Regenerative low‐cost ionic liquids: Synthesis, characterization, and application in desulphurization of flue gases

Abstract

AbstractThree ionic liquids (ILs) containing the same cation but different anions were synthesized and used to separate SO2 from its mixture with air in a semi‐batch bubble column absorber. Desulphurization efficiency was determined using a state‐of‐the‐art experimental set‐up relevant to chemical process industries concerning the important process variables. The virgin and exhausted ILs were characterized using TGA, FTIR, and 1H NMR analyses. The concentrations of SO2 at the inlet to and exit from the absorber were measured using a ZRJFAY36, Fuji, Japan infrared SO2 analyzer. A maximum of 92 percent removal efficiency (PRE) was achieved from a feed gas containing 250–1500 ppm SO2 with the use of 2‐hydroxyethyl ammonium lactate [MEA][L] or tri (2‐hydroxyethyl) ammonium lactate ([TEA][L]), as the absorbents. This could be further enhanced by the interactive effect of the simultaneous increase in the superficial velocity of the gas and the volume of IL fed into the absorber. However, PRE was about 20% less with tri (2‐hydroxyethyl) ammonium salicylate ([TEA][S]). It was observed that the ILs, [MEA][L] and [TEA][L], were fairly suitable for flue gas desulphurization in industrial situations. A design criterion for continuous operation using two semi‐batch absorbers has been proposed.