Disposal of waste through incineration produces hazardous pollutants. Among them, polycyclic aromatic hydrocarbons (PAHs) and chlorinated dioxins and furans are of concern, as some of them can induce cancer, can cause mutations in genetic material, and can interfere with the proper functioning of hormones. In addition, some of these compounds can remain in the environment for a long time and be transported long distances from where they were originally released.
Abstract figure from Vejerano et al. 2013*
Disposal of nanomaterials is inevitable, and some of them will be incinerated. How nanomaterials interact with waste during incineration and their influence on pollutant formation, however, are not yet understood. The small size of nanomaterials and their large surface area may enhance the formation of hazardous pollutants.
To this effect, Dr. Eric Vejerano, a post-doctoral researcher associated with CEINT, and Dr. Linsey C. Marr, a CEINT faculty member, have conducted laboratory incineration studies of paper and plastic wastes containing nanomaterials. The emissions of smaller PAHs were enhanced in waste containing nanomaterials. PAH emissions were ~6 times higher for the nanomaterials compared to their bulk counterparts. Chlorinated dioxins were not detected in the presence and the absence of the nanomaterials. However, among the different nanomaterials, silver and titania increased the emissions of chlorinated furans. This result is of concern as these two nanomaterials are produced and used in greater quantities compared to the others. Pollutant emissions were affected by both the surface area and by the type of the nanomaterials.
Some of these hazardous pollutants will be removed from incinerator exhaust by air pollution control equipment, but open burning, which is practiced in some areas, could lead to their release into the environment. As nanomaterials are used in more and more consumer products, further studies on their environmental and health impacts are warranted.
*Vejerano, Eric P., Holder, Amara L., Marr, Linsey C. Emissions of Polycyclic Aromatic Hydrocarbons, Polychlorinated Dibenzo-p-Dioxins, and Dibenzofurans from Incineration of Nanomaterials. Environmental Science & Technology.