C_9 FK的表面活性测定

Surface Activity of C_9FK

用吊片法和自制改进的最大泡压法分别测定了全氟庚氧基全氟亚乙基磺酸钾(C9FK)溶液的平衡和动态表面张力,计算得出该种表面活性剂形成胶束的标准热力学函数△Hmθ、△Smθ、△Gmθ分别为16．98 kJ／mol、218．29 J／mol·K、-48．22 kJ／mol。结合Word-Tordai方程,计算得到在不同条件下的表观扩散系数Da和吸附势垒Ea。实验证明,增大表面活性剂的浓度、降低温度、以及无机盐(NaCl)的加入都会使扩散系数减小,吸附势垒增大,从而不利于吸附的进行。当表面活性剂的浓度小于等于1×10-6 mol/L时,该体系属于扩散控制模型,而浓度大于 1×10-6 mol/L时,在吸附初期(t→O)属于扩散控制,后期均属于混合控制模型。

The equilibrium and dynamic surface tensions of C9FK were measured by Wilhelmy plate and a modern maximum bubble pressure method ( MBPM), respectively, and the standard thermodynamical functions △Hmθ, △Smθ and △Gmθ were calculated as 16. 98 kJ/mol,218. 29 J/mol· K and -48. 22 kJ/mol respectively. Increase of concentration of the surfactant, decrease of temperature or addition of salts (NaCl) will reduce the apparent diffusion coefficients and raise the adsorption barriers. The adsorption process is controlled by a diffusion step at low surfactant concentration ( c ≤1×10-6 mol/L). When c>1 ×10-6 mol/L, the adsorption process is controlled by a diffusion step at the beginning, and then changes to a mixed kinetic-diffusion adsorption step.