Researchers Develop Self-cleaning Coating Material from Rice Husk

Corrosion is a big problem the world over and is said to cost around $2.5 trillion globally, which is equal to 3.4 percent of global GDP.

The organic coating material developed by the team of researchers led by Harpreet Singh Grewal of the Department of Mechanical Engineering at Shiv Nadar University (SNU), addresses a number of problems in just one go.

Smart coating material with self-cleaning properties from rice husk, which when applied on a range of surfaces, can help fight adverse effects of corrosion and dust.

Apart from producing a high-value material with wide-ranging industrial and household applications from agricultural waste, it aids in significantly reducing water used for cleaning. Besides, it has the potential to replace toxic substances-based paints that are normally used.

The journal Progress in Organic Coating featured recently their work.

For making this novel coating material, the researchers first extracted nano-silica particles that are present in rice husk by burning the husk at high temperatures. These nano-silica particles — that are nearly 250 nanometres (one nanometre is one-billionth of a meter) in size — is mixed with a solution of silicone oil and toluene, a commonly used solvent. The solution is now ready to be used for spray painting.

“The coating material can be used on a variety of surfaces including concrete, steel structures, and even wood,” said Grewal, who joined SNU in 2015 after completing his Ph.D. from the Indian Institute of Technology, Ropar and a post-doctoral degree from South Korea.

He said his team that also included a colleague Harpreet Arora and Grewal's masters and doctoral students, was inspired to take up this work as they wanted to find a way to put locally available agricultural waste materials to better use.

“The material has sufficient roughness and water-repelling properties that dust particles cannot remain on the coated surfaces for long. When very little quantity of water is sprayed, water droplets will roll off these surfaces taking dust and other particles along with them, just like what happens when they fall on lotus leaves,” said Grewal.

“Our calculations show that for cleaning one square inch surface, we just need 30 to 40 microlitres (one microlitre is one-millionth of a litre) of water, which is 5 to 10 times lesser quantity of water needed for conventional cleaning,” he said.

Moreover, the coating is non-toxic unlike lead- or chromium-based paints and can be applied on all household appliances, buildings, automobiles, and industrial components. Besides, it’s been found to be very durable,” said Grewal, whose team carried out this research under a project sponsored by the Council of Scientific and Industrial Research.

Even though the scientists did not ascertain the cost of the coating material, it may not be very expensive, according to Grewal. “My hunch is that we may be able to produce 1 liter of material for ₹50 to 100,” he said, adding that 20 to 30 kg of nano-silica can be produced from 100 kg of rice husk.

In the immediate future, the scientists want to see whether similar hard protective coverings found in wheat can help produce nano-silica, apart from finding a replacement solvent for toluene, which is a by-product of fossil fuel.