Atmospheric aerosols have profound impacts on air quality, the global climate, and public health. Those derived from organic sources constitute a significant portion of particulate matter in the atmosphere and readily react with tropospheric ozone. The carbonaceous ozonolysis products that form from the heterogeneous ozonolysis of d-phenothrin behave and react differently than their pesticide precursors, further complicating climate systems. Additionally, the hygroscopic properties of d-phenothrin and its oxygenated aerosols play a significant role in the condensation of water vapor in the atmosphere, thus influencing light scattering properties and cloud droplet formation. Heterogeneous interactions between d-phenothrin thin film and gaseous ozone were investigated using a flow reactor coupled to attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) under various conditions of temperature, humidity, and ozone concentration. The apparent pseudo-first-order rate constant (kapp) of 100 µL of 3mM d-phenothrin thin film ~0.2 µm thick plateaued at 0.175 s-1 at 8.89x104 ppb ozone concentration. Additionally, interactions with ozone produced a 2-fold increase in the hygroscopicity of the ozonolysis products over the d-phenothrin thin film. Establishing ozonolysis reaction rates and hygroscopic properties of d-phenothrin and its ozonolysis products enables the incorporation of anthropogenic aerosol degradation into atmospheric chemistry models.

Kinetic and hygroscopic study of phenothrin oxidized by ozone using an ATR-FTIR flow reactor

ACS Spring Meeting 2021

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