Sulfate ionic liquids impregnated 2D boron nitride nanosheets for trace SO2 capture with high capacity and selectivity

Owing to the abundant ionic sites and good molecular recognition ability of ionic liquids (ILs), the impregnation of ILs on support materials is an attractive strategy for trace SO2 capture with both desired capacity and high selectivity. Herein, we successfully prepared a kind of hexagonal boron nitride (h-BN) nanosheets impregnated sulfate functionalized ILs tetramethylethylenediamine ethylsulfate (x[TMEDA][DES]@BN, x = mass ratio) for capture of low-concentration SO2. It is found that the low-concentration SO2 uptakes of 1.5[TMEDA][DES]@BN were extremely high, with the amount of 2.3 mmol g-1 at 293.2 K and 0.01 bar, and 0.82 mmol g-1 at 293.2 K and 0.002 bar. Meanwhile, 1.5[TMEDA][DES]@BN showed a very fast SO2 adsorption rate and reached an unprecedented SO2/CO2 selectivity (2714) for the mixture of 1% SO2 and 99% CO2. Finally, dynamic column breakthrough tests further confirmed the excellent separation performance and good reversibility of 1.5[TMEDA] [DES]@BN in deeply removing 2000 ppm SO2 in the mixture of SO2/CO2/N-2.