Computational Simulation Studies of Membrane Fouling Mechanisms and Designing New Antifouling Membranes

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The shortage of potable water is becoming an increasingly challenging issue in the world. Today, about 1.1 billion people, roughly one sixth of the world's population, live in areas without enough safe drinking water. Water contaminants can be removed using a membrane separation process. Membranes allow purified water to pass while retaining the contaminants. However, the contaminants can build up and foul conventional membrane technologies. Foulants reduce membrane performance, require regular membrane cleaning, and increase energy consumption. The mechanism by which membranes foul, and what chemical attributes contribute to membrane fouling, are not well understood on a fundamental molecular level. This research project will advance computational models for a widely used polymer membrane and develop efficient simulation methods to provide fundamental understanding of fouling mechanisms. The project will use the new computational tool to explore strategies of designing high-performance, antifouling membranes for water purification.This project targets fundamental questions of membrane fouling and proposes new strategies for designing antifouling membranes through surface modification, mainly by grafting different polyzwitterion coatings. Research objectives include: (1) developing computational models for polyamide membranes and foulants, in which the membrane surface model can properly represent the surface chemistry and morphology based on available experimental datasets; (2) developing a combined nonequilibrium molecular dynamics screening and equilibrium umbrella sampling technique to accurately search for the lowest free energy fouling sites and fouling configurations for a membrane-foulant complex system; and (3) using the developed computational models and tools to perform extensive molecular simulations to investigate surface modified polyamide membrane and its antifouling properties, proposing new strategies for the molecular design of antifouling materials. The project provides an important opportunity for students to obtain education and training in simulation-based engineering and science research. One graduate student will be trained in this project. Undergraduate and high school students, including women and minority students, will participate in the program through the support of institution summer undergraduate program for education and research.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.