包裹体(矿物)
扩散
扩散方程
热力学
有效扩散系数
化学
矿物学
材料科学
物理
经济
放射科
服务(商务)
医学
磁共振成像
经济
作者
Semyon Mareev,D. Yu. Butylskii,Anna Kovalenko,Natalia Pismenskaya,L. Dammak,C. Larchet,Victor Nikonenko
标识
DOI:10.1134/s1023193516100098
摘要
The applications of the Sand equation in potentiometry of electrode and membrane systems for precise measurements of the transition time (τ) have been determined. An approach was suggested for choosing the diffusion coefficient of electrolyte (D) in the case when the concentration changes from its value in the agitated solution (where D = D b) to the nearly zero value at the surface (D = D 0 corresponds to an infinitely dilute solution), D b and D 0 being substantially different. The Nernst–Planck–Poisson nonstationary equations were numerically solved in a one-dimensional system including an ion-exchange membrane and two adjacent diffusion layers (for the electrode–solution system, the result is a particular case). An effective value D ef was found, whose substitution in the Sand equation gave τ identical to that obtained by numerical solution. The neglect of the concentration dependence D(с) can lead to a nonadequate determination of the ion transport numbers in the membrane.
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