The gas-liquid two-phase enhanced denitrification experiments are carried out in a packed tower by using gaseous NO_2 and solid MnO_2.NO_2 is mixed into the simulated flue gas to enhance the degree of oxidation and strengthen the dissolution of NO gas into absorption solution.MnO_2 is mixed into the dilute nitric acid to oxidize on time the absorbed products into manganese nitrate.The effects of MnO_2 concentration,oxidation degree of NO_x,reaction temperature,initial pH value of the absorption solution,rat...