Azolide-based deep eutectic solvents exhibit a high CO2 absorption capacity by forming carbonate species.

In this work, the anion-functionalized deep eutectic solvents (DESs) comprising solid organic salt tetraethylammonium tetrazolate ([N2222]­[Tetz]) and ethylene glycol (EG) at a molar ratio 1:2 were synthesized to capture SO2. DESs [N2222]­[Tetz]-EG­(1:2) could capture 0.853 g of SO2/g solvent (4.31 mol SO2/mol solvent) at 1.0 atm and 20 °C. Interestingly, [N2222]­[Tetz]-EG­(1:2) exhibited a high SO2 absorption capacity of 0.140 g of SO2/g solvent (0.708 mol SO2/mol solvent) at 2000 ppm, which was much higher than the absorption capacity (0.002 g of SO2/g solvent or 0.009 mol SO2/mol solvent) of non-functionalized DESs consisting of tetraethylammonium chloride ([N2222]­[Cl])-EG­(1:2) under the same conditions. Moreover, [N2222]­[Tetz]-EG­(1:2) can be reused and showed good reversibility. Nuclear magnetic resonance and Fourier transform infrared results indicated that the high SO2 absorption capacity of [N2222]­[Tetz]-EG­(1:2) was due to the chemical reaction between SO2 and anion [Tetz]−, and the SO2 absorption enthalpy of [N2222]­[Tetz]-EG­(1:2) was −52.7 kJ/mol which also confirmed the strong interaction between SO2 and [N2222]­[Tetz]-EG­(1:2).

The SO 2 absorption capacities of two ionic liquid mixtures formed by 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) and 1-ethyl-3-methylimidazolium thiocyanate ([Emim][SCN]) were studied. The ionic liquid mixtures with different molar ratios of [Emim][Cl] and [Emim][SCN] (1:1 and 1:2) can be easily synthesized. The SO 2 solubility in the two mixtures was investigated under different conditions. The results demonstrated that these mixtures were efficient for SO 2 absorption. [Emim][Cl]−[Emim][SCN](1:1) captured 0.50 g/g solvent at 20 °C and 0.10 atm. Under the low SO 2 partial pressure (1960 ppm), the [Emim][Cl]−[Emim][SCN](1:1) could capture 0.11 g/g solvent. The high SO 2 absorption capacity is mainly due to the strong charge-transfer interaction of the sulfur atom of SO 2 with the anions ([Cl] − and [SCN] − ). Moreover, the solvent [Emim][Cl]−[Emim][SCN](1:1) can be reused.

No abstract

An analytical method was developed for the simultaneous determination of thiocyanate and iodide by reversed‐phase liquid chromatography with UV detection using imidazolium ionic liquids as mobile phase additives. The chromatographic behaviors of the two anions on a C18 column were studied and compared with four types of reagents including imidazolium ionic liquids, pyridinium ionic liquids, 4‐aminophenol hydrochloride and tetrabutylammonium as mobile phase additives. The effects of the concentrations of imidazolium ionic liquids, organic solvents and detection wavelength on separation and detection of the anions were investigated. The role of ionic liquids, retention rules and mechanisms were discussed. The separation of the anions was performed on the C18 reserved‐phase column using acetonitrile‐0.3 mmol/L 1‐amyl‐3‐methylimidazolium tetrafluoroborate (10:90, v/v) as mobile phase, with column temperature of 35°C, flow rate of 1 mL/min and detection wavelength of 210 nm. Under these conditions, the two anions can be completely separated within 6 min. The limits of detection were 0.05 mg/L. The method was applied for the determination of thiocyanate and iodide in ionic liquid samples and iodide drugs, and the spiked recoveries ranged from 97 to 101%. The method is simple, accurate and meets the requirements of quantitative analysis for thiocyanate and iodide.