The membrane–solution interface under high-performance current regimes of electrodialysis by means of laser interferometry

Abstract

Application of laser interferometry allowed visualization of the process of formation and development of the diffusion layers during electrodialysis in a wide range of current densities. In the range of current in a solution at the boundary with a cation-exchange membrane the values corresponding to a second inflection point at I–V curve convection instability can be seen simultaneously with fluctuations of the potential. With an increase of the current density the area of the solution involved in convection intermixing grows, and there appears a non-steady vibrational concentration profile with the maximum amplitude of vibrations near the cation-exchange membrane. It has been experimentally found, using laser interferometry, that this effect reveals itself less clearly for an anion-exchange membrane MA-40.