Highly efficient absorption of NO by amine-based functional deep eutectic solvents

To explore new reversible and environmentally friendly solvents for the capture of nitrogen monoxide (NO), a series of amine-based functional deep eutectic solvents (DESs) were designed by ammonium salts (triethylenetetramine chloride-[TETA]Cl, and tetraethylenepentamine chloride-[TEPA]Cl) and polyhydric alcohols (ethylene glycol-EG, 1,3-propanediol-PG, glycerol-Gy and polyethylene glycol 2000-PEG). All the DESs prepared showed good absorption capacities for 10 v% NO. EG-[TEPA]Cl DES (n EG/n [TEPA]Cl = 3:1) had the highest absorption capacity of 10 v% NO, 0.327 g NO per g DES at 30 oC. Moreover, the EG-[TEPA]Cl DES (n EG/n [TEPA]Cl = 3:1) showed excellent reusability for at least 5 recycles. The comparison of FT-IR and UV-vis spectra of DESs before and after NO absorption was made to study the absorption mechanism. The results indicated that the absorption of NO by the DESs was mainly a chemical process. One mole of amine group in HBA could react with two moles of NO to produce R1R2N-(NO)-NO, where both R...