By Will Soutter
Nanoproducts will eventually need to be degradable as nanoparticles don’t seem to disappear.
Non-degradable nanoparticles bind to solid residues resulting from the incineration of waste and thus can find their way into the environment. Depicted: the waste incineration plant Emmenspitz. Credit: Tobias Walser
ETH-Zurich researchers belonging to environmental engineering and chemistry fields discovered that cerium oxide nanoparticles do not burn or get modified in waste incineration plants.
Cerium oxide is commonly used in automobile diesel soot filters and catalytic converters. It is a ceramic material with non-toxic properties. This biologically non-degradable material was used for the experiments. As part of the first experiment, cerium oxide particles weighing 10 kg was sprayed onto waste material that was to be burnt in an incinerator at the Solothurn plant that has fly-ash separation and the latest filters. For the second experiment, the scientists sprayed the nanoparticles into the incinerator to simulate a condition of huge nanoparticle release.
During incineration, the cerium oxide particles did not undergo significant change and they stuck on loosely to the combustion residues. These particles were also found in the fly ash. Though these may get filtered, they may affect humans through inhalation, and the food and water cycles.
ETH Zurich chemical engineering professor and head of the study, Wendelin Stark, states that degradable nanoproducts should be the final goal. If these particles are not degradable, they will keep on spreading. The pesticides, ozone-depleting agents, accumulation of plastic and asbestos persist in the environment. These problems can be addressed with degradable nanoproducts.