Abstract

Ion separations in membranes are at heart of several most successful membrane-based technologies, such as desalination and water purification using reverse osmosis (RO) and nanofiltration (NF) and electro-membrane processes such as fuel cells (FC) and electrolysis. These processes are also used to reject or block neutral molecules, e.g., contaminants in NF and fuel in FCs. Yet, despite commercial success and vast empirical knowledge, uptake and transport of ions and molecules in these, mostly polymeric membranes still puzzle membrane scientists as widely adopted classical models often fail to match experimental data. In this talk, we outline a unifying view on selectivity of polymeric membranes as well as nanochannels towards ions and non-electrolytes, which centers on membrane dielectric properties as key physical characteristics that helps maximize selectivity, yet also complicates the physical picture. Subject to time constraints, I will also present a few examples where fundamental understanding helps and guides development of new membrane materials for NF and FC.