PHOTOCHEMICAL AEROSOL FORMATION FROM AROMATIC-HYDROCARBONS IN THE PRESENCE OF NOX

By using a 4-m3 chamber, photochemical aerosol formation from mixtures of aromatic hydrocarbons (AHCs) and nitrogen oxides (NOx) was studied with the main purpose of determining the aerosol yield. Altogether, 18 aromatic species were investigated, including toluene, xyluene, xylenes, ethylbenzene and methoxybenzene. Evolution of the aerosol was monitored through the measurement of the total number ([CN]) and volume (V) concentrations. Aerosol-forming potential of different aromatics was examined in terms of the maximum growth rates of [CN] and V. By putting dry sheath air into an electrical aerosol analyzer, the net organic volume concentration (Vd) was obtained; then a relation was established between Vd and the C mass concentration, and was used to determine the aerosol yield as defined by the ratio of the particulate C mass to the C mass of the reacted HC. It was found that the yields were larger for toluene, ethylbenzene, and o- and m-ethyltoluene (3.0, 3.1, 3.3 and 3.7%, respectively) but smaller for para-substituted toluene derivatives (< 1.5%). © 1990.