Bubble-propelled micromotors shown to purify wastewater

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Researchers from the Institute of Chemical Research of Catalonia (ICIQ) have developed micromotors that can move autonomously to purify wastewater.

Micromotors are very small particles (measured in microns) that can move themselves. These micromotors, made of silicon and manganese dioxide, release bubbles that act as a motor to propel them.

Researchers coated the micromotors with a chemical compound called laccase, which accelerates the conversion of urea in polluted water into ammonia.

To optimise the design of the micromotors, the researchers developed a deep-learning based tracking system to precisely measure the speed of the micromotors. The artificial intelligence (AI) technology will help in the development and optimisation of these micromotors for trials in water treatment plants.

“If we cannot monitor the micromotor, we cannot develop it. Our AI works well in a laboratory environment, which is where the development work is currently underway."

Harshith Bachimanchi, University of Gothenburg

Urea is a naturally occurring organic compound and the end product of the metabolic breakdown of proteins in all mammals and some fishes. It occurs not only in urine, but also blood, bile, milk and perspiration.

There are several ways that urea can get into water bodies: it can leach from landfill sites, flow from wastewater treatment facilities and run-off agricultural lands. Urea can have both immediate and long-term effects when it gets into water.

It provides algae with nutrients, causing them to grow quickly - which can lower oxygen levels and jeopardise water ecosystems. Extended exposure to high levels of urea in water upsets the natural equilibrium, causing native species to disappear and invasive species to thrive.

The researchers found that converting urea into ammonia not only helps with water treatment but also provides a source of green energy. While further development and modifications are needed before these micromotors can be implemented in large-scale trials for urban water treatment plants, this research is promising and demonstrates the potential application of bio-catalytic micromotors in environmental remediation and green energy generation.