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本文研究了盐存在时不同比例的十二烷基硫酸钠(简称12CH)和溴化正辛基三甲基铵(简称C_8NBr)混合物的表面活性、表面吸附以及胶团形成等性质。结果表明:(1)正、负离子表面活性剂混合物具有很高的表面活性,不论其混合比例如何,临界胶团浓度(cmc)及cmc时溶液的表面张力(γ_(cmc))皆较任何单一组分时小;(2)不论体相中比例如何,表面层中12CH和C_8NBr的饱和吸附量的摩尔比皆～1.7,且总饱和吸附量亦皆～5.2×10~(-10)mol·cm~(-2)。由此求得表面层中分子截面积为32~2,与由分子结构计算的数据相近,说明正、负表面活性离子排列紧密;(3)与碳链长相同的正、负离子型表面活性剂混合水溶液比较,本体系反离子浓度对cmc有明显影响,证实表面层带电,胶团也带电;(4)计算了离子强度相同、温度不同时和温度相同、离子强度不同时的热力学量,得出离子强度大者易形成胶团。
In this paper, the surface activity, surface adsorption and micelle formation of mixtures of sodium dodecyl sulfate (abbreviated as 12CH) and n-octyltrimethylammonium bromide (abbreviated as C_8NBr) were investigated in the presence of salt. The results showed that: (1) The positive and negative ion surfactant mixtures had higher surface activity than that of any single one, regardless of their mixing ratio, the critical micelle concentration (cmc) and the solution surface tension (cmc) (2) The molar ratio of saturated adsorption of 12CH and C_8NBr in the surface layer is ~ 1.7 and the total adsorption capacity is -5.2 × 10 ~ (-10) mol · cm ~ (-2). Thus, the molecular cross-sectional area of the surface layer is 32 to 2, which is similar to the data calculated from the molecular structure, indicating that the positive and negative surface active ions are arranged closely; (3) the positive and negative ionic surfactants having the same carbon chain length Compared with the mixed aqueous solution, the concentration of the counter ion of the system has a significant effect on the cmc, confirming that the surface layer is charged and the micelles are charged. (4) The thermodynamic quantities obtained when the ionic strength is the same, the temperature is not the same, the temperature is the same, and the ionic strength is different are calculated Out of the ion strength is easy to form micelles.