To rid water of salt, MIT group
taps thin carbon and computing
Posted October 30, 2012
Water desalination through nanoporous graphene. Click image to enlarge and for more information.
Guided by advanced molecular modeling on supercomputers, Massachusetts Institute of Technology scientists are investigating ways to turn atom-thick carbon layers into membranes for a new and improved desalination method in places with inadequate fresh water.
“Without any actual experimental demonstration, what our calculations tell us is that the performance of the graphene membrane for water desalination would be very high,” says Jeffrey Grossman, a materials scientist who is MIT’s Carl Richard Soderberg associate professor of power engineering and leader of the investigation.
Graphene, first described in 1962 and the focus of the 2010 Nobel Prize in physics, is a chicken-wire mesh of carbon atoms that provides the underpinnings for graphite, charcoal, carbon nanotubes and buckyballs. What has sparked the Grossman group’s interest is graphene’s phenomenal structural strength and chemical attributes that might make it ideal for filtering salt from seawater.
The goal is to drill just-the-right-width, billionth-of-a-meter nanopores into graphene’s normally impenetrable surface so pressurized water alone could get through without damaging the ultrathin structure. That might make it more efficient than the reverse osmosis (RO) process Grossman says now offers the best performance of all seawater desalination options.
The problem is RO has comparatively high costs and energy use. Those faults mean that although seawater is widely available, “dramatically new technologies” are needed to make desalination a sustainable water supply option, Grossman and graduate student David Cohen-Tanugi reported earlier this year in the journal Nano Letters.
