Chemical and optical characterization of aqueous secondary organic aerosol generated by reaction of pyruvaldehyde with sodium sulfite

Organic sulfonates are major constituents and tracers for secondary organic aerosol (SOA). Based on sodium sulfite (Na2SO3) and pyruvaldehyde are main components in aqueous environments, their mixed solution is atomized to simulate atmospheric processes of formation aquous SOA (aqSOA) from liquid aerosol particles rich in Na2SO3 and pyruvaldehyde after water evaporation. Constituents and optics of aqSOA are characterized using mass and spectroscopic instruments in this study. Negative ion mass spectra of aqSOA detected by aerosol laser time-of-flight mass spectrometer appeare strong organic sulfonates' characteristic cleavage peaks of m/z = 32(S−), 48(SO−), 64 (SO2−) and 80(SO3−). UV–Vis spectra of extraction solution for aqSOA existe characteristic absorption peak of organic sulfonate' SO at 210 nm. Peaks of 1140 and 1034 cm−1 in infrared absorption spectra correspond to antisymmetric and symmetric stretching vibration peaks of SO3 group, while, peaks of 830 and 760 cm−1 refer to asymmetric and symmetric stretching vibration absorption peaks of C–S–O. Also, peaks at m/z = 125, 153, 169, 185, 235 and 243 are presented in electrospray ionization negative ion mass spectra of extraction solution. These indicate that 1-hydroxyethane sulfonate and other organic sulfonates are major products of aqueous reaction for Na2SO3 and pyruvaldehyde. Light absorption capacity of aqSOA is remarkably enhanced, mass absorption coefficient averaged in 200–600 nm () for aqSOA is reach to that of biomass burning particles, and gradually raises with increment concentration of Na2SO3. These results can offer experimental basis to study components and optics of organic sulfonates in aerosols under high humidity conditions in polluted areas.