Surfactant-Assisted on-Acid Interfacial Polymerization of Porous Polymer Membranes for Organic Solvent Nanofiltration

Texas A&M University, College Station TX

Investigators

Abstract

The industrial processes used to manufacture fuels and chemicals often include many energy-intensive separation steps to recover valuable products from the output streams. Current estimates of the energy required to perform these industrial separations range from 10 to 15% of total domestic energy consumption. Replacing conventional separation technologies like distillation with membrane-based filtration processes will reduce industrial energy demand and improve the sustainability of fuel and chemical purification processes. However, relatively few membranes can withstand exposure to harsh organic solutions and high operating temperatures. Existing methods for fabricating polymeric membrane materials have limited ability to produce the types of chemical structures and materials properties needed for organic solvent nanofiltration (OSN) applications. This project will explore a novel strategy to fabricate robust polymer membranes that can be used to reduce the carbon footprint of some of today’s most important and challenging industrial processes, including separating mixtures of benzene, toluene, ethylbenzene, and xylenes (BTEX) and hydrocarbon fractionations. The project will provide opportunities to share the scientific concepts of membrane filtration with members of the College Station, TX, community through the university’s “Chemistry Open House” event. The investigator will also organize a four-day summer camp for regional high school students, where they will learn about the fundamental chemistry and physics of membrane materials. The central project goal is to develop a new strategy to fabricate crosslinked polymer membranes on nonaqueous acid interfaces. This goal will be achieved by elucidating the fundamental mechanism of the surfactant-assisted on-acid interfacial polymerization (SAAIP) reaction, and by addressing the technical challenges associated with fabricating high-quality membranes on nonaqueous acid interfaces. The research plan is motivated by the hypothesis that self-assembled surfactants on an acid interface can promote interfacial polymerization by enhancing local monomer concentration near the interface via electrostatic interactions. This hypothesis will be tested over three research objectives: (1) elucidating the electrostatic interaction-centered mechanism of SAAIP by varying key factors such as acidity, surface tension, self-assembly, and electrostatic interaction; (2) tailoring the kinetics and autonomously optimizing the reaction conditions for SAAIP to access defect-free, ultrathin membranes possessing the desired properties for nanofiltration applications; and (3) demonstrating the SAAIP-enabled unconventional nanofiltration performance for BTEX separation and petroleum fractionation. Successfully developing this on-acid interfacial polymerization strategy will expand the available chemical space for interfacial membrane synthesis beyond the current state-of-the-art aqueous interfacial reactions. As a result, membrane materials with new functionalities, enhanced stability, and the precise molecular selectivity required for OSN will be made possible. This project is supported by the Division of Chemical, Bioengineering, Environmental, and Transport Systems’s Interfacial Engineering program and the Division of Materials Research’s Polymers program. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.