Abstract: Understanding and controlling fluid flow in nanostructured materials offers new opportunities in advancing membrane technology for water filtration, desalination, gas separations, and other applications. In this talk, we first present the development of monolayer nanoporous graphene as an ideal ultrathin membrane material that promises high flux, tunable properties, and chemical resistance. We show that a high density of sub-nanometer pores can be created by nucleation and oxidation of defects, and fabricate leakage-tolerant membranes to quantify the effect of porosity on selective mass transport and nanofiltration. Next, we present the concept of using larger nanostructures that trap vapor nanobubbles as a selective medium for water desalination. This approach combines the advantages of thermal desalination and reverse osmosis while providing fundamental insights into the behavior of water at the nanoscale. Finally, we discuss our work on using naturally occurring porous plant xylem – the tissue that conducts sap in plants – as a selective material for low-cost water disinfection. These studies illustrate the interplay between material structure and nanofluidic flows and demonstrate potential for the realization of next-generation membranes for water desalination, filtration, and gas separations.
Bio: Rohit Karnik is Associate Professor of Mechanical Engineering at the Massachusetts Institute of Technology, where he leads the Microfluidics and Nanofluidics Research Group. His research focuses on the physics of micro- and nanofluidic flows and design of micro- and nanofluidic devices for applications in healthcare, energy systems, and bioseparation and analysis. He obtained his B. Tech. degree from the Indian Institute of Technology at Bombay in 2002, and his PhD from the University of California at Berkeley in 2006 under the guidance of Prof. Arun Majumdar. After postdoctoral work with Prof. Robert Langer at MIT, he joined the Department of Mechanical Engineering at MIT in 2007. Among other honors, he is a recipient of the Institute Silver Medal (IIT Bombay, 2002), NSF Career Award (2010), Keenan Award for Innovation in Undergraduate Education (2011), DOE Early Career Award (2012), and IIT Bombay Young Alumni Achiever Award (2014).