Not more than 1 % of Earth’s water is fit to drink. Eliminating salt as well as other minerals from our largest available source of water i.e. seawater might help in satisfying a rising global population thirst. It includes fresh water for farming, transportation, cooling, heating, and industry. However, desalination is an energy demanding method that concerns those who want to develop its application.
Currently, a team of researchers in the Department of Energy’s Oak Ridge National Laboratory had revealed an energy effective technology. For desalination that utilizes a porous membrane made up of strong, slim graphene (carbon honeycomb one atom thick).
“Our work is a proof of principle that demonstrates how you can desalinate saltwater using free-standing, porous graphene,” voiced Shannon Mark Mahurin of ORNL’s Chemical Sciences Division, who co-headed the analysis along with Ivan Vlassiouk in ORNL’s Energy as well as Transportation Science Division.
“It’s a huge advance,” says Vlassiouk, indicating a treasure of water travels over the porous graphene membrane. “The flux through the current graphene membranes was at least an order of magnitude higher than [that through] state-of-the-art reverse osmosis polymeric membranes.”
Prevailing methods for cleansing water comprises distillation as well as contrary osmosis. Distillation, or else heating a mixture in order to extract unstable components that condense, necessitates a substantial amount of energy. Reverse osmosis, a more energy efficient process that nevertheless necessitates a reasonable amount of energy. It is the base for the ORNL technology.
Creating pores in the graphene is vital. Devoid of these holes, water cannot travel from one part of the membrane to other part. The molecules of water are basically too big to fit over graphene’s acceptable mesh. However poke holes in the mesh that are just the right size, and water molecules can penetrate. Salt ions, in contrast, are larger than water molecules and cannot cross the membrane. The porous membrane lets osmosis, or the passage of a liquid through a semipermeable membrane to a solution in which the solvent is even more concentrated.
“If you have saltwater on one side of a porous membrane and freshwater on the other. An osmotic pressure tends to bring the water back to the saltwater side. But if you overcome that, and you reverse that, and you push the water from the saltwater side to the freshwater side — that’s the reverse osmosis process,” Mahurin explicated.