Effects of phase states on reactions of secondary organic materials with chloride

Friday, 19 December 2014: 9:27 AM
Alexander Laskin1, Bingbing Wang1, Rachel E OBrien2, Stephen T Kelly2, John E Shilling1, Ryan Moffet3 and Mary Kathleen Gilles4, (1)Pacific Northwest National Laboratory, Richland, WA, United States, (2)Lawrence Berkeley National Laboratory, Berkeley, CA, United States, (3)University of the Pacific, Stockton, CA, United States, (4)Lawrence Berkeley National Lab, Berkeley, CA, United States
Secondary organic materials (SOM) in atmospheric aerosols are often mixed with inorganic components. Condensed-phase SOM can exist in a liquid, semi-solid, or solid state at different temperatures and RH. We investigated the effects of phase states of SOM on the reactions of SOM from ozonolysis of limonene (LSOM) and α-pinene (PSOM) with NaCl using a set of complementary micro-spectroscopic analyses. SOM can react with NaCl and result in chloride depletion in the condensed phase, release of gaseous HCl, and formation of organic salts. The reactions driven by the high volatility of HCl are attributed to acid displacement by SOM acidic components. Similar reactions can take place in SOM/NaNO3 particles. Glass transition temperatures and viscosity of PSOM were estimated. The results show that the reaction depends on SOM composition, phase state and viscosity, mixing state, and reaction time. The release and potential recycling of HCl and HNO3 from reacted aerosol particles may have important implications for atmospheric chemistry. This reaction can modify particle physicochemical properties, such as the ability to form clouds, and thus may have important atmospheric implications.