The Applications Of Aqueous Solutions Of Protic Triamine-based Ionic Liquid In The Capture Of Sulfur Dioxide

Sulfur dioxide emission is the main cause of acid rain,smog,and other environmental problems.SO2 in the atmosphere is generally emitted from the combustion of fossil fuels.Therefore,the control of SO2 emission from flue gas is the main task of air pollution control.At present,based on renewable absorption process,the development of absorbent with high desulfurization efficiency is the key research direction in the world.Among them,ionic liquids(ILs)have been widely researched because of their high stability and low volatility.According to the features of renewable absorption process,a kind of aqueous solutions of novel protic triamine-based ionic liquid was proposed for efficient SO2 capture.The absorption and desorption capacity of the mixed absorbents,the absorption mechanism,and related thermodynamic parameters were systematically researched by means of experiment,characterization,and theoretical calculation.[PEDETAH][Sulfate],a kind of protic triamine-based ILs,was synthesized and characterized by MS,1H NMR,and IR etc methods and it's thermal stability were investigated by TGA/DSC.The mixed absorbents were synthesized by blending [PEDETAH][Sulfate] with water,and their physical properties were studied.Remarkably,the viscosities of the mixed absorbents are in the range of 1.44-1.85 m Pa s at 25?,which is advantageous to the process of gas-liquid mass transfer.Detailed SO2 absorption experiments were carried out to investigate the influence of some important factors,including temperature(25??40??55?),SO2 partial pressure(0-100 k Pa)and sulfuric acid proportion.It is worth noting that the mixed absorbents showed excellent absorption capacity,especially at low partial pressure.For example,SO2 capacity for [PEDETAH][Sulfate](1:0.5)at 25? is 0.245 mol SO2 per mole IL at 0.1 k Pa and 2.808 mol SO2 per mole IL at 94.3 k Pa.The equilibrium solubilities of SO2 in the mixed absorbents decreased with the increase of sulfuric acid/PEDETA molar ratio and temperature.Besides,the SO2 capacities of ILs mixed with water and organic solvents were investigated.All of the absorbed SO2 could be released easily and completely by the method of heating reflux at 110?.More importantly,the absorbent could be reused for at least five cycles without noticeable changes in both absorption performance and chemical structure.The detailed absorption mechanism demonstrated by infrared spectrum is the sulfurous acid ionization promoted by the reversible protonation of PEDETA.In the end,the p Ka values of PEDETA and related thermodynamic parameters of protonation reactions were determined by acid titration and parameter analysis based on the reaction equilibrium model in g PROMS software.The absorbent combines the advantages of ILs and aqueous solution,and realizes the features of low viscosity,excellent physiochemical properties,good resistance to sulfuric acid corrosion,high ability on deep removal of SO2 and good enough chemical structure and thermal stability,which are key requirements for the SO2 capture using ionic liquids in industrial FGD process.This study provides a new research idea and experimental data for the application of ionic liquids in SO2 capture.