Corrugated membrane surfaces for effective ion transport in electrodialysis

Corrugation over membrane surface causes destabilization of diffusion boundary layer and influences ion transport in electrodialysis by reducing thickness of concentration polarization. Mathematical model based on Navier-Stokes, continuity and Nernst-Plank was proposed and simulated using COMSOL. The proposed model was validated with experimental data of (i) corrugated membranes (from literature) and (ii) limiting current density (LCD) values determined in house (deviation was lesser than 4.5%). The shape, dimension and spacing of corrugations (59 -rectangular and 61- right angled triangle) were systematically investigated and compared with commonly used netted spacer to find the best corrugation for ion removal. Rectangular corrugation of specific geometry performed at par with netted spacers but with substantially lower pressure drop in the whole velocity range. Selected dimension of right angle triangle performed better at lower velocities but got less effective at higher velocities.