HYDERABAD: Researchers from the Indian Institute of Technology-Hyderabad have developed a way to use fly ash, an environmentally-harmful waste product that is majorly derived from burning coal in thermal power plants, as a material to make water-repellent structures with industrial applications.
In their efforts to mimic the hydrophobic characteristics of lotus leaves and rose petals, the researchers found that when the fly ash is coated with stearic acid, it can be modified into a water-repellent material.
Such materials find usage in manufacturing a wide range of applications like in anti-fouling paints, anti-sticking surfaces for antennae, self-cleaning coatings for automobiles, etc. This water-repellent material can also be used to protect concrete structures from rain and moisture-induced damage.
The research was jointly undertaken by Dr Mudrika Khandelwal and Dr Atul Suresh Deshpande of the Department of Materials Science and Metallurgical Engineering at IIT Hyderabad. Dr Mudrika Khandelwal said: “The water repellence properties of the lotus leaf and rose petal have been a matter of discussion for a long time, and scientists have explored ways in which these structures can be made artificially.” Highlighting the difference in the water repellent nature of lotus leaf and rose petal, she said that while water drops slide off the lotus leaf, they stick to rose petals.
According to Dr Atul Suresh Deshpande, the particle size of fly ash is between 100 nanometres to a few micrometres, a size range that is suitable for generating rough surfaces that are hydrophobic. “However, fly ash itself is not water repellent, and therefore, we coated stearic acid on the particles,” he said. He explained that coating fly ash particles with stearic acid before depositing it on the surface led to the lotus leaf effect, whereas depositing fly ash particles and then coating it with stearic acid resulted in the rose petal effect.