The Compaction of Spark Discharge Generated Soot Particles in Toluene/NOx/air Photooxidation System

摘要

Soot, which is generated from biomass burning and the incomplete combustion process of fossil fuel, is an important component of atmospheric aerosols1. Besides visibility reduction and the adverse effects to public health, the soot particles have some unique effect on the environment. For example, soot particles can absorb solar radiation very efficiently due to the high black carbon (BC) content, and thus give rise to significant positive climate forcing2. Generally, soot particles exhibit ramified and apparently irregular agglomerate structure, which contains a number of small roughly spherical elementary particles3. It is recently reported that the fractal agglomerates can collapse to a more compact structure by coating with secondary organic aerosol (SOA) generated from the α-pinene ozonolysis system4, . This 5 shrinking was proposed to be caused by the capillary forces of condensed organic matter in the small angle cavities of the agglomerates4, . Since the compaction directly changes the 5 surface properties and the size distribution of soot particles, it is expected to induce important changes to the soot particles' physical and chemical properties (e.g. hygroscopic, optical and catalytic properties).^