Study On Removal Of NO From Flue Gas By Metal Ion And Electrochemically Activated PMS

NOx released from burning fossil fuels is considered the primary pollutant in the atmosphere.It is well known that the available control technologies of removing NO including selective catalytic reduction(SCR)and selective non-catalytic reduction(SNCR)processes have the disadvantages of higher capital costs,large occupying area and undesirable problems of high temperatures and disposal of hazardous chemicals.To this end,the more innovative and effective technologies and installations of denitrification have attracted considerable researchers to explore,such as using liquid oxidation reagents with the capable of significantly increasing solubility of NO in liquids.At present,the use of liquid oxidation reagents of Fenton,KMn04,sodium chlorite(NaClO2),and peroxymonosulfate-chemical oxidation processes of NO removal are the popular subject of recent research.This paper first used transition metal ion Fe2+ to activate the PMS system to verify the feasibility of NO removal.Electron spin resonance technology(ESR)and radical quenching experiments were used to verify the types of active species in the system,and then the best experimental parameters were discussed based on the removal effect of NO.The experimental results show that Fe2+-activated PMS can significantly promote the removal of typical gaseous pollutants.The simultaneous presence of SO4·-and ·OH radicals in Fe2+-activated PMS was measured by ESR,and the signals of two radicals were increased when the temperature increased.The intensity also increases.The addition of excess methanol or tert-butanol in the reaction system significantly reduced the removal rate of NO,but did not completely inhibit the removal of NO.This indicates that Fe2+-activated PMS belongs to the novel type of free radical oxidation.Free radical co-oxidation system.At the same time,according to the removal effect of NO,the optimal molar ratio of Fe2+ and PMS at different initial PMS concentrations was 1:1.In addition,the effects of initial solution pH and reaction temperature on NO removal were investigated.The removal of NO from the initial solution pH was significantly reduced due to the precipitation consumption of the catalytic action of Fe2+ and Fe3+ ions and non-radical degradation of PMS.Increasing the initial reaction temperature promotes the removal of NO.In this paper,the absorption kinetics of NO removal by Fe2+/PMS was studied systematically for the first time.The steady-state method was used to determine the reaction order of NO removal.At the same time,the mass transfer reaction kinetic equation was established for the study of oxidation absorption.The conventional mass transfer characteristic parameters,such as interface concentration CNO,i,solubility coefficient H,gas/liquid phase diffusion coefficient D,liquid phase mass transfer coefficient kL,gas phase mass transfer coefficient kG,and phase The boundary area a,at the same time,also studied the basic kinetic parameters such as the reaction rate constant and the chemical absorption enhancement factor.In addition,for the first time,the liquid phase reaction utilization efficiency,liquid solvent critical concentration equation,interface temperature increase and interface stability are studied.These essential kinetic parameters provide a more systematic and comprehensive technology for expanding industrial practice.The performance and kinetics of NO in simulated flue gas by Fe2+activated PMS were studied in depth.The results show that Fe2+ ions have good activation performance and get better performance,NO removal effect.Based on previous research results,the three transition metal ions Fe2+,Co2+ and Fe3+ were compared to activate PMS,and three free radicals were detected by ESR.The signal intensities of SO4·-,·OH and 1O2 are used to confirm the activation properties of the three metal ions.On the basis of this,the effect of three metal ions on the removal of NO by PMS was compared,and the removal mechanism was discussed.New insights were provided for the transition metal synergistic high temperature activation of catalytic PMS.At the same time,the mechanism of free radical oxidation is explored.Based on the characteristics of nitric oxide itself as free radical ·NO,it provides a reference for further exploration and refinement of the reaction pathway between NO and free radical.Electrochemical advanced oxidation technology is widely used to degrade difficult-to-treat organic pollutants.This article takes the lead in using iron/carbon(Fe/Gr)electrodes to activate PMS for the removal of gaseous pollutants NO in flue gas.In addition,electron spin resonance technology(ESR)and free radical quenching experiments were used to verify the types of active species in the system.At the same time,the effect of reaction parameters on NO removal rate under specific Fe/Gr electrode activation PMS conditions was evaluated.The experimental results show:first,it is demonstrated whether the Gr electrode can convert sulfate ions into SO4·-radicals and whether electrons can activate PMS to generate free radicals.Using the type and intensity of free radicals in the ESR electron-magnetic resonance detection system,a radical scavenger is further used to determine the dominant free radicals in the system.The initial PMS concentration,current intensity,initial pH value,commutation period,and in-situ Fe2+ ion and O2 intake gas concentration during the reaction all significantly affected the NO removal rate.In order to test the activation performance of Fe/Gr electrodes,three different electroactivation systems,Fe/Fe,Gr/Gr and BDD/Gr,were also compared.Based on this,the mechanism of Fe/Gr periodic commutation electroactive PMS to remove pollutants was proposed.