Efficient SO2 Capture by 2-(Diethylamino)ethanol/Hexadecane Phase Separation Absorbent

Removal of sulfur dioxide (SO2) from flue gas by developing a highly efficient phase-change absorption solution is an effective way to tackle increasingly serious air pollution problems. In this study, the phase-change absorption behaviors of SO2 by using low cost 2-(diethylamino)ethanol (DEEA)/hexadecane as absorbent/solvent was systematically studied. The homogeneous solution could be facilely and quickly changed into two immiscible liquid phases upon introducing low partial pressure SO2. The liquid–liquid phase-change phenomenon was attributed to the formation of zwitterionic product by the reaction of DEEA with SO2, which was insoluble in low polarity hexadecane. Specifically, the absorption capacity of DEEA toward SO2 under 20 °C could reach 0.51 and 1.56 g of SO2/g of DEEA at 0.02 and 1 atm, respectively, which exhibited front-rank absorption capacity to most reported works. In addition, it was suggested that the present absorbent exhibited a highly selective absorption property and high removal efficiency of SO2. The well-matched absorbent/solvent phase-change system holds a promising application in the treatment of industrial flue gases.