CO2 CAPTURE BY 1-BUTYL-3-METHYLIMIDAZOLIUM TETRAFLUOROBORATE-PROMOTED POTASSIUM CARBONATE SOLUTION IN HOLLOW FIBER MEMBRANE CONTACTORS

CO2 is one of the main greenhouse gases responsible for global warming and is also a major component of biogas. Capturing CO2 from biogas for CH4 purification has a great economic and environmental value. In this study, CO2-capture performance of a mixed aqueous solution of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) and potassium carbonate (K2CO3) was investigated in detail at 25 degrees C. To investigate the influence of solution composition on CO2 absorption flux, six mixtures of absorbents were prepared by varying the concentrations of [bmim]BF4 in the range from 0 M to 0.03 M. Moreover, four common amino acid salt absorbents, including potassium glycinate (PG), potassium sarcosine (PS), potassium L-leucine (PLL), and potassium L-serine (PLS), were selected and compared with the mixed ionic liquid (IL) aqueous solutions. The results obtained revealed that the presence of [bmim]BF4 at low concentrations in K2CO3 aqueous solution had a beneficial influence on CO2 absorption flux, and the best absorption performance of CO2 was obtained when the molar ratio of [bmim]BF4 to K2CO3 was 1:9. In addition, this mixed [bmim]BF4 + K2CO3 aqueous solution with a molar concentration of 1:9 showed better CO2 absorption performance than PG aqueous solution, which had the best CO2 absorption performance among the four amino acid salt solutions studied under the same conditions.