Removal of nitric oxide using combined Fe II EDTA and coal slurry in the presence of SO 2

Abstract

Abstract Nitric oxide was removed by aqueous coal slurry containing FeIIEDTA in the presence of SO2 using a bubbling reactor. The effects of NO and O2 concentrations, temperature and pH on NO removal and coal pyrite leaching were studied. NO removal efficiency and coal pyrite leaching rate increased with the increase of NO concentration. The overall effect of high oxygen concentration is unfavorable to the removal of NO. The reduction rate of the complexed NO by coal pyrite increased with increasing temperature up to 60 °C, resulting in higher NO removal efficiency and coal pyrite leaching rate. Further increase in temperature was unfavorable to NO removal and coal pyrite leaching because the absorption of NO became the rate-determining step. The optimal pH was determined to be about 5.8. When pH was greater than 5.8, the reduction of FeIIEDTA-NO was inhibited, and therefore the NO removal efficiency decreased with further increase of pH. The reduction of FeIIEDTA-NO by coal pyrite played a significant part in coal pyrite leaching. Nevertheless, the leaching of coal pyrite was still controlled by chemical reaction.