Abstract
The salinity gradient between brine and fresh water is an abundantsource of power which can be harvested by two major membrane methods:pressure-retarded osmosis and reversed electrodialysis. Nowadays, the lattertechnology is close to real application, but it still suffers from low power yield. Lowmembrane selectivity and complex membrane fabrication are the main limitingfactors. To improve that, we design a couple of ion-selective membranes based onthe track-etched polymer nanopore functionalized by highly charged hydrogels.Two nanopore geometries are compared (cylindrical and conical shape) togenerate osmotic energy with gel functions and more importantly can be scaledup. Experiments from the single nanopore and multipore membrane to stackedmembranes show complete characterization from ionic transportation to energygeneration and a clear relationship from the single pore to stacked membranes. Inthe actual experiment conditions, a power density of 0.37 W m−2 at pH 7 wasachieved. By improving ionic tracks and reducing intermembrane distances, it canbe a good candidate for industrial applications.