胶体泡沫(CGA)排液动力学研究

Investigation of the Kinetics of Liquid Drainage from Colloidal Gas Aphrons

分别对三种表面活性剂,十二烷基硫酸钠(SDS)、十六烷基三甲基溴化铵(HTAB)以及吐温80(Tween80)形成的胶体泡沫(CGA)的排液过程动力学进行了研究.讨论了表面活性剂种类和浓度,体系温度等对CGA排液过程的影响.运用非线性最小二乘法拟合,推出了表征CGA排液过程的动力学模型:Vt=Vmaxtn/(Kn+tn),式中,Vt表示时间t时的排液量(mL),t表示排液时间(s),Vmax表示CGA最大排液量(mL)的模型参数,K为模型参数,表征CGA排液过程的半衰期t1/2,n为排液曲线反曲特征指数.通过该模型计算出了表征CGA排液过程的速率常数kd和半衰期t1/2等参数.并通过lnkd～T-1的线性关系,证明了该模型符合Arrhenius方程.最后,通过对CGA排液速率随时间的变化分析,解析了CGA排液过程的“两段论”机理.

The kinetics of liquid drainage from colloidal gas aphrons （CGA） was investigated at various concentrations of sodium dodecyl sulphate （SDS）, hexadecyltrimethyl ammonium bromide （HTAB）, and Tween 80, respectively, under the conditions of different temperatures. The liquid drainage rates were determined by reading the volume of the liquid drained as a function of time. Effect of the surfactant type, concentration and system temperature on the kinetic stability of CGA was discussed. Drainage behavior was fitted by the empirical equation： Vt=Vmax^t^n/（K^n＋t^n）, where Vt refers to the volume of drained liquid at time t, Vmax denotes the maximum volume of drained liquid, n describes the sigmoidal character of the curve and K is equal to the half-life t1/2 of drainage. Rate constant kd and the half-life t1/2 of liquid drainage could be calculated from parameters Vmax, K, and n. This kinetic model was tested with the use of the Arrhenius equation, which relates the logarithm of the kinetic constant （In kd） linearly to the reciprocal of the elevated temperature （T^-1）. Two distinct stages of CGA drainage determined by two independent mechanisms were identified from analysis of the rate of liquid drainage as a function of time.