10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Generating Biodiesel and Fossil Diesel Exhaust Particles with Varied Physico-Chemical Properties for Toxicological Studies
LOUISE GREN, Vilhelm B. Malmborg, Pravesh C. Shukla, Sam Shamun, Christina Isaxon, Per Axel Clausen, Martin Tunér, Ulla Vogel, Joakim Pagels, Ergonomics and Aerosol Technology, Lund University, Sweden
Abstract Number: 853 Working Group: Aerosols and Health - Connecting the Dots
Abstract Introduction Diesel exhaust (DE) is classified as carcinogenic and is suspected to play an important role in the adverse effects of ambient PM in urban areas. Candidates for toxicologically relevant particle properties include the specific surface area and surface reactivity of the solid black carbon core, the liquid organic fraction including polycyclic aromatic hydrocarbons (PAHs), and transition metals.
The use of renewable fuels such as rapeseed methyl ester biodiesel (RME) and hydrotreated vegetable oil renewable diesel (HVO) in the commercial and private transport sectors is increasing. The fuels reduce net green house gas and alter health relevant emissions compared to fossil diesel (Murtonen et al., 2009). The largest reduction of emitted PM is attributed to RME, however its oxygenated organic fraction has been linked to increased oxidative potential and higher in-vitro toxicity (Hedayat et al., 2016). The chemical composition of HVO fuel is more similar to fossil diesel , so far the knowledge of its exhaust emissions is limited.
We here describe an approach where the particle composition and properties can be varied over a wider range and in a more systematic way compared to previous studies while maintaining realistic engine operation conditions. Exhaust, from a modern heavy-duty diesel engine fueled by fossil diesel, 100% RME and 100% HVO biodiesel , was characterized and collected to be used in a n in-vivo toxicological study.
Method A six cylinder heavy-duty diesel engine modified for a single cylinder operation was used for the experiment. The engine was run at a fixed engine operating load with varying exhaust gas circulation (EGR). The exhaust gas was sampled after a partial flow dilution tunnel. Exhaust particles were characterized using real-time aerosol mass spectrometry (AMS), a fast mobility particle analyzer (model DMS 500), aethalometer (model AE33), thermal optical analyser (OC/EC) and Transmission Electron Microscopy (TEM). Toxicological studies require large amount of PM (~30 mg). A High Volume Cascade Impactor (HVCI 900, BGI Inc.) followed by methanol extraction and a Versatile Aerosol Concentration Enrichment System (VACES) was used to collect the particles.
Conclusion EGR reduced the amount of O2 and the temperature in the combustion cylinder (a common NOx reduction strategy) . EGR also strongly affected PM emission levels and properties. PM with particle mass fractions ranged from: elemental carbon: 30-80%, organic carbon 20-70% and the PAH/org* fraction: 0.002 - 0.080. The particle size varied with fuel type from 79 (RME)–102 (diesel) nm. Low EGR affected the nucleation mode and CMD.
The collected particles were successfully extracted from the HVCI filters with an extraction efficiency of 85-105%. Currently, a pulmonary exposure study of these particles in mice is in preparation, together with detailed characterization of collected nano material including BET surface area analysis , Reactive Oxygen Species assays and a thorough TEM analysis of the soot micro- and nano structure. The aim of the in-vivo study is to identify relationships between particle physico-chemical properties and biomarkers of genotoxicty, inflammation and cardiovascular effects.
Acknowledgement This work has been supported by AFA Insurance and The Swedish Research Councils FORMAS and VR.
References [1] Hedayat, F., Stevanovic, S., Milic, A., Miljevic, B., Nabi, M. N., Zare, A. ... & Ristovski, Z. D. (2016). Science of the Total Environment, 545, 381-388. [2] Murtonen, T., Aakko-Saksa, P., Kuronen, M., Mikkonen, S., & Lehtoranta, K. (2009). SAE International Journal of Fuels and Lubricants, 2 (2009-01-2693), 147-166.