Nano-silica from farm waste? Cusat researchers show how it is done
KOCHI: What’s an alternative to inorganic acids such as nitric acid, sulphuric acid and hydrochloric acid? What can replace sand to produce high-quality silica needed in the tyre-manufacturing industry?
The answers to these questions have been provided by researchers at Cochin University of Science and Technology (Cusat). Their efforts have yielded a cost-effective method to produce silica from rice husk, with the help of oxalic acid extracted from the bilimbi fruit.
Speaking about their research, C D Midhun Domenic said, “A major problem today is the improper management of biomass after cultivation and harvesting. Among the cereal crops, the milling of paddy produces large amounts of waste, which is the husk.”
“Usually this waste is dumped in landfills or burned in the open. But these traditional methods can cause severe environmental issues,” he said. Since silica is abundant in rice husk, considering it for silica extraction could be a strong tool for the disposal of this solid waste, said Midhun. The use of rice husk for a valuable outcome can also be a significant move for the circular economy, he added.
According to Dr P M Sabura Beegam, head of the Department of Applied Chemistry, the study is unique in another way. “It is the replacement of conventional acids with green acids, such as Averrhoa bilimbi juice, that are rich in oxalic acid. We found that the metallic impurities from the rice husk can be removed using bilimbi fruit juice for the preparation of nano-silica with excellent purity and high surface area,” she said.
We found an affordable and innovative way to extract nano-silica from rice husks using the bilimbi fruit. “The fact that there hasn’t been any research on the extraction of nano-silica by calcinating bilimbi pre-treated rice husk makes our research very innovative,” she added. The silica thus extracted can be used as a filler in the manufacture of tyres.
It has been found that the use of nano-silica with higher surface area has worked towards reducing the rolling resistance of tyres. “This can be achieved by replacing most of the carbon black filler with nano-silica,” said the researchers.
According to them, the economy of Kerala, with its extensive paddy cultivation and small-scale irrigation systems, can be strengthened sustainably by processing and developing products out of agricultural waste.