Nitric oxide removal from flue gas by ferrate(VI)/urea solutions

In this work, nitric oxide absorption process by using ferrate(VI)/urea was proposed. The respective influences of the four factors including pH value, ferrate(VI) concentration, urea concentration, and the temperature and the interactive function of them on nitric oxide absorption were investigated with the response surface methodology (RSM) by central composite design (CCD). The proposed model system showed good consistency with the experiment results, by a correlated coefficient (R²) of 0.9875. In addition, the interactive influences between any two variables were elaborated through analysis of response surface. The optimal parameters were found at pH of 7.1, reaction temperature of 43.8 °C, urea concentration of 6.3 wt%, ferrate(VI) concentration of 4.4 mmol/L for 85.2% NO absorption. Finally, N-containing product analysis shows that nitric oxide was primarily transformed to N₂ and NO₃⁻.