| Sulfur dioxide (SO2) and nitric dioxide (NOx), as the major pollutants of atmospheric, was inevitable causing smog and acid rain, which did harm to human health and environment. Corona discharge was considered as an effective method for the elimination of SO2 and NO from flue gas due to the advantages of simple technology and little resistance loss. However, it had drawbacks of high energy consumption and ammonia escape. It was known that adding metal chelate into the wet scrubbing systems had a high removal efficiency of SO2 and NO. Moreover, metal chelate was deemed to be not consume while realized absorption of SO2 and NO. In this work, corona discharge combined with chemical complex was proposed to remove NO from simulate flue gas in the column reactor, the effects of the water flow rate, the concentration of Co(en)33+ ([Co(en)33+]), supply power voltage, pH, additive, NO concentration and gas flow rate on the removal efficiency of NO were researched. What’s more, the effects of the voltage, the [Co(en)33+], water flow rate, initial NO and SO2 concentration, gas flow rate and initial solution pH on simultaneous removal efficiency of NO and SO2 were investigated. In addition, the products of SO2 and NO removal were analyzed, the mass-transfer model for NO was established, the reaction kinetic process of NO and SO2 removal by chelating was studied. Main conclusions were drawn as follows:(1) Corona discharge combined with chemical complex was proposed to remove NO from flue gas. It was reported that the removal efficiency of NO remarkably increased with the increasing of the supply power voltage, the concentration of cobalt ethylenediamine and the water flow rate. However, the removal efficiency of NO slightly decreased with the increasing of the concentration of NO and the gas flow rate. The pH value had greatly impact on the removal of NO, and the optimum pH for the absorbent of Co(en)33+ and H202/Co(en)33+ was 12.0 and 10.0 respectively. It was found that the cobalt ethylenediamine could greatly enhance the removal efficiency to 70.1% at 25 kV while [Co(en)33+] was 0.02 mol·L-1, which the energy efficiency was up to 23.4 g NO/kWh. The removal efficiency of NO reached to 76.5% at 25 kV when [Co(en)33+] was 0.02 M and [H2O2] was 4.0%.(2) Corona discharge combined with chemical complex was proposed to simultaneous remove NO and SO2 from flue gas. The results showed that the NO removal efficiency increased with the increasing of the voltage, pH, water flow rate and cobalt ethylenediamine concentration, while decreased with the increasing of initial concentration of SO2 and NO and the gas flow rate. The SO2 removal efficiency increased with the increasing of the water flow rate and voltage, while decreased with the increase of the gas flow rate, and nearly unchanged as increasing of initial concentration of SO2 and NO and [Co(en)33+]. In addition, adding Mn2+ and urea into solution could enhance the elimination of SO2 and NO. On the experimental condition, gas low rate at 1.0 m3·h-1, voltage at 25 kV, water flow rate at 80 L·h-1, [Co(en)33+] and [Mn2+] at 0.02 M, [urea] at 2%, the maximum removal efficiency of SO2 and NO could reach to 94% and 68%, respectively, which corresponded to the energy efficiency was 22.2 g NO/kWh and 75.2 g SO2/kWh. The results of products analysis of NO removal with corona discharge indicated that nitrate ion was the predominant product, and simultaneous removal NO and SO2 with corona discharge, the predominant products were nitrate radical ion and sulfate ion. While without corona discharge, the predominant products of NO removal were nitrite ion and nitrate ion, the predominant products of simultaneous removal NO and SO2 were nitrite ion, nitrate ion, sulfite ion, sulfate ion.(3) Based on the double film theory, a novelty formula was established to describe the mass-transfer process for the NO removal efficiency from simulated flue gas by corona discharge combined with cobalt ethylenediamine solution. It was seen that NO removal efficiency increased with the increasing of discharge voltage and the concentration of ethylenediamine solution, slightly increased with the increase in the water flow rate, which were fit to the calculated results of theoretical model.(4)The macroscopic kinetic process of removal NO and SO2 by Co(en)33+ and Mn2+ was researched by experiment, which showed process of reaction can be devided into the fast and slow reaction zone. According to experiment data, reaction order and reaction rate constant, apparent activation energy were calculated in sequence. |
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