A potential method to efficiently get potable water from seawater
Producing potable water through desalination may become more efficient and less energy-intensive if researchers at the University of Manchester are able to successfully use graphene oxide (GO) membranes to filter common salts in seawater on a commercial scale.
The use of GO as a molecular sieve to filter common salts from seawater while allowing water to pass through it is already known.
Problem with the GO membranes
GO membranes have a tendency to slightly swell when immersed in water and this results in increased spacing between successive sheets (akin to increasing the pore size of a sieve).
The increased spacing allows smaller salts to flow through the membrane along with water without being filtered.
What has happened now?
National Graphene Institute, University of Manchester, has addressed this problem by developing GO membranes that do not swell when immersed in water and are able to sieve common salts.
The water molecules that get strongly bound to common salts increase the diameter of salt ions and are hence unable to pass through the tiny space between the sheets; water molecules with weak hydrogen bonding are easily able to pass through the membrane. The membranes developed by the team can be used for waste water treatment even when no energy is supplied.