| Amine wet flue gas desulfurization can recover sulfur. Adopting the simulated flue gas, the better absorbents formulation and the optimal absorption and desorption conditions of SO2 were studied with amine solutions. The oxidation kinetic equations of ethylenediamine solution were presented through the mothod of series rate. A series of hydroxyl ammonium ionic liquids were synthesized by water-bath microwave. The appropriate absorption and desorption conditions were obtained. The SO2 absorption process with ILs was summarized using structural characterization.Firstly, the absorption and desorption of SO2 experiments were carried out in a batch apparatus by serotonin, hindered amines, hydramine and ethylenediamine. The results showed that ethylenediamine has high SO2 absorption capacity and good desulfurization efficiency. Adding acid additives, SO2 available absorption capacity sharply increases and the anti-oxidation of the absorbents enhances. In ten cycles, the mean desulfurization efficiency of ethylenediamine/boric acid and ethylenediamine/phosphoric acid absorbents was 99%. The desorption efficiency of SO2 was over 90% in the latter nine cycles. The removal of SO2 with ethylenediamine can be intensified by adding boric acid and phosphoric acid. The experimental results showed that ethylenediamine/boric acid solution has higher SO2 available absorption capacity and better oxidation resistance. The suitable conditions for SO2 absorption with ethylenediamine/boric acid solution were following:absorption temperature was 30℃, the initial concentration of ethylenediamine was 0.3 mol·L-1, pH value of the absorbent was about 8.5. The appropriate desorption temperature was 103℃, and desorption time was 60 min, the initial pH value of SO2-absorbed absorbents was 5.50±0.15.Secondly, the continuous absorption of SO2 with ethylenediamine/phosphoric acid and ethylenediamine/boric acid were conducted in packed column. The desulfurization efficiency can reach 97% under pH value of the absorbents 6.0～7.0, and liquid-gas ratio 0.82 L·m-3. Ethylenediamine/boric acid solution was more suitable for a wide range of SO2 concentration and gas flow rate. The packing absorption column was designed to deal with 10000 Nm3·h-1 simulated flue gas using ethylenediamine/boric acid solution.Thirdly, the method of series rate was used to study the impacts of the initial concentration of ethylenediamine([Cen]), air flow rate([Q]), pH value of the absorbents and reaction temperature on antioxidant of the absorbents. The oxidation kinetic equations of ethylenediamine/phosphoric acid solution and ethylenediamine/boric acid solution were given rp=1.455exp(-2.074×104/RT)[Cen]0.6089[Q]0.9216[pH]-8.0490,rB=0.1083exp-1.207×104[Cen]0.2826[Q]0.9972[pH]-4.9894, respectively. The activation energy of the Ethylenediamine/boric acid solution was 12.70 kJ/mol, and points that ethylenediamine/boric acid solution was oxidized easily.Finally, water-bath microwave method was used for twelve hydroxyl ammonium ionic liquids (ILs) synthesis. Taking ethanolamine lactate ILs as an example, the results showed that reaction time reduces from 20 h to 0.5 h, and the yield increases from 77.5% to 92.7% with water-bath microwave, compared with traditional room temperature synthesis method. The results of orthogonal experiment (L9(34)) showed that optimal preparation conditions were under 65℃, wave power of 300 W for 30 min with the molar ratio 1:1.1 (ethanolamine vs. lactic acid). At the equilibrium, the solubility of SO2 in ethanolamine lactate ILs was 0.51 (mole fraction), higher than others. Etyhanolamine lactate ILs was a better absorbent for SO2. The optimal temperature for the absorption and desorption process were 25℃and 90℃, respectively. The optimal desorption time was 60 min. It was also found that water-bath microwave temperature programming method can improve the release of the absorbed SO2 from ILs. After five cycles, the recovery of SO2 was 84%, and ILs has good reproducibility. The FT-IR and 1HNMR spectra of the SO2-free ILs and the SO2-absorbed ILs were determined. SO2 reacts with NH2 group on the cation, while O atom on S=O probably froms intramolecular hydrogen bond with H atom of the amine. SO2 was removed from the simulated flue gas.
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