Kinetics of the acid-catalysed hydrolysis of dodecylsulphate and dodecyldiethoxysulphate surfactants in concentrated micellar solutions. Part 1.—Effects of acid and surfactant concentrations and of the nature and concentration of counterions
作者:Christopher J. Garnett、Alan J. Lambie、William H. Beck、Milica Liler
DOI:10.1039/f19837900953
日期:——
The rates of the acid-catalysed hydrolysis of sodium dodecylsulphate (SDS) and sodium dodecyldiethoxysulphate (SDE2S) have been investigated in concentrated surfactant solutions (0.035–0.6 mol dm–3). The acid concentration dependence of the initial rates shows a ‘saturation’ effect, whereas increasing surfactant concentrations above the c.m.c. lead to a maximum in the k2, obs values, beyond which they
在浓缩的表面活性剂溶液(0.035–0.6 mol dm –3)中研究了酸催化十二烷基硫酸钠(SDS)和十二烷基二乙氧基硫酸钠(SDE 2 S)水解的速率。初始速率的酸浓度依赖性显示出“饱和”效应,而高于cmc的表面活性剂浓度增加会导致k 2,obs值最大,超过此值它们会急剧下降。根据胶束反应的离子交换假相模型讨论了这些结果。抗衡离子的性质会影响k 2,obs,其值遵循序列NH 4 > Li> Na镁 这归因于具有氢离子的胶束的斯特恩层中这些阳离子的离子交换常数K H / X的差异。保持总抗衡离子浓度和表面活性剂抗衡离子浓度与氢离子浓度之比恒定(为30,即0.6:0.02 mol dm –3),很大程度上消除了k 2,obs随表面活性剂浓度增加而降低的趋势,因为可以从伪相离子交换模型中获得。但是,理论和实验之间的定量一致性不太好,这至少部分是由于在高离子强度溶液中偏离理想状态的缘故。