The Influence of Iron on Ammonium Ion Generation from Nitrate Ion in Liquid Phase

摘要

Flue gas cleaning in discharge plasma process has been studied intensively and we have tried to remove the NOx and SO2 using the wet-type plasma reactor. In this system, NO is oxidized to NO2 and absorbed as NO-3, and SO2 is absorbed as SO32- and oxidized in the liquid to SO42-. But the concentration of NO-3 was saturated and the absorption of NOx and SO2 was inhibited. Then, the reduction of NO-3 in the liquid is required. We examined the reductive reaction of NO-3 to NH4+ using discharge above the liquid surface then the pH value of the liquid was changed to alkaline slightly. When the Fe plate was used as a ground electrode in the liquid,NH4+ was generated. Then, the relation between the generation of NH4+ and Fe ions (Fe2+ and Fe3+) was studied. When Fe2+ was presented in the liquid, NH4+ was generated and Fe2+ was oxidized to Fe3+. Fe2+ is required to generate NH4+ from NO-3. When NH4+ was generated from NO-3, both the calculated pH value from NH4+ concentration and the measured pH value indicated a similar value. From these results, the discharge above the liquid surface was effective to convert NO-3 to NH4+ and the reductive reaction leads to more absorption of NO-3. These results showed that the wet-type plasma reactor is effective for NOx and SO2 removal system.