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IIT-H Researchers develops water repellent structures using industrial waste product ‘ fly ash’

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Researchers from Indian Institute of Technology Hyderabad (IIT-H) have
developed water repellent structures by using an industrial waste product ‘ fly ash.’
Such ‘super hydrophobic’ (super water repellent) structures has significant industrial applications such as anti-fouling paints, anti-sticking surfaces for antennae, self-cleaning coatings for automobiles, stain-resistant textiles, anti-soiling architectural coatings and among others, the Institute said in a release in Hyderabad on Thursday.

The water repellent product is not only much cheaper than other super hydrophobic coatings developed so far but also serves towards up-cycling an industrial waste material – fly ash – into an industrially useful product, which serves the double purpose of side-revenue and waste management, the release said.

The Research was jointly undertaken by Dr. Mudrika Khandelwal and Dr. Atul Suresh Deshpande, Department of Materials Science and Metallurgical Engineering, IIT Hyderabad while their research paper, co-authored with  Urbashi Mahanta, was recently published in the reputed peer-reviewed journal Chemistry Select.

Speaking about their research, Dr.Khandelwal said, “The water repellence properties of the lotus leaf and rose petal have been known for a long time, and scientists have explored ways in which these structures can be made artificially for various applications.

Mimicking natural structures for engineering applications was not easy and in order to artificially replicate a natural phenomenon, scientists must understand the relationship between the natural structure and the purpose it serves, Dr.Khandelwal added.

Highlighting the economic aspect of their research, Dr. Deshpande said, “We have used an inexpensive material, fly ash, a waste product from the coal industry, to obtain hydrophobic surfaces with tailorable water adhesion behaviour. 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 (researchers) coated stearic acid on the fly ash particles.”

“Using these surface modified fly ash particles, the researchers were able to obtain surfaces with different adhesion properties. Whether the water drops rolled off (‘lotus leaf effect’) surfaces coated with the fly ash or stuck to the surface (‘petal effect’) depended upon when the stearic acid was coated on the fly ash particles.

“Coating the fly ash particles with stearic acid before depositing the fly ash on the surface lead to the lotus leaf effect, whereas depositing fly ash particles and then coating them with stearic acid resulted in the rose petal effect”, Dr Deshpande explained.
Dr. Khandelwal said, “Our method for producing water repellent surfaces is quick and highly scalable as it does not require any sophisticated instrument.”
The synthesis process is so simple that even an untrained individual can apply it to obtain superhydrophobic surfaces at a low cost.

Dr. Deshpande also said that the superhydrophobic (super-water-repellent) coatings produced using fly ash can be used to protect concrete structures from rain and moisture induced damage. In addition, these materials can be used for water harvesting applications, he added. (UNI)