Nanoporous graphene as a water desalination membrane
Massachusetts Institute of Technology. Department of Materials Science and Engineering.
Jeffrey C. Grossman.
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Desalination is one of the most promising approaches to supply new fresh water in the face of growing water issues. However, commercial reverse osmosis (RO) techniques still suffer from important drawbacks. In order for desalination to live up to the water challenges of this century, a step-change is needed in RO membrane technology. Thanks to significant advances in the field of computational materials science in the past decade, it is becoming possible to develop a new generation of RO membranes. In this thesis, we explore how computational approaches can be employed to understand, predict and ultimately design a future generation of RO membranes based on graphene. We show that graphene, an atom-thick layer of carbon with exceptional physical and mechanical properties, could allow for water passage while rejecting salt ions if it possessed nanometer-sized pores. Using computer simulations from the atomic scale to the engineering scale, we begin by investigating the relationship between the atomic structure of nanoporous graphene and its membrane properties in RO applications. We then investigate the thermodynamics, chemistry and mechanics of graphene and the water and salt surrounding it. Finally, we establish the system-level implications of graphene's promising membrane properties for desalination plants. Overall, this thesis reveals that graphene can act as an RO membrane with two orders of magnitude higher water permeability than commercial polymer membranes as long as the nanopores have diameters around 0.6nm, that graphene is strong enough to withstand RO pressures as long as it is supported by a substrate material with adequate porosity, and that a nanoporous graphene membrane could ultimately reduce either the energy footprint or the capital requirements of RO desalination. Ultimately, this thesis highlights a path for the development of next-generation membranes for clean water production in the 21st century.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.Cataloged from PDF version of thesis.Includes bibliographical references (pages 147-162).
DepartmentMassachusetts Institute of Technology. Department of Materials Science and Engineering.
Massachusetts Institute of Technology
Materials Science and Engineering.