New particle formation from the reactions of ozone with indene and styrene

BRACCO, LARISA L. B.; DÍAZ-DE-MERA, YOLANDA; RODRÍGUEZ, DIANA; ESCALONA, ALBA; RODRÍGUEZ, ANA M.; TUCCERI, MARÍA E.; ARANDA, ALFONSO

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Año: 2019 vol. 21 p. 11214 - 11225

1463-9076

This work reports the experimental study of the ozonolysis of indene in the presence of SO2 and thereaction conditions leading to the formation of secondary aerosols. The reactions have been carried out ina Teflon chamber filled with synthetic air mixtures at atmospheric pressure and room temperature. As inthe case of styrene, SO2 plays a key role in the oxidation of the Criegee intermediates and enhances theformation of particulate matter. Thus, for the ozonolysis of indene, nucleation was observed for reactedindene concentrations above (4.5 0.8) 1011 molecule cm3 in the absence of SO2 while new particleformation was observed for concentrations one order of magnitude lower, (3 1) 1010 molecule cm3,in the presence of SO2. Within the detection limit of the system, SO2 concentrations remained constantduring the experiments. The formation of secondary aerosols in the smog chamber was inhibited by H2Oand so the potential formation of secondary aerosols under atmospheric conditions depends on theconcentration of SO2 and relative humidity. Computational calculations have been performed for theozonolysis of both indene and styrene in the presence of SO2 and water to identify the reaction channelsand species responsible for new particle formation. The release of SO3 and its subsequent conversion intoH2SO4 from the reaction of the Criegee intermediate H2COO in the ozonolysis of styrene makes thisaromatic have a high potential of aerosol formation in the atmosphere. On the other hand, quantitativeconversion of SO2 into SO3 does not occur following the ozonolysis of indene.