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Researchers at the Indian Institute of Technology (IIT) Guwahati have developed a novel, highly porous and water repellent superhydrophobic cotton composite material containing Metal-Organic Framework (MOF), which can absorb oil selectively from oil-water mixture. The material has a separation efficiency of 95 to 98 per cent, irrespective of the chemical composition and density of the oil.
The research was aimed at solving the problem of water pollution.
The practical applications of the research include cleaning spilled oil from river, sea or ocean water. Both heavy and light oils can be effectively absorbed by the material. The material is easy to prepare, cost-effective and recyclable, the institute said.
The research team was led by Dr Shyam P Biswas, Associate Professor, Department of Chemistry. They have published the results in the journal ACS Applied Materials and Interfaces of the American Chemical Society.
Explaining the motive of the research, Dr Biswas said “In our work, we focused on a real problem in environmental water pollution in current time. Our goal was to develop a new material which could be synthesized easily and should be cost effective. We have grown our new MOF material on the surface of medical cotton, which is environment friendly and cost effective. Such low-cost material will reduce the production cost of the material for large scale industrial synthesis for real applications, compared to currently available materials in the market”.
“In a vast country like India where petroleum hydrocarbons are the major sources of fuel, accidental oil spills occur frequently here during transportation and storage of oils. The material developed in our laboratory will certainly be beneficial to reduce the environmental water pollution by efficiently absorbing the spilled oil from environmental water,” Prof Biswas added.
MOFs are a class of compounds containing metal ions coordinated to organic ligands to form 3D structures, with the special feature that they are often highly porous materials that act like a sponge, IIT Guwahati said.
The team initially developed a superhydrophobic MOF which can repel water and float on the water surface. Then, they grew the same MOF on the surface of medical cotton.
They observed that the medial cotton changes from hydrophilic to superhydrophobic material and can float on the water surface. The MOF-coated cotton fiber composite showed water repellence with a water contact angle (WCA) of 163°.
“The flexible superhydrophobic MOF composite showed an oil absorption capacity more than 2500 wt%. Motor oil, kerosene and gasoline were used by the team in this study to investigate the real-life potential of the material for oil-spill clean-up. The research team has also demonstrated the separation of oil from oil/water mixture by simple gravity-directed filtration and also collection of underwater oil against gravity,” IIT Guwahati said.