GUWAHATI, May 23 - A team of researchers at the Indian Institute of Technology Guwahati (IIT-G) has successfully developed a graphene-based super-hydrophobic material which can separate oil and water.
Hydrophobic materials are known as non-polar materials with a low affinity to water. This characteristic makes such materials water repelling.
Dr Uttam Manna, Associate Professor in the Department of Chemistry, IIT Guwahati and his team have developed the material and it can separate oil and water from both oil-in-water and water-in-oil emulsions.
“The hydrophobicity of materials is largely governed by the physical architecture and the chemical composition. Therefore, such materials can be rationally created by combining low-surface-energy materials with hierarchical roughness. This is exactly what our group has done,” said Dr Manna.
The research group manipulated graphene, which is a form of carbon, to have super-hydrophobic properties suitable for separation of oil from water in emulsions.
The team developed a simplistic method to produce graphene oxide-polymer composites with hierarchical topography and low surface energy chemistry in the confined space.
“Such graphene oxide species showed confined super water repellence. We deposited iron oxide nanoparticles on the two dimensional nanosheets, which made the entire material magnetically active. Our graphene oxide composites were able to separate oil from water in emulsions with high efficiency. What was unique was that the separation could be brought about even under extremes of potential of hydrogen (pH), salinity and surface active agent or surfactant contaminations as is seen in real life scenarios. Our graphene oxide species was capable of selectively soaking up tiny crude-oil droplets in oil-to-water emulsions with high absorption capacity as well as coalescing larger oil droplets of emulsions from water-in-oil emulsions,” said Dr Manna.
The team’s work recently got published in Chemical Science, the journal of the Royal Society. The research paper was authored by Dr Uttam Manna, along with his research scholars Avijit Das, Sarajit Naska and Kousik Maji.
There are many industrial and environmental applications for oil-water separation techniques.
Dr Manna said that further functionalisation of the chemically and magnetically active two dimensional nano-interface could help in the development of interfaces with new features and capabilities for different applications related to energy and healthcare, among other things.
He added that materials with extreme water repellence capacity are considered best for removing oil from water, and they are being extensively studied for applications such as water purification and self-cleaning surfaces.
“However, the problem with super-hydrophobic materials is that they are generally not scalable or have poor mechanical and chemical stability. In addition, the conventional spongy super-hydrophobic materials are less appropriate for separating oil-in-water emulsions due to poor accessibility of the dispersed oil droplets to the oil absorbing super-hydrophobic interface,” said the research team leader.