KINETIC STUDY OF THE HETEROGENEOUS REACTIONS BETWEEN ADSORBED ANTHRACENE AND OZONE ON ATMOSPHERIC MODEL PARTICLES

摘要

As ubiquitous persistent organic pollutants (POPs), polycyclic aromatic hydrocarbons (PAHs) have attracted much attention due to their allergenic, mutagenic, and carcinogenic properties. Thus, it is very necessary to investigate the fate and lifetimes of PAHs in the atmosphere. In this study, the heterogeneous reactions of ozone with anthracene adsorbed on different mineral oxides (SiO2, α-Al2O3 and α-Fe2O3) and on Teflon disc were investigated in dark at 293 K. Ozone concentration was kept at constant value (1.18×1014 molecules cm-3) during the reaction. Analyses of PAHs samples were performed by a GC-MS. The pseudo-first order rate constants were obtained from the fit of the exponential decay of adsorbed PAH concentrations versus reaction time. The second order rate constants were calculated to be (1.47±0.23)×10-16, (0.99±0.36)×10-16 and (0.73±0.26)×10-16cm3 molecule-1 s-1 on SiO2, α-Al2O3 and α-Fe2O3, respectively, while the highest second order rate constant between anthracene and O3 on Teflon disc was estimated to be 4.83×10-19cm3 molecule-1 s-1. The nature of the substrate determined the lifetimes of anthracene in the atmosphere. These results suggest that the reaction of anthracene with O3 on mineral oxides was much faster than that in gaseous phase, and that mineral oxides can greatly alter the fate of PAHs. They also imply that the role of mineral oxides in the fate of halogenated persistent organic pollutants may be similar to that of PAHs in the atmosphere.