VATIS UPDATE Article

Scientists from the Indian Institute of Science (IISc), India, have developed a novel ‘reusable’ nano-composite material, with Cerium being the crucial compound in it, which can degrade microbes and chemical dyes that are among common effluents in rivers. The scientists looked at ceria (CeO{-2}) a cheap rare earth oxide with properties that include a strong absorption of ultraviolet light (this property also sees it being widely used for UV-blocking and radiation shielding agent).

It is this notion, that the compound can speed up the degradation of chemical dyes and the bacterium Escherichia coli (which forms a large chunk of organic waste in sewage) led the researchers to develop ceria nanoflakes, which combines ceria with silver salts. In this composite, ceria absorbs light across the spectrum (and not just UV light), while the silver salts (silver phosphate, and silver bromide) form photocatalysis agents, where chemical reactions are accelerated in the presence of light.

The results showed that the composite material ended up generating large amounts of hydrogen peroxide (a strong oxidizing agent) that degrades the dyes and bacteria. Within 60 minutes, nearly all of methylene blue and methyl orange (both common chemical dyes) were degraded by the composite. In comparison, ceria-silver phosphate compound that had been synthesized previously, researchers managed to degrade the chemical dyes by 80 per cent in this time frame.