Heterogeneous reaction of peroxyacetyl nitrate (PAN) on soot

The interaction between photochemical oxidants and aerosol particles has been examined in previous atmospheric pollution studies. The heterogeneous reaction can affect the concentration of gases and free radicals, as well as the morphology and properties of particles. In this report, the interaction between the photochemical oxidant peroxyacetyl nitrate (PAN) and soot particles was investigated using a flow tube system. We used real-time online monitoring equipment to track changes in PAN concentrations. Substances on the soot surface were detected using ion chromatography (IC), x-ray photoelectron spectroscopy (XPS), and other surface analysis methods. At 295 K, the upper and lower limits of the initial uptake coefficients were 1.28 × 10^-5 and 9.16 × 10^-9, respectively. The heterogeneous reaction of PAN on soot was a first-order reaction to PAN under both dry and wet conditions. The products formed on soot included CH₃COO^-, HCOO^-, NO₂^-, and NO₃^-. With an increase in relative humidity, the production of all species decreased and the relative amounts changed.