NSF-BSF: Impact of Electric- and Flow-Fields on Surfactant-Stabilized Emulsion Properties During Oil/Water Separation

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The separation of emulsified oil from waste water streams remains a significant industrial challenge. Membrane filtration is one of the few methods that can remove emulsified oil drops. However, the filtration of these drops is complicated by severe membrane fouling, where fluid passage through the membrane is slowed by particles or solutions at the surface. Developing an energy-efficient separation process for removing emulsified oil from water with minimal membrane fouling would benefit many industrial users, including oil and gas producers, food processors, and the shipping industry. The investigators will develop such a process using electrically-conducting ultrafiltration membranes that deliver an electric charge directly to the membrane/water interface. The application of this charge, combined with an appropriately placed counter-electrode, generates electric fields that impact the shape, behavior, and interfacial properties of emulsified oil drops. The affected oil drops no longer contribute to membrane fouling, allowing water to pass through. The first goal of this project is to understand how emulsified oil behavior during membrane filtration with applied electric- and flow-fields influences separation performance and fouling. The second goal focuses on dramatically increasing the conductivity of the ultrafiltration membranes, which will lower the energy requirements of applying an electric field. Completion of the project will develop the fundamental knowledge necessary to design and implement a pressure-driven, membrane-based, oil/water separation process that mitigates membrane fouling by electrically modifying both the membrane surface and emulsified oil drops. The research team will also provide an important STEM pipeline for disabled military veterans through their Research Experience for Veterans Program. They will partner with the University of California, Los Angeles's Center for Accessible Education to identify and recruit disabled veterans seeking a summer research internship. These veteran students will participate in a 12-week summer program that will integrate them into the investigators' laboratories and provide them an opportunity to do graduate-level research in hopes of encouraging them to pursue an advanced degree in a STEM field. This project will explore the combination of electrofiltration and emulsified oil dynamics, with the goal of developing a fouling-resistant oil/water separation process. Since many emulsifying agents carry an electrical charge, it is expected that they will respond to an external electrical field, which will impact the interfacial properties of the emulsified oil drops themselves. Understanding how these complex systems respond to external fields (both electrical and flow) will help elucidate fundamental emulsion properties, with the potential of improving multiple processes where emulsified oils are used. The project will also explore how increasing the conductivity of a percolating network of carbon nanotubes (using conducting polymers, metal ion intercalation, or metal deposition) impacts the overall surface and transport properties of carbon nanotube/polymer electrically-conducting membranes. Maximizing conductivity and transport through the membrane will enable efficient and uniform charge distribution along the membrane surface, which will enable fouling-free operation while decreasing process energy consumption. Developing fundamental knowledge of the impact of electrical fields on the interfacial properties of oil drops accumulated along the membrane surface coupled with highly-conducting porous polymeric materials has the potential of transforming membrane-based oil/water separation processes. The project involves two teams from the U.S. and Israel. Profs. David Jassby and Eric Hoek, from the University of California, Los Angeles, are supported by the Molecular Separations and Particulate and Multiphase Processes programs in the Division of Chemical, Bioengineering, Environmental, and Transport Systems. Prof. Guy Ramon, from Technion-Israel Institute of Technology, is supported by the U.S.-Israel Binational Science Foundation.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.