Future of Emerging Carbon-Based Nanomaterials for Seawater Desalination
In the framework of the activities of the new Clean Water Center (CWC) of Politecnico di Torino, seminar with Rahul Prasanna Misra and Daniel Blankschtein (Department of Chemical Engineering, Massachusetts Institute of Technology,
Water scarcity is a major problem facing humanity, with one in ten individuals worldwide currently lacking access to clean drinking water. Seawater, which is too salty for human consumption, can be converted into potable water through seawater desalination. Several previous studies have predicted extraordinarily high water flow rates through carbon nanotubes (CNTs) resulting from an almost frictionless surface at the carbon nanotube wall. Similar to CNTs, 2-dimensional nanomaterials like graphene, which consist of only a single layer of carbon atoms, also possess extraordinarily high water permeability owing to their atomic thickness. The observed high water permeabilities through CNTs and graphene have, in turn, generated tremendous hope for use of these nanomaterials as potential membranes for seawater desalination.
In this talk, I will discuss the advantages of using carbon-based nanomaterials like CNTs and graphene over conventional thin-film composite membranes for seawater desalination. My talk will also include a discussion on developing better modeling approaches to obtain a deeper understanding of the graphene-water interface. In a recent study, by carrying out molecular dynamics (MD) simulations, we have quantified for the first time the important role of the dielectric polarization of graphene on the contact angle of water on graphitic surfaces. Most recently, we have also developed new atomistic polarizable force fields for MD simulations, based on ab-initio calculations, which can accurately model the interactions of water molecules and salt ions with graphene.
Polarizable force fields which can effectively model many-body interactions are expected to unravel new mechanistic insights on the transport of water molecules and salt ions through nanopores in CNTs and graphene, which are beyond the capabilities of existing nonpolarizable force fields used in the literature. Finally, my talk will conclude with a broad discussion on the complementary theoretical and experimental advances required to successfully commercialize carbon-based nanomaterials as ultra-permeable membranes for seawater desalination.