Optical Study Of OH Radicals Produced By DC Corona Discharge

DC corona discharge plasma has been widely used in the removal of acid gases from fluesgas, the removal of organic compound, disinfection and sterilization, dissociation of VOCsand other toxic pollutant. The active spices produced by the corona discharge play importantrole in the removal process. Especially, OH radicals with their stronger oxidation play thecentral role in many physicochemical processes. In this article, for the purpose of removalSO₂/NOx from coal burning power plant, coal burning industrial boiler, coal burning furnacesand so on, the OH radials produced by positive and negative DC corona discharge in N₂ andH₂O mixture gas in a needle-plate reactor are studied by emission spectra technology. Themain research results as fallows:â… . The emission spectra of OH (A²âˆ‘→X²ÐŸ, 0-0) radicalsThe emission spectrum of OH (A²âˆ‘→X²ÐŸ, 0-0) and N₂ (C³ÐŸ_u→B³ÐŸ_g) molecule emittedfrom the positive and negative DC corona discharge of N₂ and H₂O mixture gas in aneedle-plate reactor at atmospheric pressure is successfully recorded.â…¡. The calculation of the relative population of the OH radicalsTheâ–³v=+1 vibration transition band of N₂ (C³ÐŸ_u→B³ÐŸ_g) and the emission intensity ofOH (A²âˆ‘→X²ÐŸ, 0-0) is seriously overlapped, so the relative vibration population of N₂(C,v') are obtained by the emission intensity of theâ–³v=-3 andâ–³v=-4 vibration transitionband of N₂ (C3П_u→B³ÐŸ_g). The emission spectrum of theâ–³v=+1 (1-0, 2-1, 3-2, 4-3)vibration transition band of N₂ (C³ÐŸ_u→B³ÐŸ_g) is simulated through gauss distribution. Theemission intensity of OH (A²âˆ‘→X²ÐŸ, 0-0) has been exactly gotten by subtracting theemission intensity of theâ–³v=+1 vibration transition band of N₂(C³ÐŸ_u→B³ÐŸ_g) from theoverlapping spectra. The relative population of OH (A²âˆ‘) can be obtained by the emissionintensity of OH (A²âˆ‘→X²ÐŸ, 0-0).â…¢. The effect of the polarity of the needle electrode and the addition O₂/He into the N₂ andH₂O mixture gas on the emission intensity of OHIn the N₂ and H₂O mixture gas in the negative DC corona discharge, the relativepopulations of OH(A²âˆ‘) radicals and the N₂(C³ÐŸ_u) molecule increase with increasing thedischarge voltage and input power, and decrease with the addition of the O₂. In the positiveDC corona discharge, the emission spectrum of N₂ (C³ÐŸ_u) molecule is weaker than in the emission spectrum of N₂ (C³ÐŸ_u) molecule in the negative DC corona discharge, and theemission spectrum of OH (A²âˆ‘) radicals do not been abtained.In the N₂ and H₂O mixture gas in the negative DC corona discharge, the relativepopulations of OH(A²âˆ‘) radicals and the N₂(C³ÐŸ_u) molecule increase with the increasing ofdischarge voltage and input power, but the relative populations of OH(A²âˆ‘) radicals and theN₂(C³ÐŸ_u) molecule do not change with the addition of He in our probe region. In positive DCcorona discharge the shape of the corona is like a pillar, and the length of the pillar increaseswith increasing the discharge voltage, but the illumination of the corona is stable. The relativepopulation of OH (A²âˆ‘) radicals produced by per unit power increases with the addition of Heand decreasing the discharge voltage.