Researchers from the Indian Institute of Technology Guwahati have developed a graphene-based superhydrophobic material that can separate oil and water.

The team has developed hierarchically-structured graphene oxide nanosheets that can selectively separate oily or aqueous contaminates from both oil-in-water and water-in-oil emulsions.

The research paper was recently published in the Royal Society’s journal, Chemical Science, and has been authored by Uttam Manna, associate professor, department of chemistry, IIT Guwahati, along with his research scholars Avijit Das, Kousik Maji and Sarajit Naska, an IIT statement said on Wednesday.

Asked whether the research was still in the trial stage or had been approved and when would it be commercially produced, Manna said, “This development is very fresh and remains under laboratory scale. We are looking for industrial partnership.”

Oil-water separation techniques have a number of industrial and environmental applications. Various porous and bulk substrates such as sponge that are made superhydrophobic have been used to absorb oil from oil-water emulsions.

For example, oil refineries have a lot of wastewater, which has oil contaminants which affect the waterbodies where it is discharged. Again, when crude oil is transferred, oil spillage can take place, a famous example of this being the Mexican oil spillage accident. It led to a lot of changes in the aqua ecosystem. Oil accidents have short and long-term severe impact on the aqua ecosystem, Manna said.

Superhydrophobic materials, which have extreme water repellence, are considered best for removing oil from water. They are being studied for applications such as water purification and self-cleaning surfaces. But they are generally not scalable, use environmentally toxic products such as fluorinated polymers and have poor mechanical and chemical stability.

The researchers have manipulated graphene, a form of carbon, to have superhydrophobic properties suitable for separation of oil from water in emulsions, Manna said. The IIT Guwahati team has developed a facile method to produce graphene oxide-polymer composite with hierarchical topography and low surface energy chemistry in the confined space. Such graphene oxide showed “confine-super-water-repellence”.

The researchers further deposited iron oxide nanoparticles on the two dimensional nanosheets, which made the material magnetically active.

“Our graphene oxide composites were able to separate oil from water in emulsions with high efficiency,” Manna said. The uniqueness is that the separation can be brought about even under extremes of pH, salinity, surfactant contaminations as is seen in real life scenarios.

“This chemically/magnetically active 2D-nano-interface could help in the development of functional interfaces for various applications related to energy, catalysis and healthcare,” Manna said.


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