From small to big: ion transport at interfaces

Ion transport is crucial in many applications such as desalination and fuel cells. This thesis describes fundamental investigations on the effect of temperature and permittivity gradients on ion transport at charge selective interfaces for electrodialysis systems. Numerical and experimental investigations on different length scales were combined to investigate charge transport in the characteristic Ohmic, limiting and overlimiting current regimes of electrodialysis systems. Temperature gradients can enhance the selective transport of ions through changing ionic diffusivity. In systems with permittivity gradients at the charge selective interface, an immediate electro-osmotic flow is induced even in the Ohmic regime. This can greatly enhance ion transport towards the interface, without having to operate in overlimiting current conditions. The results of this work have implications in numerous processes dependent on ion transport phenomena such as fuel cells and desalination and yields fundamental insights into the nature of charge transport.