Join us for the next Energy and Environment seminar at the Powerhouse! This event will be held from 1-2pm in the Powerhouse Classroom 104
Info on the seminar:
"Diesel exhaust particles (DEP) are air pollutants that adversely affect air quality and human health. DEPs have been shown to be semi-volatile and hence partition between the gas and particle phases in the atmosphere. DEPs, additionally, are also very reactive and can directly or indirectly lead to the formation of reactive oxygen species through their interaction with human cells. The volatility and oxidative reactivity properties of DEPs are not well understood and particularly uncertain when it comes to alternative fuels and modern emissions control devices.
In this study, we measured DEPs from a modern-day non-road diesel engine for two different fuels (conventional diesel and soy-based biodiesel), two different engine loads (idle and 50% load), and with and without an emissions control device at approximately eight different dilution ratios. DEPs were collected on a combination of bare quartz, Teflon, and quartz behind Teflon filters. Differences between the bare quartz and quartz behind Teflon filters were used to infer the volatility distribution of the organic mass fraction of the DEPs. The oxidative reactivity was measured by performing a dithiothreitol (DTT) chemical assay on DEPs extracted in water and an organic solvent.
The estimated volatility distribution did not change with fuel, engine load, or emissions control device. In contrast, the oxidative reactivity of DEPs from the use of diesel fuel seemed to be higher (~factor of 3) than that for biodiesel fuel. The use of a diesel particle filter (DPF), which is an emissions control device, significantly reduced (~factor of 10) the oxidative reactivity of DEPs. Finally, the oxidative reactivity measured for DEP’s extracted in an organic solvent was higher by a factor of 2, when compared with a water extract.
This research directly addresses the individual effects of fuel, engine load, and emissions control devices on the atmospheric and health-relevant properties of DEPs. Ongoing work is focused on modeling the evolution of the DEP abundance and oxidative reactivity in the atmosphere."