Originally published in The Nano Newswire
Researchers at the University of Buffalo have found that cadmium selenide quantum dots degrade in soil, releasing toxic cadmium and selenium ions into the environment. Although not yet commonly used, scientists are seeking to apply these semiconductor nanocrystals to a range of uses, including solar panels and biomedical imaging. Although the researchers hope that chemical modifications will eventually prevent such biodegradation in soil, the study found that a protective, zinc-sulfide shell was ineffective in preventing degradation and the resultant release of toxins into the environment. In fact, the biodegradation occurred in as little as 15 days after entering the soil. The study also examined the distance and rate of speed at which the released material moves through soil. In laboratory tests, it was found that the majority of the material remains within a couple inches of the soil surface under normal weather conditions, thereby posing less of a threat to aquifers. However, when combined with EDTA, a chelating agent found in soaps and laundry detergents, the quantum dots move more quickly through the soil. The study was funded by a $400,000 grant from the United States Environmental Protection Agency for the purpose of learning more about the biodegradation, environmental transport and bioaccumulation of quantum dots and oxide nanoparticles.
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