absorption of so2 in aqueous solutions of mixed hydroxylammonium dicarboxylate ionic liquids

three new hydroxylammonium dicarboxylate ionic liquids (ils) dimethylethanolammonium dimalonate ([dmeah][dimalonate]), dimethylethanolammonium dimalate ([dmeah][dimalate]) and dimethylethanolammonium diglutarate ([dmeah][diglutarate]) were synthesized and mixed with free dmea and water to form novel hybrid solvents for so₂ absorption. the mixed absorbents exhibited low viscosity in the range of 6–13 mpa s at 313.2 k, favoring the transfer performance of so₂ absorption. significantly, they reached so₂ absorption equilibrium in less than 50 s, and their absorption capacities were as high as 0.1–0.6 mol so₂ per mol il at 313.2 k and 0.004 bar so₂ partial pressure. so2 solubility increased with increasing dmea/il molar ratio, whereas desorption efficiency decreased. ph significantly affected so₂ absorption and desorption performance in the mixed absorbents. the optimal ph for desulfurization was approximately 4.5–5.5, a compromise between absorption and desorption ability. compared with pure task-specific ils for so₂ absorption, which are too expensive and viscous for flue gas desulfurization, the mixed absorbents described in this study have more practical applications.