Removal of NO from flue gas by wet scrubbing with NaClO2/(NH2)2CO solutions

The experiments were performed in a countercurrent packed column in a continuous mode to study the absorption of nitric oxide in sodium chlorite/urea solutions. Sodium chlorite mainly works as an agent to oxidize NO to NO2. A combined SO2/NO removal system was also tested. On the basis of high SO2 removal efficiency, the NO removal efficiencies under various experimental conditions were emphatically measured. Among the operating variables such as initial NaClO2 concentration, urea concentration, temperature and initial pH value, the pH value of the absorbing liquid was found to have a great impact on both NO removal efficiency and NO2 concentration. NO removal efficiency was increased with increasing NaClO2 concentration and temperature. Urea almost has no negative effect on NO removal efficiency, however it aids the abatement of NO2 greatly. The anions in the spent scrubbing liquor were analyzed by ion chromatography.