Influence of spacers on mass transport in electromembrane desalination systems

Abstract

Abstract In electromembrane desalination systems, ion transport near ion exchange membranes induces inevitable concentration polarization, which complicates mass transport. To mitigate the effect of concentration polarization and increase mass transport, spacers which promote mixing and change the flow velocity distribution in the channel. The authors investigated the effect of several spacers (from one to three) on the electromembrane system and varied the size and shape of the spacers, distance to the membranes and flow rate. It has been shown that the presence of spacers actually makes it possible to redistribute the speed and direction of the flow in the system and to increase the current efficiency. The article analyzes the impact of the spacers in the distant exorbitant conditions on mass transport and electroconvective vortices. In the article, we calculated and compared the current-voltage characteristics in the ohmic region, the “plateau” region and overlimiting region for channels with and without spacers. The work investigates fundamental laws depending on the location, size and number of spacers. This paper investigates the effect of non-conductive spacers. It has been shown that, for example, the presence of several spacers (three) near the center of the channel, slightly shifted towards the anion-exchange membrane, increases the mass transport by about 24% -25%. In addition, the influence of spacers on the emergence and development of electroconvective vortices has been studied.