Heterogeneous interaction of peroxyacetyl nitrate with liquid sulfuric acid

The uptake of peroxyacetyl nitrate (PAN) on liquid sulfuric acid surfaces has been investigated using a fast-flow reactor coupled to a chemical ionization mass spectrometer. PAN was observed to be reversibly adsorbed on sulfuric acid. From the time-dependent uptake, Henry's law solubility constant of PAN in sulfuric acid was obtained. The measured solubility constant was found to depend strongly on temperature (199-226 K), but weakly on acid composition (46-72 wt %). On 72 wt % H2SO4, for example, the effective Henry's law solubility constant was determined to be about 5.6 x 10(4) and 3.1 x 10(3) M atm(-1) at 208 and 222 K, respectively. Heterogeneous reactions of PAN with HCl, Cl, ClO, and OClO on liquid sulfuric acid were also investigated and found to be very slow (gamma < 1 x 10(-4)). Atmospheric implications of the present results are discussed.