10th International Aerosol Conference
September 2 - September 7, 2018
America's Center Convention Complex
St. Louis, Missouri, USA

Abstract View


Does Coal Combustion Emit Siloxane?

ZHAOJIN AN, Wei Zhou, Haixia Ren, Mo Xue, Jianguo Deng, Jingkun Jiang, Tsinghua University

     Abstract Number: 267
     Working Group: Combustion

Abstract
Siloxane is a type of organic polymer widely used in industries for its good thermostability and chemical resistance. It has been reported that siloxane exists in aerosols sampled from ambient air, indoor air, and other sources. Siloxane emitted from carbon conductive silicone tube caused aircrafts in aerosol sampling (Timko et al. 2009, Yu et al. 2009). Siloxane in ambient air samples (Hayden et al. 2008) and coal combustion samples (Schneider et al. 2006) were usually attributed to silicone materials used in the sampling system. In this study, three coal types (bituminous, anthracite, and semicoke coals) were burned in a household stove (NS18-17, 18 kW; Laowan Company; Beijing, China) for heating and cooking. A quartz filter based comprehensive two-dimensional thermal desorption aerosol GC/MS (QF-2D-TAG) were to characterize siloxane emission. A home-made particle size distribution measurement system (PSD) (Liu et al. 2016) was used to measure aerosol in the range of 3 nm to 10 μm. Carbon monoxide and carbon dioxide were monitored to estimate the combustion efficiency of the stove.

In the QF-2D-TAG, organic aerosol was first sampled by the quartz filter in the collection and thermal desorption (CTD) cell. The sample was then heated to 300°C and delivered into the first dimension column for separation based on their boiling points, and a modulator periodically trapped analytes eluting from the first column, and periodically released them into the second column for separation based on their polarity. In-situ hourly measurement of molecular level organic species was realized. Compared to the first thermal desorption aerosol GC/MS-FID (TAG) (Williams et al. 2006) and SV-TAG (Zhao et al. 2013) for measuring semi-volatile compounds, a quartz filter based CTD cell and a comprehensive two-dimensional modulator was used for the QF-2D-TAG.

Molecular level siloxane was measured during a complete residential coal combustion process. Siloxane were largely detected in ignition and fierce combustion stages (Zhou et al. 2016) and (SiOC2H6)6 was one of the most abundant species. More siloxane was detected at higher combustion temperature. Only metal tubing was used in the coal combustion system and the sampling and measurement system to avoid artifacts from carbon tubing.

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