Absorption Of Nitric Oxide From The Flue Gas By Aqueous Solutions Of Ferrous Sulfate Combined With Sodium Sulfite

China, the world’s largest country of coal manufacture and consumption, the emission of exhausted gases produced by the combustion of coal fuels, particularly, nitrogen oxides(NOx), has caused quite serious environmental issues, like photochemical smog, acid rain, depletion of the ozone layer. Selective Catalytic Reduction (SCR) is one of the conventional technologies for the removal of NOx, nevertheless, it has many drawbacks, like relatively high operational cost, the risk of secondary pollution and catalyst poisoning. Wet scrubbing process of NOx seems to be a promising method because of its easy control and slight improvement of the flue gas desulfurization (FGD) equipment can achieve simultaneously removal of SO2and NOx. In this paper, we mainly select ferrous sulfate combined with sodium sulfite as the absorbents to research their denitrification performance, and the main works were shown as follows:(1) Investigated and calculated the thermodynamic parameters of the system at different temperatures, to theoretically verify the feasibility of the absorbents for denitrification. The results show that the reaction between NOx and absorbents is controlled by liquid film and it can happen spontaneously, in addition, the reaction is exothermic, rising temperature is not conductive to the increase of NO removal efficiency;(2) All experiments were studied in a self-designed bubble reactor. Firstly, we verified the feasibility of the absorbents for denitrification by experiments, and then, the main factors affecting NO removal efficiency were prioritized by orthogonal experiments, afterward, the main influencing factors on NO removal efficiency were investigated by the single factor experiments. The experimental results show that NO removal efficiency could reach83%in the absorbents under the optimal experimental conditions:inlet gas flow rate of100ml/min, reaction temperature of30℃, the pH value of6, O2concentration of6%(v/v), and concentrations of Na2SO3and FeSO4of0.07mol/L and0.1mol/L, respectively. Finally, we employed Raman spectrum to characterize the ions in the solutions and then revealed the mechanism of denitrification for the system;(3) Investigated regeneration of solutions by iron. The experimental results show that the more iron, the faster stirring speed, the higher NO removal efficiency for the regenerated solutions. After5times regeneration, the solutions can have50%of NO removal efficiency.