Simultaneous absorption of NOx and SO2 in oxidant‐enhanced limestone slurry

In this article, a study of simultaneous absorption kinetics of NOx and SO2 in oxidant-enhanced limestone slurry using sodium chlorite as additives is presented. The laboratory-scale experiments were performed in a double-stirred tank reactor, and the effect of inorganic ions and operating parameters on absorption rates was investigated. The results indicate that NOx absorption rate shows a positive order with respect to NO (0.573), SO2 (0.278), and NaClO2 (0.194), whereas SO2 absorption rate shows a first order with respect to SO2 and zero order for both NO and NaClO2 under a typical limestone wet flue gas desulfurization operating condition. Higher pH leads to a decrease of NOx absorption rate but has no significant influence on SO2 absorption. The SO2 absorption rate decreases with the increase of temperature, whereas the NOx absorption rate remains nearly constant. S(IV) in the slurry reduces the NOx absorption rate dramatically and suppresses the SO2 absorption, whereas the presence of nitrate ions can increase the absorption rate of both SO2 and NOx. High concentration of Cl− has a positive effect on the SO2 absorption, whereas it has a negative effect on NOx absorption rate. Additionally, Mg2+ and F− have no impact on SO2 and NOx absorption rates. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1171–1179, 2014