Efficient uptake of NH3 by dual active sites NH4SCN-imidazole deep eutectic solvents with low viscosity

Development of high-efficient solvents for NH 3 capture to improve the quality of atmosphere and ecological environment is a hot research topic. Deep eutectic solvents (DESs) as NH 3 absorbents can overcome some problems troubling the traditional NH 3 capture process. In this work, NH 4 SCN was paired with imidazole (Im) DESs to form low viscous DESs with dual active sites for highly efficient NH 3 absorption. The effects of absorption temperature, gas flow rate, water content, molar ratio on NH 3 absorption performance as well as physical properties of NH 4 SCN/Im DESs were systematically investigated. The results show that NH 4 SCN/Im DESs can rapidly capture NH 3 with good recycling performance, while the gas flow rate only shortens the absorption time. The NH 3 absorption capacity of NH 4 SCN/Im DESs decreased with increasing temperature and NH 4 SCN/Im molar ratio. The absorption capacity of NH 4 SCN/Im (1:2) DES reaches 9.65 mol NH 3 /kg DESs for atmospheric NH 3 . Based on 1 H NMR and IR spectroscopy analysis, the strong hydrogen bond between protic ammonium cation and NH 3 plays the major essence of efficient NH 3 capture for NH 4 SCN/Im DESs.