Nitric oxide removal by combined urea and FeHEDTA reaction systems

(NH2)(2)CO as well as Fe(II)EDTA is an absorbent for simultaneous desulfurization and denitrification. However, they have their own drawbacks, like the oxidation of Fe(II)EDTA and the low solubility of NO in urea solution. To overcome these defects, A mixed absorbent containing both (NH2)(2)CO and Fe(II)EDTA was employed. The effects of various operating parameters (urea and Fe(II)EDTA concentration, temperature, inlet oxygen concentration, pH value) on NO removal were examined in the packed tower. The results indicated that the NO removal efficiency increased with the decrease of oxygen concentration as well as the increase of Fe(II)EDTA concentration. The NO removal efficiency had little change with a range of 25 45 degrees C, and sharply decreased at the temperature of above 55 degrees C. The NO removal efficiency initially increases up to the maximum value and then decreases with the increase of pH value as well as the raise of urea concentration. In addition, the synergistic mechanism of (NH2)(2)CO and Fe(II)EDTA on NO removal was investigated. Results showed that urea could react with Fe EDTA-NO to produce Fe(II)EDTA, N-2, and CO2, and hinder oxidation of Fe(II)EDTA. Finally, to evaluate the effect of SO32- on NO removal, a mixed absorbent containing Fe(II)EDTA, urea, and Na2SO3 was employed to absorb NO. The mixed absorbent could maintain more than 78% for 80 min at 25 degrees C, pH = 7.0, (NH2)(2)CO concentration of 5 wt%, Fe(II)EDTA concentration of 0.02 M, O-2 concentration of 7% (v/v), and Na2SO3 concentration of 0.2 M. (C) 2016 Elsevier Ltd. All rights reserved.