亚砜类非离子型表面活性剂在固/液界面上的吸附——Ⅰ.硅胶/水溶液界面上的吸附

Adsorption of Sulfoxides on Solid from Aqueous Solutions——Ⅰ.The Adsorption on Silica

表面活性剂在固/液界面上的吸附在多种应用中起重要作用[1],因而引起了广泛的兴趣.就已有的工作来看,对非离子型表面活性剂在固/液界面吸附的研究比对离子型表面活性剂所作的同类研究要少.

Adsorptions of decyl-and octyl-methylsulfoxide at silica/aq,solution interface andcontact angles of the solutions on quartz have been measured.Effects of temperatureand pH value on the adsorptions have been investigated.The adsorption isotherms areof L4 type on Giles’classification.The average molecular areas in saturated adsorptionlayer are 27—30A~2.The curves ofГ/Гm-C/cmc for the two homologs overlap each other.The temperature coefficients of adsorption negative in the range of low concent-ration and positive in that of high concentration,pH Value has influence onthe adsorption:the lower the pH,the higher the adsorption.Contact anglesmeasurement shows that the adsorption makes the surface of silica gel hydrophobic.Basedon experimental results,it is considered that the adsorption process consists of twostages.One is in the low concentration range by the interaction between solid surfaceand sulfoxide group,another is in the range of high concentration by hydrophobioeffect of surfactant molecules adsorbed and those in solution.