염도 차 발전 적용을 위한 고농도 고분자전해질이 주입된 나노 채널 멤브레인

Abstract

The efforts in many scientific fields for replacing fossil fuel-based energy generation have been continued to decline further climate changes. Recently, reverse electrodialysis (RED), one of the promising process for generating electrical power from salinity differences between the sea and river water, has drew keen attention as an alternative process for an electrical power production. RED is less vulnerable to external influences such as a weather and the alteration of day with night so that it is capable of producing stable the electrical power production. However, commercially available ion-exchange membranes (IEMs), fundamental elements in a RED system generating an electrical potential, have limitations in practical applications, e.g. high cost and short durability. Therefore, as the alternative, we developed polyelectrolyte-plugged IEMs supported by anodized aluminum oxide (AAO) arrays. The AAO array consist of well-distributed linear nanochannels but its low surface charge density leads to reduced ion-selectivity by thin electrical double layers (EDLs) formed on the inner wall of nanochannels. When the AAO nanochannels were plugged with ion-selective polyelectrolytes, the polyelectrolytic AAO membrane (PAM) provided excellent ion selectivities and low area resistances. Based on the salinity difference between sea and river water, the electric potential and area resistance of the PAMs were measured. The theoretical power densities calculated from the PAMs were comparable with those of commercially available IEMs. We also investigated the AAO frame influence on the PAM resistance by conducting comparative resistance measurements of a polyelectrolyte-plugged capillary. The results showed that the PAM resistance, for the higher power density, could be decreased by optimizing the AAO frame, e.g. expanding the porosity or reducing the membrane thickness.