Engineering the Next-Generation of Membrane Materials Needed to Achieve Global Water Sustainability Goals

Dr. Eric Hoek will begin this talk with a brief overview of past and ongoing food-energy-water nexus research in the UCLA Nanomaterials, Membrane & Electrochemical Technologies Research (NanoMETeR) Lab, including a few attempts to translate basic research discoveries into commercial innovations. Then, I will present new results––both experimental and theoretical––on a new class of fully thermoset reverse osmosis (RO) membrane materials designed to operate at extreme temperatures and pressures. Conventional RO membranes comprise an ultra-thin, microporous cross-linked (thermoset) polyamide (PA) film formed over a mesoporous polysulfone (PSU) (thermoplastic) support membrane, which is cast over a macroporous nonwoven polyester fabric. The thermoplastic PSU supports experience permanent deformation and damage via plastic creep when exposed to high applied pressure (>50 bar) and/or feed solution temperature (>30 ºC), while the thermoset PA layer physically compacts under pressure, but recovers its original free volume upon pressure relief. We have employed advanced modeling methods such as density functional theory, molecular dynamic simulations and a novel “material point method” along with traditional wet-testing experiments and ex situ light and electron microscopy plus novel X-ray computed tomography (CT) and focused ion beam-electron microscopy CT to elucidate the fundamental mechanical properties and resulting performance characteristics of conventional and fully thermoset RO membranes. These new high-pressure/-temperature tolerant RO membranes can serve applications that have long been exclusively in the domain of thermal technologies. If scalable, RO membrane-based solutions could be half the capital cost and half the energy demand of traditional thermal-based separation processes.