In electrochemical systems, the direct current densities not exceeding the limiting current density are applied.
Two of them are associated with water splitting.
Did you know that the recent practice of electrodialysis evidences the interest of other current modes where either the imposed direct current is over the limiting one or a ‘non constant’ asymmetrical current is used. These effects result from formation of concentration gradients caused by the current flowing under conditions where ionic transport numbers are different in the membrane and solution. It is shown that the intensive current modes are compatible with new trends in water treatment oriented towards Zero Liquid Discharge technologies. The relation of these effects to the properties of the membrane surface is analyzed. The interaction between the coupled effects is studied, and the conditions under which one or another effect becomes dominant are discussed.
Two others are due to coupled convection partially destroying the diffusion boundary layer.
Four effects providing overlimiting current conductance are examined.
The application of intensive current modes in electrodialysis, the ‘stateoftheart’ and perspectives, are considered. In electrode ones, in electrophoresis and electrokinetic ‘microand’ nanofluidic devices similar to micropumps, similar effects take place not only in electrodialysis membrane systems. For instance, the theoretical background for mathematical modelling of mass transfer at overlimiting currents is described. The paper is devoted to make the mechanisms of mass transfer under these current regimes more clear.