Augmented electroosmotic flow and simultaneous desalination in microchannels embedded with permselective membranes

Ion-selective nanoporous membranes are widely used in many engineering and technological applications, such as biomolecular separation, desalination, sample preconcentration and fuel cells etc. In this paper, we study steady-state electrokinetic flow of electrolytes in a micro-fluidic channel with permselective membranes embedded at the middle of the walls. Distribution of the ion concentrations and the fluid flows at varied cross-membrane voltages are investigated. It is shown that such systems possess the combined advantages of fast flow generated by electroosmosis of the second kind and desalinating functionalities. It is demonstrated that the membrane-embedded microchannel of length 60 μm and width 10 μm may achieve 89% of salt rejection 15 times of classical electroosmotic flow speed under a cross channel field of 40 V/cm and a cross 400 mV membrane voltage. This kind of microfluidic devices could be used in small- or medium- scale desalination plants and microfluidic pump systems.