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采用旋滴法测定了烷基苯磺酸盐Gemini表面活性剂Ia水溶液与正庚烷的界面张力,用超微电极循环伏安法测定了水溶液中Ia的胶束扩散系数。结果发现,NaCl的加入能够使界面张力降低2倍左右,使Ia的胶束扩散系数变大;Ia浓度增大,胶束扩散系数变小,而NaCl浓度增大,胶束扩散系数变大。这些变化说明NaCl的加入使得Ia胶束大小发生了变化。这是由于NaCl的加入降低了Ia离子头基之间的静电斥力,使得Ia分子排列更加紧密,更有效降低了油水的界面张力,使胶束形状变小;同时胶束表面电荷得到中和,胶束的静电斥力相应减小,胶束流动性相应增加,从而表现出较大的胶束扩散系数。
The interfacial tension of alkylbenzene sulfonate Gemini surfactant Ia aqueous solution and n-heptane was measured by spin-drop method. The micellar diffusion coefficient of Ia in aqueous solution was determined by cyclic voltammetry. The results showed that the addition of NaCl can reduce the interfacial tension by about 2 times and make the micellar diffusion coefficient of Ia larger; the concentration of Ia increases, the micelle diffusion coefficient decreases, while the NaCl concentration increases, the micelle diffusion coefficient becomes larger. These changes indicate that the addition of NaCl makes the size of Ia micelles change. This is because the addition of NaCl reduces the electrostatic repulsion between the head groups of Ia ions, making the Ia molecules arranged more closely and effectively reducing the interfacial tension between oil and water, resulting in a smaller micelle shape. At the same time, the surface charge of the micelles is neutralized, The electrostatic repulsion of the micelles decreases correspondingly, and the micellar mobility increases accordingly, which shows a larger micelle diffusion coefficient.