HETEROGENEOUS POLYCYCLIC AROMATIC HYDROCARBON DEGRADATION WITH OZONE ON SILICA-GEL CARRIER

Heterogeneous degradation of five polycyclic aromatic hydrocarbons (PAHs), perylene (Pe), pyrene (Py), benzo[a]pyrene (BaP), benz[a]anthracene (BaA), and fluoranthene (Flo), adsorbed on nonactivated (moisture-containing) silica gel with ozone in a fluidized-bed reactor has been studied. The concentrations of ozone employed varied from 0.050 to 0.400 ppm. The results obtained show that, concerning their kinetics, there is a clear difference between reactions with less than and more than monolayer coverage of the particle surface with PAHs, those carrying a submonomolecular layer being faster and indicating the effect of the particle surface. In more highly covered samples, the observed degradation obeys two distinct first-order laws, the slow one changing into the faster at monomolecular coverage; the relative reactivities are as follows: Pe > BaP > BaA > Py >> Flo, and BaP > Pe > BaA > Py >> Flo, respectively. According to the present results, heterogeneous degradation of PAHs by ozone on particle surfaces is one of important pathways for their removal from the atmosphere.; Heterogeneous degradation of five polycyclic aromatic hydrocarbons (PAHs), perylene (Pe), pyrene (Py), benzo [a]pyrene (BaP), benz[a]anthracene (BaA), and fluoranthene (Flo), adsorbed on nonactivated (moisture-containing) silica gel with ozone in a fluidized-bed reactor has been studied. The concentrations of ozone employed varied from 0.050 to 0.400 ppm. The results obtained show that, concerning their kinetics, there is a clear difference between reactions with less than and more than monolayer coverage of the particle surface with PAHs, those carrying a submonomolecular layer being faster and indicating the effect of the particle surface. In more highly covered samples, the observed degradation obeys two distinct first-order laws, the slow one changing into the faster at monomolecular coverage. Additional aspects of the study are discussed.