Investigation of Highly Efficient and Reversible Absorption of SO₂ Using Ternary Functional Deep Eutectic Solvents

Abstract

The efficient and reversible capture of lowconcentration SO 2 in flue gas has attracted increasing attention. In this work, a series of novel ternary functional deep eutectic solvents (DESs) based on 1-butyl-3-methylimidazolium chloride (BmimCl) as a hydrogen bond acceptor and ethylene urea (EU) along with azole derivatives as hydrogen bond donors were prepared to investigate the low-concentration SO 2 absorption. Results demonstrated that the studied ternary DESs exhibited superior SO 2 capture performance at low concentration. Of note, EU/4-methylimidazole (4-CH 3 -Im)/BmimCl (1:2:1) and EU/4-CH 3 -Im/BmimCl (1:1:1) exhibited high SO 2 available absorption capacity (0.259 and 0.209 g SO 2 /g DES at 0.2 vol % SO 2 and 20 °C) and satisfactory desorption efficiency. Furthermore, the ternary DESs showed high thermostability, outstanding reusability, and reversibility during the five-cycle absorption−desorption experiments. Moreover, combining spectroscopic investigations with quantum chemical calculations, it can be concluded that 4-CH 3 -Im in DESs chemically interacted with SO 2 to effectively capture SO 2 , and EU could tune the reactivity of the active site in 4-CH 3 -Im to improve the desorption capability of DESs. Overall, these ternary DESs with distinguished desulfurization performance (high SO 2 available absorption capacity and improved desorption capability) have promising prospects in flue gas desulfurization.

Homologue-paired liquids as special non-ionic deep eutectic solvents for efficient absorption of SO2

“…11 So far, various DESs have been examined for SO 2 capture, such as choline-based DESs, 12 betaine-based DESs, 13 imidazolium-based DESs, 14 and azole-based DESs. 11 a ,15 However, due to the disadvantages such as high viscosity and corruption caused by halogen anions, DESs are still lacking practical applications.…”

Capture of Acidic Gases from Flue Gas by Deep Eutectic Solvents

“…An interesting phenomenon accompanied by the absorption process is that the colorless solvent gradually turned to brown in CPL:Im DES (1:1), which was also observed by Liu et al [29]. Based on previous research, Tantai et al put forward a novel strategy to prepare ternary functionalized DESs capable of chemically binding ultralow concentration (2000 ppm) SO 2 in the flue gas, by mixing low-cost azole derivatives with ternary EU:BmimCl DESs [53]. By comparing the absorption capacity of ternary EU:4-CH 3 -Im:BmimCl DESs (1:1:1, 2:1:1, 1:2:1, and 1:1:2) with binary DESs, including EU:BmimCl DES (1:1), CH 3 -Im:BmimCl DES (1:1) and 4-CH 3 -Im:BmimCl DES (2:1), as shown in Table 2.…”

“…For functionalized DESs, the stronger interaction between DESs and gases would make regeneration harder. For instance, due to the strong interaction between NO and DESs, the desorption rates of NO in Tetz:P 4444 Cl DES (1:1) [ [53]. Deng et al [49] reported that the different desorption behaviors of ACC:Im DES (1:2) and ACC:Tri DES (1:1) were related to the basicity of DESs.…”

Fluorescent Ionic Liquid Membranes Based on Coumarin for the Real-Time and Visual Detection of Gaseous SO2

“…Fourier transform infrared (FT-IR) spectra were recorded using a Nicolet iN10 Fourier-transform spectrometer. 1 H and 13 C NMR spectra were performed on a Bruker 400M NMR spectrometer. The density was measured by a pycnometer.…”

“…Sulfur dioxide (SO 2 ), one of the chief pollutants in ambient air, is emitted largely from fossil fuel combustion and has caused environmental and health problems, such as acid rain, and damage of respiratory system. − When healthy humans are repeatedly exposed to low concentrations of SO 2 , they may develop laryngitis, chronic bronchitis, and terrible infections of the respiratory tract . According to reports, the limits of human exposure to SO 2 gas in the long-term and short-term are 2 and 5 ppm, respectively.…”