Researchers from the National Graphene Institute and the University of Manchester have created a new graphene filter that has been shown to be impermeable to solvents except water. The process involves making molecules ultrathin.
Ultra-thin membranes were developed that allow pinholes that are interconnected with nanochannels to allow an atomic-scale sieve to allow large solvents to pass through the membrane.
The breakthrough will allow graphene membranes to be used in a wide array of application from home water filters to sea water desalination and solvent nanofiltration. The process can be used to separate organic compounds from solvents in sea water.
Organic dyes can also be removed using the graphene-oxide membranes that allow for the removal of dyes as small as a nanometer.
The team even filtered whisky through their membrane. The alcohol was allowed to pass through but the amber color of the whisky was removed. The team states that the whisky still smelled the same, but as per the labs rules, the team was not allowed to taste their clear whisky.
“Just for a fun, we even filtered whisky and Cognac through the graphene-oxide membrane. The membrane allowed the alcohol to pass through but removed the larger molecules, which gives the amber colour. The clear whisky smells similar to the original whisky but we are not allowed to drink it in the lab, however it was a funny Friday night experiment,” said lead researcher.
The technology will have a wide range of applications in the pharmaceutical and chemical industries, according to the team. The technology also has the potential to consume half of the industrial energy needed to separate molecules from organic solvents. The team claims that by 2030, the world is projected to consume 60% more energy than today. The separation process is efficient, allowing for low energy usage and lower energy-related costs.
Graphene-oxide membranes have a high potential to help combat water scarcity, allowing researchers to be able to develop new ways to filter salt water.
The ability to filter specific solvents and molecules opens a whole new perspective to the industry. Filtration can now be refined to specific uses, which includes allowing chemical companies to purify their water, or allowing pollutants in water to be removed through the membrane.
Previously, graphene-membranes were highly efficient and effective, yet they only allowed water to pass through the membrane. The application was limited. Now, the membranes can be customized to allow other solvents to properly pass through the membrane.
Dr. Su, the experiment’s leader, states, “The developed membranes are not only useful for filtering alcohol, but the precise sieve size and high flux open new opportunity to separate molecules from different organic solvents for chemical and pharmaceutical industries. This development is particularly important because most of the existing polymer-based membranes are unstable in organic solvents whereas the developed graphene-oxide membrane is highly stable.”
Graphene is a million times thinner than a human hair and flexible, yet the material is also stronger than steel. The versatility of graphene has made it a popular choice in filtration research and development.