Modern production technologies from brewing waste

MONTREAL — The leftovers from brewing can be turned into infinitely small crystals that are used in the production of advanced technologies, researchers from the National Institute for Scientific Research (INRS) and the Graduate School of Technology have found.

Called “quantum dots,” these crystals are actually “nanocrystals,” each measuring only a few billionths of a meter (one nanometer equals one billionth of a meter).

Usually made from heavy metals and pollutants like cadmium and lead, these quantum dots could instead be made from grain, leftover cereals from breweries that have been reused in animal feed in recent years.

Quantum dots are used, among other things, to emit and absorb light, for example as sensors in biomedicine or as LEDs in next-generation displays. In particular, the South Korean giant Samsung is devoting huge resources to the synthesis of quantum dots for use in its phones.

“It can also be used for applications that are a little less mature from a technological and commercial point of view, such as solar technology, that is, the absorption of light to convert it into another form of energy,” explained Professor Federico Rosei from INRS.

“It could be electricity that can be used to break down water molecules and separate hydrogen from oxygen. And then hydrogen can be used as a clean fuel.”

Professor Rosei and his colleagues demonstrated this spring in the pages of the magazine RSK Advances Royal Society of Chemistry that using improvised means it is possible to produce carbon quantum dots.

They used a home microwave to char the pellet, creating a black powder that was then mixed with distilled water and returned to the microwave. Passage through a centrifuge and advanced filtration steps yielded quantum dots.

The finished product is capable of detecting and quantifying heavy metals as well as other contaminants affecting water quality, the environment and health.

“We can modulate the properties of quantum dots by changing their size, morphology and composition,” said Prof. Rosei.

Quantum dots, which show the best performance, he continues, unfortunately contain heavy metals, the use of which is far from desirable from an environmental point of view. Therefore, we sought to replace them with non-toxic and, ideally, very common elements.

The raw material contains elements such as carbon, nitrogen and phosphorus, which will contribute to the efficiency of the resulting quantum dots. Previous work has shown that carbon-derived quantum dots are interesting in that they capture sunlight and convert it into another form of energy.

This project was completed thanks to a collaboration with the microbrewery Brasseur de Montréal, who provided their leftover grains. Now the researchers do not rule out contact with a larger brewery that may be interested in this technological breakthrough.

“The basic principle is to try to recover the waste,” said Prof Rosei.

But good. From here to the conclusion that the more beer you drink, the more you will help our hospitals equip themselves with the advanced equipment they need, there is certainly a step we must be careful not to cross.