Potential Desal Competitor Uses Graphene Oxide

Existing desalination systems may have a new competitor: the graphene-based sieve.

A University of Manchester research team created a new way to remove salt from water, publishing their findings in the journal Nature Nanotechnology this month. They used permeation experiments and simulations to “show that physically confined graphene oxide allows water molecules to pass through while hindering hydrated ions,” the study said.

Engadget summarized the advantages of the technology: “It's highly efficient in filtering the salt out of saltwater and could lead to a less energy-intensive desalination process. The team's sieve is made of graphene oxide, an oxidized form of the material that could be easier and cheaper to produce in large quantities than the typical graphene.”

Graphene oxide had already been used to filter out larger substances, but this is the first time it was used to filter something as tiny as common salts, according to BBC News.

“Previous work had shown that graphene oxide membranes became slightly swollen when immersed in water, allowing smaller salts to flow through the pores along with water molecules. Now, [the researchers] demonstrated that placing walls made of epoxy resin (a substance used in coatings and glues) on either side of the graphene oxide membrane was sufficient to stop the expansion,” the news report said.

Graphene can be generated through oxidation processes in a research lab, the report said.

Study author Rahul Nair explained to BBC News: "As an ink or solution, we can compose it on a substrate or porous material. Then we can use it as a membrane. In terms of scalability and the cost of the material, graphene oxide has a potential advantage over [other methods]."

The system will now be tested against commercialized desalination techniques.

"This is our first demonstration that we can control the spacing [of pores in the membrane] and that we can do desalination, which was not possible before. The next step is to compare this with the state-of-the-art material available on the market," Nair said, per the BBC News report.

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