Removal Of Nitric Oxide From Flue Gas In Aqueous Solution Accompanying Air Oxidation And Reduction With Iron

The nitrogen oxides is one of the major air pollutants,It is very harmful to human healthand to the environment hazards.90percentage nitrogen oxides in the combustion flue gas arewater-insoluble nitric oxides. A new method was proposed for regeneration of nitric oxidesabsorption product from FeⅡEDTA complex process, in which FeⅡEDTA(NO) was desorptedby air oxidation and FeⅢEDTA was reduced by Fe powder.This method can achieve theobjective of low cost and high efficiency removal of nitric oxides and effectively recoverednitrogen dioxides resources.First of all, the method of this experiment is use FeⅡEDTA for the absorbtion liquid, NOabsorption experiments in the bubble column,then NO desorption and oxidation from FeⅡEDTA(NO) by air oxidation was performed in a pressurized reactor.To make it clear all thelikely influential factors,we have investigated the following factors,such as temperature andair pressure.Experimental results we have gained can be shown as, the desorption efficiency,increases with the increase of temperature.As is known,the process of NO desorption is anendothermic process.Besides,with the increase of the air pressure,the concentration gradientof O2gas-liquid mass transfer tends also to increase,which should be considered propitious tothe oxidation of FeⅡEDTA.The results show that when the pressure is0.4MPa,temperature is333K,the process for the oxidation of FeⅡEDTA is completely to accomplish,while NO2/NOxpercentage can reach90%.Furthermore,FeⅢEDTA can be effectively regenerate into FeⅡEDTA by iron powder in astirred tank at laboratory condition.This paper mainly studied several factors that affect theefficiency of reduction,such as temperature、pH、oxygen content、stirring rate、quality of Fepowder and so on.The results showed that the optimum operating conditions were asfollows:pH=6, temperature is333K, oxygen content2.1%, stirring rate600rpm,0.8g Fepowder.Absorption efficiency of NOxin bubbling tower is the largest, up to99.1%.Finally, this reabsorption experiment is use FeⅡEDTA for the absorbtion liquid,NOabsorption experiments in the bubble column.This paper mainly studied several factors thataffect the efficiency of reduction,such as temperature、pH、oxygen content and so on.Theresults showed that the absorbtion liquid is much more easily influenced by pH.When the pHof absorbtion liquid is less than7,absorption efficiency of NOxup to90%.When the pH ofabsorbtion liquid is8and10, absorption efficiency of NOxdown to58.6%and31.5%.Theoptimum operating conditions were as follows:pH=6, temperature is333K, oxygen content2.1%,absorption efficiency of NOxin bubbling column is the largest, up to90%.