Experimental Study of the Formation of Organosulfates From α-Pinene Oxidation. Part II : Time Evolution and Effect of Particle Acidity

Abstract The present work is an extensive laboratory study of organosulfate (OS) formation from the reaction of α-pinene oxidation products or proxies with acidified ammonium sulfate aerosols in three different acidity conditions ((NH4)2SO4 0.06 M; (NH4)2SO4/H2SO4 0.06 M/0.005 M; (NH4)2SO4/H2SO4 0.03 M/0.05 M). The kinetics of the reactions of α-pinene, α-pinene oxide, isopinocampheol, pinanediol and myrtenal with ammonium sulfate particles were studied using a quasi-static reactor. The reaction of α-pinene oxide with the highly acidic ammonium sulfate particles was determined to be 7, 10, 21 and 24 times faster than for isopinocampheol, α-pinene, pinanedial and myrtenal, respectively for an OS precursor concentration of 1 ppm and after 1h reaction time. The effective rate coefficients for OS formation from α-pinene oxide were determined to be two orders of magnitude higher in highly acidic conditions than for the two other acidity conditions. For α-pinene oxide reactions with highly acidic ammonium sulfa...