Influence of ozone, relative humidity, and flow rate on the deposition and oxidation of sulfur dioxide on yellow sand

To evaluate the influences of O-3, relative humidity (RH), and flow rate on the reaction between yellow sand and SO2, the SO2 deposition velocity and the oxidation state of sulfur were investigated by means of exposure experiments in a cylindrical flow reactor. Early in the reaction, the deposition velocity was not influenced by the RH or the presence of O-3; as the reaction progressed, however, the deposition velocity increased in the presence of O-3 and at high humidity. The oxidation of sulfur from S(IV) to S(VI) was also enhanced under these conditions. The amount of sulfur oxidation was positively correlated with the amount of deposited O-3. Furthermore, the SO2 deposition velocity increased with increasing flow rate. However, changes in the flow rate had no noticeable effect on the amount Of SO2 oxidation. (C) 2004 Elsevier Ltd. All rights reserved.