NO3- reduction for flue gas cleaning using wet-type plasma reactor

Fundamental characteristics of the flue gas cleaning for NO x using the wet-type plasma reactor has been evaluated, with attention being laid on concentration of nitrate and ammonium ions in the liquid. The wet-type plasma reactor was a wire-cylinder, driven by square wave high voltage pulse. A thin liquid film was maintained on the inner wall of the reactor. In this reactor, discharge plasma oxidizes NO to NO 2 , and NO 2 is dissolved into the liquid as HNO 3 . Continuous absorption induces saturation and acidification of the liquid, inhibiting the absorption of NO x . Effect of the NH 3 addition for enhancement of NO x removal has been experimentally confirmed. The NH 3 addition was effective for NO oxidation as well as NOx absorption into the liquid, resulting in the increasing of NO 2 - and NO 3 concentration in the liquid. With the presence of Fe ions in liquid exposed to the discharge plasma, reduction can be made from NO 3 - to NH 4 + through the oxidation of Fe 2+ to Fe 3+ . The reductive reaction enhances the absorption of NO x . These results suggest the possibility of the continuous operation of the wet-type plasma reactor for NO x removal without excess acidification of the absorbing water, nor feeding additives.