmin和界面张力值的影响. 结果表明,磺酸盐支化程度增加,其nmin变大,最低界面张力值变小;随着磺酸盐浓度的增加,界面张力值先下降后上升;随着助剂脂肪醇碳链长度的增加,其nmin逐渐变大;无机盐的影响则表现为随着盐浓度的增加界面张力值先下降后上升,超低界面张力值出现在一个适宜的盐浓度范围内.     

十六烷基甲苯磺酸钠的界面性能研究

用自制的3种十六烷基甲苯磺酸钠,研究了其正构烷烃/水体系的界面性能。分别考察了磺酸盐支化程度及浓度等内部因素以及外加助剂脂肪醇类型和无机盐浓度等外界因素对磺酸盐最小烷烃碳数n_min以及界面张力值的影响。结果表明,磺酸盐支化程度增加,其n_min变大,最低界面张力值变小;而随着磺酸盐浓度的增加,界面张力值先下降后上升;随着助剂脂肪醇碳链长度的增加,其n_min逐渐变大;无机盐的影响则表现为随着盐浓度的增加界面张力值先下降后上升,超低界面张力值出现在一个适宜的盐浓度范围内。     

高盐油藏下两性/阴离子表面活性剂协同获得油水超低界面张力

研究了在高盐油藏中, 利用两性/阴离子表面活性剂的协同效应获得油水超低界面张力的方法. 两性表面活性剂十六烷基磺基甜菜碱与高盐矿化水具有很好的相容性, 但在表面活性剂浓度为0.07%-0.39%(质量分数)范围内仅能使油水界面张力达到10^-2 mN·m^-1量级, 加入阴离子表面活性剂十二烷基硫酸钠后则可与原油达到超低界面张力. 通过探讨表面活性剂总浓度、金属离子浓度、复配比例对油水动态界面张力的影响, 发现两性/阴离子表面活性剂混合体系可以在高矿化度、低浓度和0.04%-0.37%的宽浓度范围下获得10^-5 mN·m^-1量级的超低界面张力, 并分析了两性/阴离子表面活性剂间协同获得超低界面张力的机制.     

新型磺基甜菜碱/聚丙烯酰胺体系表面及界面性能

采用自制的新型磺基甜菜碱两性表面活性剂与相对分子质量2500万的聚丙烯酰胺进行复配,考察了不同温度和矿化度条件下,聚合物对复配溶液表面、界面性能的影响。 采用滴体积法测定了溶液的表面张力,结果表明,加入聚合物使溶液的临界胶束浓度增大,且复配溶液的表面张力大于单独表面活性剂溶液的表面张力。 当聚合物浓度一定,增大溶液矿化度时,体系表面张力增大。 用旋滴型界面张力仪测定了溶液的界面张力,结果表明,增大聚合物浓度,油水界面张力增大,增大溶液矿化度,油水界面张力有所升高。 聚合物质量浓度为1.5 g/L,表面活性剂质量浓度为0.3 g/L时,可使胜利油田孤岛原油和孤东原油的油水界面张力达到超低数量级（10-3 mN/m）。 用分水时间法测定了溶液的乳化性能,结果表明,聚合物浓度增大,分水时间延长,并考察了75、85和95 ℃条件下体系的乳化性能,温度越高,分水时间越短。     

Studies of synergism/antagonism for lowering dynamic interfacial tensions in surfactant/alkali/acidic oil systems, part 2: synergism/antagonism in binary surfactant mixtures

Experimental studies are conducted in order to elucidate the mechanisms responsible for synergism/antagonism for lowering dynamic interfacial tension in hydrocarbons/binary surfactant mixtures/brine systems. The dynamic interfacial tensions between hydrocarbons of different alkane carbon numbers (from 6 to 14) and solutions of binary surfactant mixtures were measured. We found that the synergism/antagonism for interfacial tension reduction in binary surfactant mixtures having low interfacial tension values was influenced by the alkane carbon number of oil phase, hydrophilic-lipophilic ability of surfactant, and NaCl concentration. A new explanation in view of interactions among surfactant molecules, oil molecules, and water molecules is provided.     

Formulating Middle Phase Microemulsions Using Extended Anionic Surfactant Combined with Cationic Hydrotrope

The phase behavior of systems containing sodium alkyl polypropylene oxide sulfate with equimolar ratio of polypropylene oxide ammonium chloride was determined as a function of salt concentration and alkane carbon number at ambient temperature. Visual inspection as well as cross polarizers were used to detect anisotropy. Solubilization ratios for oil and brine in the middle phases were measured and used to calculate the interfacial tension (IFT) between the microemulsion and oil or brine. The fish diagram is presented showing a minimum amount of 0.20 wt% surfactant needed to form the middle phase. Swelling increases with decreasing the alkane carbon number of the oil. Ultra low IFT values were predicted for the systems investigated.     

Microemulsion Phase Behavior of Aerosol-OT Combined with a Cationic Hydrotrope in the Dilute Region

The phase behavior of systems containing minimum amounts of sodium bis (2-ethylhexyl) sulfosuccinate with equimolar ratio of tetra ethyl ammonium chloride were studied as a function of salt concentration and alkane carbon number at ambient temperature. Visual inspection as well as cross polarizers were used to detect anisotropy. Solubilization ratios for oil and brine in the middle phases were measured and used to calculate the interfacial tension. Ultra-low interfacial tension values were predicted for the systems containing heptane, octane and nonane as model oil. Different phase behavior was observed for systems with higher alkane number.     

Effect of Molecular Weight on the Interfacial Dilational Viscoelasticity of Anionic Polyelectrolyte/Surfactant Systems

In this article, the effect of molecular weight on the interfacial tension and interfacial dilational viscoelasticity of polystyrene sulfonate/surfactant adsorption films at the water-octane interface have been studied by spinning drop method and oscillating barriers method respectively. The experimental results show that different interfacial behaviors can be observed in different type of polyelectrolyte/surfactant systems. PSS/cationic surfactant CTAB systems show the classical behavior of oppositely charged polyelectrolyte/surfactant systems and can be well explained by electrostatic interaction. Molecular weight of PSS plays a crucial role in the nature of adsorption film. The complex formed by CTAB and higher molecular weight PSS, which has larger dimension and stronger interaction, results in higher dilational modulus at lower surfactant bulk concentration. In the case of PSS/anionic surfactant SDS systems, the co-adsorption of PSS at interface through hydrophobic interaction with alkyl chain of SDS leads to the increase of interfacial tension and the decrease of dilational modulus at lower surfactant bulk concentration. For PSS/nonionic surfactant T × 100 systems, PSS may form a sublayer contiguous to the aqueous phase, which has little effect on interfacial tension but slightly decreases dilational modulus.     

Studies of synergism/antagonism for lowering dynamic interfacial tensions in surfactant/alkali/acidic oil systems. 1. Synergism/Antagonism in surfactant/model oil systems

Experimental studies are conducted in order to elucidate the mechanisms responsible for synergism/antagonism for lowering dynamic interfacial tension in model oil/surfactant/brine systems. A well-defined model oil is selected for controlled design of experiments, thus enhancing verification of known and unknown mechanisms. The systems examined contain model oils and two petroleum sulfonate solutions. The influence of additives in oil phase, such as carboxylic acids with different chain length, n-octadecanol, and oil soluble surfactant SP-60, on the equivalent alkane carbon number (EACN) values has been examined. The interfacial tensions of different model oils with different EACN values against surfactant solutions with different n(min) values have also been obtained. We find that antagonism has been observed when EACN/n(min) value is far from unity by adding organic components, while synergism has been observed when EACN/n(min) value is close to unity. The results present here suggest that organic additives in oil phase controlled interfacial tension by changing the partition of surfactants in oil phase, aqueous phase, and interface.     

Competitive adsorption of surfactants and hydrophilic silica particles at the oil-water interface: interfacial tension and contact angle studies

The effect of surfactants' type and concentration on the interfacial tension and contact angle in the presence of hydrophilic silica particles was investigated. Silica particles have been shown to have an antagonistic effect on interfacial tension and contact angle in the presence of both W/O and O/W surfactants. Silica particles, combined with W/O surfactant, have no effect on interfacial tension, which is only dictated by the surfactant concentration, while they strongly affect interfacial tension when combined with O/W surfactants. At low O/W surfactant, both particles and surfactant are adsorbed at the interface, modifying the interface structure. At higher concentration, interfacial tension is only dictated by the surfactant. By increasing the surfactant concentration, the contact angle that a drop of aqueous phase assumes on a glass substrate placed in oil media decreases or increases depending on whether the surfactant is of W/O or O/W type, respectively. This is due to the modification of the wettability of the glass by the oil or water induced by the surfactants. Regardless of the surfactant's type, the contact angle profile was dictated by both particles and surfactant at low surfactant concentration, whereas it is dictated by the surfactant only at high concentration.     

石油磺酸盐体系中相微乳液研究

宽分子量分布的石油磺酸盐在低浓度时有正丁醇、正构烷烃、盐存在的情况下能成中相微乳液。研究了盐浓度、烷烃种类、醇浓度对该体系中相微乳液的形成及特性影响,得到中相微乳液的特性参数;最佳含盐量Ｓ＾＊、增溶参数σ、盐宽△Ｓ、界面张力γ等,并从理论上进行了探讨。采用模拟驱油装置测定了体系的驱油效率,对优化驱油体系设计具有重要意义。     

Effect of interfacial tension on the dynamic behavior of droplet formation during microchannel emulsification

Microchannel (MC) emulsification is a novel technique for producing monodisperse emulsions. In this study, we investigated the effect of interfacial tension on the dynamic behavior of droplet formation with various surfactant concentrations. Interfacial tension did not affect the resultant droplet diameter in lower flow velocity ranges, but it did affect the time-scale parameters. These results were interpreted using the droplet formation mechanism reported in our previous study. At surfactant concentrations below 0.3%, the emulsification behavior was differed from that at higher surfactant concentrations. An analysis of diffusional transfer indicated that dynamic interfacial tension affects the emulsification behavior at lower surfactant concentrations. Dynamic interfacial tension that exceeded the equilibrium value led to a shorter detachment time. This resulted in stable droplet formation of monodispersed emulsions by spontaneous transformation, even at flow velocities above the predicted critical flow velocity. A previous study predicted that the droplet formation would become unstable and polydispersed larger droplets would form over critical flow velocity. Wetting of the MC with the dispersed phase at lower surfactant concentrations induced formation of larger polydispersed droplets at high flow velocities.