In the past 30+ years, polymer membranes have emerged as a viable and widely used technology to separate gas mixtures and purify water via desalination and filtration of, for example, wastewater. In desalination, for example, reverse osmosis membranes are the dominant technology for desalinating seawater, displacing thermally driven processes in much of the world. In gas separations, polymer membranes are widely used for air separation and hydrogen purification, and they are increasingly being used for natural gas separation.
In recent times, focus on grand challenges facing mankind, including development of energy-efficient methods to provide clean water in both the developed and developing world and mitigate carbon dioxide levels in the atmosphere, have driven research into new platforms of membranes in our laboratories. Additionally, the strong and often competing connections between water, energy, and food production, coupled with the shale gas and shale oil revolution currently under way in the United States, are providing new opportunities for low-energy separations.
This presentation will focus on two stories, each illustrating pathways beginning from fundamental molecular engineering of polymers to tune their properties for specific separations, followed by scale-up and commercial deployment. In one case, membrane materials were developed with a specific affinity for CO2, resulting in membranes that are currently used for CO2 removal from H2 in H2 production and in large-scale field tests for post-combustion carbon capture. In the second case, beginning from Office of Naval Research sponsored research in the 1990’s, focused on separation of oil/water emulsions in bilgewater about Navy ships, porous membranes used for water filtration were surface modified to improve their lifetime and performance (i.e., resistance to fouling). Systematic tuning of the chemistry and application of these nanometer-thick surface modification coatings led to fouling-resistant, energy-efficient membranes now in commercial production for the oil and gas industry (purification of flowback water from hydraulic fracturing, desalination of water for fracking operations), municipal wastewater purification, and rural desalination. Finally, the presentation will provide a short section on a forward-looking view of the bright future emerging for fundamental science to drive innovation in polymer membranes for both new and existing applications.