Ozonolysis of VOCs such as a-pinene has been studied for many years, and it known that byproducts such as gaseous oxidation products and fine particles are generated during the ozonolysis. In this study, we continuously measured gaseous products and fine particulates and ozone concentration during a-pinene ozonolysis under coexisting NO. The reactions were performed in fluoroplastic bags which protected light. Vaporized a-pinene and NO gas (balanced with dry air) were mixed in the reaction bag to adjust the a-pinene concentration at 0.7 ppm, and NO concentration in the range of 0 to 0.9 ppm. Then NO-free ozone, which was generated by the UV irradiation of pure air, was introduced to the bag to make the ozone concentration at 0.4 ppm. One outlet of the bag was connected to the proton transfer reaction mass spectrometry (PTR-MS) to measure the gaseous products, and other outlet was connected to the scanning mobility particle sizer (SMPS) to measure the secondary particulates. Ozonolysis reaction found to start immediately after the introduction of ozone into the bag. Simultaneously ozone concentration in another the bag conditioned similarly conditioned was monitored by an ozone analyzer. Decomposition rate of a-pinene and the total number and the mean diameters of the secondary particulates were unaffected by the NO concentration up to 0.6 ppm. When the NO concentration was 0.9 ppm, decomposition rate of a-pinene was considerably reduced, and the number of the generated particulates as well as the mean diameter were reduced. Ozone concentration was rapidly reduced at the initial stage of the ozonolysis with coexisting NO. However, decomposition of a-pinene continued after the depletion of ozone when the initial concentration NO was 0.6 ppm. This result suggests that not only ozone, but also other types of radicals formed by the NO oxidation contribute to the decomposition reaction of a-pinene.

Real time monitoring of byproducts during a-pinene ozonolysis under coexistenting NO

247th National Meeting (2014)

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