This blog has recently featured articles on the growing worldwide water crisis and on the potential of a new material called graphene which has exhibited amazing characteristics (strength, chemical resistance, flexibility) that could lead to breakthroughs in a number of areas. It is therefore big news that researchers at the Department of Energy’s Oak Ridge National Laboratory have found that this material, when acting as a membrane in reverse osmosis desalination, can substantially reduce the energy required to make fresh water out of salt water. This is because a thinner and more porous membrane greatly reduces the pressure required to push the (fresh)water through. If the use of graphene in this application can be commercially proved out, desalination would become a much more attractive technology for providing fresh water to regions that desperately need it, not least California.
Getting a little technical, the one atom thick membrane was constructed by flowing methane through a tube furnace at 1000 degrees C over a copper foil that catalyzed its decomposition into carbon and hydrogen. The chemical vapor deposited carbon atoms that self-assembled into adjoining hexagons to form a sheet with a thickness of one atom(!). This sheet was supported on a silicon nitride chip. Oxygen plasma was used to knock carbon atoms out of the nanoscale chicken wire lattice to create pores.
The membrane allowed rapid transport of water and rejected nearly 100 percent of the salt ions. The Center for Nanophase Material Sciences, another DOE unit, assisted with this research. It was published in the March 23 online issue issue of Nature Nanotechnology. (People who know me would attest that I am probably not an avid reader of this journal).
Commercial application must prove out structural stability and resistance to biofouling. which may prove to be a high bar.