SO2-Enhanced Nitration of Fluoranthene and Pyrene Adsorbed on Particulate Matter in the Heterogeneous Reaction in the Presence of NO2

Heterogeneous photoreaction of fluoranthene (FL) or pyrene (PY) adsorbed on solid support under 10 ppm NO 2 -air in the presence or absence of SO 2 was investigated in order to clarify the effect of SO 2 on nitroarene formation. Formation yield of nitrofluoranthenes (NFs) and nitropyrenes (NPs) were increased by the addition of SO 2 to reaction atmosphere. 1-, 2-, 7-, and 8-NFs were formed in the presence of SO 2 while 1-, 2-, and 7-NF were detected in the absence of SO 2 . After the reaction for 4 h, yield of 2-NF in the presence of 10 ppm of SO 2 was 1.5 times as large as that in the absence of SO 2 . 1-NP and 1,3-, 1,6-, 1,8-dinitropyrenes (DNPs) were formed both in the presence and in the absence of SO 2 . After the reaction for 2 h, yields of 1-NP and DNPs in the presence of 10 ppm of SO 2 were about three times and twice as large as those in the absence of SO 2 , respectively. While the yield of 1-NP and degradation rate of PY were hardly affected by the concentration of SO 2 , the yield of DNPs increased with the increase in SO 2 concentration. The isomer distributions of NFs and NPs indicated that NFs and NPs were formed by non-electrophilic nitration and electrophilic nitration, respectively.