Indian Institute of Technology Guwahati researchers have developed a novel highly porous and water repellent superhydrophobic cotton composite material containing Metal-Organic Framework (MOF), which can absorb oil selectively from an oil-water mixture. 

The MOF composite has great capability for selective separation of the oils from oil/water mixtures, and the separation efficiency lies between 95 per cent and 98 per cent, irrespective of the chemical composition and density of the oils. 

Besides, the MOF composite is also able to absorb large volumes of oils and can be reused a minimum of 10 times so that the sorbents can provide more recovery of the spilt oil. 

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The practical applications of this Research include

• Cleaning the spilt oil from environmental water (river, sea or ocean water) during oil transportation with high efficiency and large absorption capacity, thus reducing environmental water pollution
• Both heavy and light oils can be effectively absorbed by the material
• The material is easy to prepare, cost-effective and recyclable

The research team was led by Shyam P. Biswas, Associate Professor, Department of Chemistry. IIT Guwahati. The results of this pathbreaking work have recently been published in the reputed peer-reviewed journal ACS Applied Materials and Interfaces belonging to the American Chemical Society.

In the petroleum industry, oil leakage and oil spill accidents happen frequently during offshore oil exploitation and oil transportation. This severe water contamination threatens the health of human beings including other living species. Therefore, the treatment of industrial oily wastewater and the separation of oil spills from water has become a worldwide challenging task. 

To overcome this problem, the IIT Guwahati researchers have synthesized a superhydrophobic MOF composite with cotton to absorb oil selectively from water. 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. 

The team led by Biswas initially developed a superhydrophobic MOF which can repel the water and float on the water surface. Then, they grew the same MOF on the surface of medical cotton. It was observed that the medial cotton changes from hydrophilic to superhydrophobic material and can float on the water surface. The MOF-coated cotton fibre composite showed water repellence with a water contact angle (WCA) of 163°. 

The flexible superhydrophobic MOF composite showed an oil absorption capacity of 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 a collection of underwater oil against gravity. 

The growing environmental pollution is a serious threat to our society for sustainable development. Among the various environmental problems, water pollution is one of the serious issues in India. Until now, petroleum hydrocarbon products are the main energy sources in the world.