Efficient Absorption of Low Partial Pressure SO2 by 1-Ethyl-3-methylimidazolium Chloride plus N-Formylmorpholine Deep Eutectic Solvents

The removal of SO2 from flue gas attracted sustainable attention for the improvement of atmospheric quality and human healthy. In this work, 1-Ethyl-3-methylimidazolium chloride (EmimCl) was paired with N-formylmorpholine (NFM) to form deep eutectic solvents (DESs) as the media for SO2 absorption. The absorption performance of SO2 in EmimCl-NFM DESs with various molar ratios were experimentally measured. Results showed that all the DESs exhibited efficient and reversible absorption behavior for low concentration SO2, with SO2 absorption capacity as high as 0.220 g per g DES of EmimCl-NFM (1:1) at 293.15 K and SO2 partial pressure of 1.0 kPa, surpassing those of most absorbents/adsorbents previously reported. The DES could remain satisfactory absorption performance and thermal stability after consecutive five cycles. The viscosity, density, TGA, FTIR, and NMR spectroscopy were utilized to characterize the changes between fresh and SO2-loaded DESs systematically. Present DESs showed potential application in...