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本文研究了具有双烃链的正、负离子表面活性剂混合水溶液的表面和液相性质。负离子表面活性剂是琥珀酸二己酯磺酸钠[简写为(C_6)_2SNa],正离子表面活性剂是氯化二正辛基羟乙基甲基铵[(C_8)_2NCl]和氯化辛基羟乙基二甲基铵[C_8NCl]。为了增加复合物的溶解度,在铵基上引入了羟乙基。测定了表面张力-浓度关系,用Gibbs公式计算了表面吸附量和吸附分子面积。结果表明,由于正、负表面活性离子之间的强烈相互作用,所研究的两种混合物体系的表面活性远高于单独的表面活性剂。在等摩尔混合和离子强度0.1mol/kg情况下,(C_6)_2SNa-(C_8)_2NCl体系的吸附层组成是对称的(摩尔比为1∶1),且在临界胶团浓度(cmc)以上析出新相,表明此cmc实质上是复合物的溶解度;而(C_6)_2SNa-C_8NCl体系的吸附层为不对称组成(摩尔比非1∶1),在cmc以上可能形成相当大的胶团。两种体系混合溶液的起泡性有极大差异。
In this paper, the surface and liquid phase properties of a mixed aqueous solution of double and double hydrocarbon chains were studied. The anionic surfactant is dihexyl sodium succinate [abbreviation (C_6) _2SNa], the cationic surfactant is di-n-octyl hydroxyethyl methyl ammonium chloride [(C_8) _2NCl] and chlorinated symplectic Hydroxyethyl dimethyl ammonium [C_8NCl]. In order to increase the solubility of the complex, a hydroxyethyl group is introduced on the ammonium group. The relationship between surface tension and concentration was determined. The Gibbs formula was used to calculate the surface adsorption and the area of adsorbed molecules. The results show that due to the strong interaction between the positive and negative surface-active ions, the surface activity of the two mixture systems studied is much higher than that of the surfactant alone. The adsorption layer composition of (C_6) _2SNa- (C_8) _2NCl system is symmetrical (molar ratio is 1: 1) under the conditions of equimolar mixing and ionic strength of 0.1 mol / kg and above the critical micelle concentration The new phase was precipitated, indicating that this cmc is essentially the solubility of the complex. However, the adsorption layer of (C_6) _2SNa-C_8NCl system is asymmetric (molar ratio is not 1: 1), and considerable micelles may form above cmc. There is a great difference in the foaming between the two systems.