Removal of NOx, SO2, and Hg From Simulated Flue Gas by Plasma-Absorption Hybrid System

The simultaneous removal of NOx, SO2, and Hg from simulated flue gas by a plasma-absorption hybrid system was investigated. In the nonthermal plasma reactor, NO could be effectively oxidized to NO2. However, Hg-0 oxidation was significantly restrained since NO concentration and its reactivity with O-3 are much higher than those of Hg-0. In the absorber, SO2 and NO2 were absorbed by (NH4)(2)SO3 solution, in which the S(IV) ions (SO32- and HSO3-) were found to be dominant for NO2 absorption. The S(IV) ions were significantly oxidized during the absorption, causing an increase in NO2 concentration with operating time. However, the addition of S2O32- inhibited the S(IV) oxidation and promoted the removal of NO2. With a followed electric mist eliminator, the NH3 slipped from the absorber can be captured, and Hg-0 was efficiently oxidized, which can be further removed by water absorption.