By: Dr. Franyi Sarmiento, Ph.D., Inspenet, April 13, 2022
A group of scientists from the University of Hiroshima created the first LED emitter based on rice hulls, realizing the possibility of transforming agricultural waste into low-cost light emitters.
That’s a breakthrough, as grinding rice to separate the grain from the hulls produces around 100 million tons of waste worldwide each year.
The researchers base their research on the luminescent properties of porous silicon, which is an abundant material in nature. Rice husks are a source of high purity silica and after processing them, crystalline particles are obtained capable of offering a luminescence efficiency of more than 20%.
“Since typical quantum dots often involve toxic material such as cadmium, lead, or other heavy metals, environmental concerns have been frequently raised when nanomaterials are used. Our proposed process and manufacturing method for quantum dots minimizes these concerns,” said Ken-ichi Saitow, lead author of the study and a professor of chemistry at Hiroshima University.
The team used a combination of grinding, heat treatments, and chemical etching to process the rice hull silica. They started by grinding rice husks and extracted silica powders by burning organic compounds from ground rice hulls.
Second, they heated the resulting silica powder in an electric furnace to obtain silicon powders through a reduction reaction. Third, a purified silicon powder was obtained.
Finally, its surface was chemically treated for high chemical stability and high solvent dispersion with three-nanometer crystalline particles to produce the silicon quantum dots that illuminate in the orange-red range with high luminescence efficiency of more than 20%. .
“The current method becomes a noble method to develop environmentally friendly quantum dot LEDs from natural products,” Saitow remarked.
This breakthrough is just the beginning of a long road in the sustainable energy revolution. Scientists say that the same procedure can be done from bamboo, sugar cane, wheat or barley.
Source Sputnik Mundo : https://mundo.sputniknews.com/20220413/it-is-not-only-the-base-of-your-alimentacion-japoneses-convierten-carcaras-de-arroz-en-luces-led-1124361407. html
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