Efficient and Reversible Nitric Oxide Absorption by Low-Viscosity, Azole-Derived Deep Eutectic Solvents

Deep eutectic solvents (DESs) have been extensively studied and applied to the absorption of acid gases. However, the absorption of nitric oxide (NO) by DES has rarely been reported. In this work, we found that NO can be absorbed by azole-derived DESs effectively and reversibly. A series of DESs with low viscosity based on tetrazolium (Tetz), triazole, and imidazole as hydrogen bond donors (HBDs) and common ionic liquids as hydrogen bond acceptors (HBAs) were prepared. The absorption results showed that DESs based on tetrabutylphosphine chloride (P4444Cl) as HBA or Tetz as HBD exhibited higher NO absorption. Notably, Tetz/P4444Cl DES exhibited the NO absorption values of 2.10 and 1.01 mol/mol at 101.3 and 12 kPa partial pressures, respectively, and 303.15 K. In addition, the NO absorption capacity decreased continuously with the increasing temperature. The evaporation of Tetz/P4444Cl DES can be ignored during the absorption progress. The results of thermogravimetric analysis measurement and regeneration e...