Reaction of SO2 with sodium chlorate powder triggering oxidation of NO and Hg0

This study investigated the reaction of powdered sodium chlorate (NaClO3(s)) with air pollutants. 200 ppm SO2, 200 ppm NO, and 260 μg/N m3 Hg0 in 2.6 L/min of N2 balance were introduced into a reactor containing 2.4 g of NaClO3(s). Results showed that SO2 has reacted exclusively with NaClO3(s) to produce Na2SO4(s) above 220 °C, whereas NO and Hg0 themselves have no reactivity toward NaClO3(s). However, oxidation of NO and Hg0 occurred when they were introduced with SO2 into the reactor containing NaClO3(s). NO2 as a radical scavenger was introduced at the forward and backward positions of reactor to determine which species are responsible for the oxidation of NO and Hg0 during the reaction of SO2 with NaClO3(s), where ClONO2, ClNO2, and OClO species were observed. Kinetic simulations were also conducted to elucidate reactions between chlorine species, where final products were nearly Cl2 on both OClO + Cl and OClO + ClO reactions when reaction time was 2.4 s. These suggest that OClO, ClO, and Cl generated during the reaction of SO2 with NaClO3(s) can oxidize NO to NO2 and Hg0 to Hg2+.

► Reaction of NaClO3(s) with SO2, NO, and Hg0 has been investigated.
► SO2 has reacted with NaClO3(s) above 220 °C.
► No reactivity of NO and Hg0 with NaClO3(s) has been observed.
► However, in the presence of SO2, NO and Hg0 have been oxidized.
► This is caused by Cl-containing species generated during the reaction of SO2 with NaClO3(s).