The Chemical Fate of Sulfur in Thiophene against Nitrate Radical Oxidation
MICHAEL LUM, Kunpeng Chen, Alexander B. MacDonald, Nilofar Raeofy, Raphael Mayorga, Haofei Zhang, Roya Bahreini, Ying-Hsuan Lin,
University of California, Riverside Abstract Number: 153
Working Group: Aerosol Chemistry
AbstractThiophene is a sulfur-containing volatile heterocycle emitted during the combustion of biomass. While current literature has reported the formation of secondary organic aerosol from nighttime oxidation of organosulfur compounds, the transformation of S-containing volatile organic compounds (VOCs) leading to the production of organic and inorganic sulfate, as well as non-sulfate sulfur in atmospheric aerosols is less studied. This study intends to use thiophene as a model compound to investigate how such compounds contribute to formation of organosulfate and inorganic sulfate in aerosols. Thiophene was oxidized by nitrate radicals in a 10 m
3 environmental chamber, under NOx/ozone ratios of 0.1 and 0.3 to simulate various levels of the NO
3 oxidant. The fate of sulfur under these conditions will be explored using the following techniques: (1) the resulting inorganic sulfate to organosulfate ratios will be determined through ion chromatography (IC) and aerosol mass spectrometry; (2) oxidation state of sulfur in S-containing molecules will be obtained through X-ray photoelectron spectroscopy; and (3) the molecular composition and structures of the resulting organosulfur and organosulfate compounds will be determined through high-resolution mass spectrometry. Organosulfur and inorganic sulfate aerosols both have significant climatic implications in the atmosphere. Oxidation of thiophene and other sulfur-containing VOCs could prove to be an important, currently unaccounted for, source of these two atmospheric pollutants of interest.