Generation, Characterization, and Atmospheric Aging of Soot Particles from Diesel Combustion

0932705

Zhang

Soot aerosol produced from diesel combustion represents one of the major forms of particulate matter pollution, profoundly impacting human health, weather, and climate. However, few experimental studies have been carried out to investigate their transformation and associated variations in chemical and physical properties, because of difficulties in generation and sampling of diesel soot particles under controlled laboratory conditions. In this project, a novel approach using a shock tube is explored to generate soot to mimic diesel-engine combustion. Laboratory experiments are designed to simulate atmospheric aging of diesel soot aerosols by exposure to condensable gas-phase species (such as sulfuric acid and carboxylic acids) and semi-volatile organic compounds generated from oxidation of anthropogenic and biogenic volatile organic compounds. The changes in morphology, hygroscopicity, and optical properties of diesel soot aerosols during internal mixing are measured using a suite of aerosol analytical instruments.

The research is expected to provide important information on the particle mass-size relationship, internal mixing of soot with atmospherically important inorganic and organic species, and variations of hygroscopicity and optical properties of diesel soot during atmospheric aging. Results generated from this proposed research can benefit experimental studies, model simulations, and ambient measurements of soot-containing aerosols. The results on chemical and physical properties of soot aerosols can be incorporated into atmospheric models to evaluate their effects on weather and climate. The information on the morphology and chemical compositions of soot aerosols can also be employed to assess human-health effects including respiratory and cardiovascular diseases.

A better understanding of production and atmospheric transformation of soot aerosols helps to reduce uncertainties in climate prediction and assessment of human health effects, which are important for development of control strategies. Hence, this research is expected not only to advance our knowledge of generation, transformation, and chemical compositions and contribute to improved model simulations and ambient measurements of soot aerosols, but also to be beneficial to the public by identification of potential health issues and to policy decision-makers for development of effective particulate-matter control strategies. The multidisciplinary nature of this project combines expertise of combustion researchers and atmospheric aerosol chemists. The project provides interdisciplinary research opportunities for undergraduate students, graduate students, and post-doctoral researchers in the areas of mechanical engineering and atmospheric sciences. They are expected to present their work at conferences and build connections within the two scientific communities as part of their education and training on global environmental change research.