CAREER: SusChem: Multiscale Modeling for Fluid Separation Across Two-Dimensional Molecular Sieves and Student-Centered Course Reform

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

Joel Eaves of the University of Colorado at Boulder is funded by the Chemical Theory, Models and Computational Methods program in the Chemistry Division to develop fundamental principles, methods, and models for next-generation water purification strategies. Water security is an emerging problem that necessitates the development of new technologies for obtaining potable water. Novel, atomically thin two-dimensional crystals show great promise in water desalination applications, and computer simulations might be effective tools for computational discovery in this endeavor. But with current gaps in both knowledge and methodology, simulations are fundamentally limited in their applicability and scope, and are unable to reliably describe how microscopic motions and interactions connect to figures of merit for reverse osmosis. Eaves and his research group address these gaps by developing concepts, theories, and computational tools that significantly extend computational predictability and utility in modeling and understanding fluid separation across porous two-dimensional crystals. In addition, as part of this CAREER award, Eaves is developing student-centered problem-based learning (PBL) pedagogies at the graduate and undergraduate levels, respectively. PBL is a pedagogy that facilitates active learning by engaging students with real world problems. Eaves plans to develop several PBL modules using some of the computational tools proposed as a virtual laboratory to encourage the kind of student-directed questioning and curiosity that characterizes scientific research. Both the PBL modules and evaluative tools developed will be disseminated over the web. Porous two-dimensional crystals are the ultimate limit in thin semipermeable membranes, but the same length scale disparity that makes them attractive for reverse osmosis applications also makes them challenging to describe using theory and simulation. Using a series of test systems and models, the Eaves and coworkers study fluid separation and passage through atomically thin two-dimensional crystals in regimes of low flow, where near-equilibrium theories apply, and in regimes of high flow, where the system is intrinsically out of equilibrium and current simulation methods are limited. They are testing the hypothesis that the hydrophobicity of the membrane, which can be altered in graphene by electrical, doping, has a measurable and controllable effect on water throughput. In the near equilibrium case, the focus is on a stochastic theory to relate water throughput and ion rejection to spontaneous fluctuations at equilibrium and investigate the reaction coordinates and transition states for water passage and ion rejection. Away from equilibrium, Eaves is developing novel mesoscopic simulation methods that bridge the gap between atomistic simulations and larger scale hydrodynamic and collective variables. In addition, he plans to investigate two-dimensional crystals for water desalination applications other than functionalized, porous graphene.