Simultaneous removal of SO2, NO and Hg0 by wet scrubbing using urea + KMnO4 solution

A complex absorbent containing urea and KMnO4 was used to investigate simultaneous removal of SO2, NO and Hg0 from flue gas. By focusing on NO, SO2 and Hg0 removal efficiencies, the influences of different types of oxidants, urea concentration, KMnO4 concentration, Hg0 inlet concentration, initial pH, reaction temperature, SO2 and NO concentrations were systematically investigated. The results indicate that urea + KMnO4 solution cleaned up SO2 quite efficiently; the removal efficiency was more than 98%, and slightly affected by reaction conditions. NO and Hg0 removal efficiencies depended primarily on the KMnO4 concentration. Urea concentration, reaction temperature, initial solution pH, SO2 and NO concentrations all had a strong influence on the NO removal, but had a little influence on the Hg0 removal. The inlet concentrations of Hg0 contributed little to the removal of NO and Hg0. Meanwhile the optimal conditions were established, the absorption capacities of NO, SO2 and Hg0 were calculated and the final reaction products in the solution were analyzed under the optimal conditions. This process is a promising method for the simultaneous removal of NO, SO2 and Hg0.