Highly Efficient Absorption of NO by Dual Functional Ionic Liquids with Low Viscosity

In this work, we demonstrate an innovative strategy for efficient and sustainable absorption of NO in a series of ionic liquids (ILs) containing amine groups and azole groups. The results show that the ILs have low viscosities and high performance for NO absorption. For instance, [TEPA][Im] had a high absorption capacity of 6.79 mol NO per mol IL at 30 °C and ambient pressure. The absorbed NO was easily released by heat treatment, and the regenerated IL had significant reversibility. The results of 1H NMR, UV spectra, and FT-IR spectra of ILs before and after NO absorption indicated that the absorption of NO in the [TEPA][Im] mainly resulted from a chemical interaction. NO interacts with not only the secondary amine groups in the cation but also N-imidazole in the anion through the formation of NONOate, indicating [TEPA][Im] is a dual functional IL. By introducing this efficient and reversible absorption of NO by ILs, our work broadens the method of NO capture.