Issue 45, 2021

Investigation of NH3 absorption by protic imidazolium thiocyanate-based deep eutectic solvents with multiple binding sites and low viscosity

Abstract

Ammonia (NH3) is not only an important basic chemical raw material but also a typical polluting gas. The separation and recovery of NH3 from tail gas is of great significance for human health and the environment. In this study, a series of protic ionic liquid-based deep eutectic solvents (PIL-based DESs) were constructed by pairing imidazolium thiocyanate ([Im][SCN]) as the hydrogen-bond acceptor (HBA) with various hydrogen-bond donors (HBDs) [glycerol (Gly), ethylene glycol (EG), formamide (FM), acetamide (AT), and caprolactam (CL)]. Their physical properties and NH3 absorption performance were systematically investigated. The results showed that [Im][SCN] played a role in chemical NH3 absorption in the PIL-based DESs, while the HBDs mainly contributed to physical NH3 capture. HBDs containing hydroxyl groups demonstrated an evident improvement in NH3 absorption capacity compared to those with amide groups. [Im][SCN]–EG (1 : 3) demonstrated the highest mass capacity of 0.233 g NH3/g DES, which exceeded those of all the other IL-based DESs and originated from the multiple interactions between the acidic H as well as the hydroxyl groups in the DES and NH3, according to the 1H NMR and FTIR spectral analysis. Furthermore, [Im][SCN]–EG (1 : 3) indicated a high NH3/CO2 selectivity of 632.2, satisfactory thermal stability and excellent recyclability. [Im][SCN]–EG DESs possess great potential as attractive absorbents in NH3 separation and recovery.

Graphical abstract: Investigation of NH3 absorption by protic imidazolium thiocyanate-based deep eutectic solvents with multiple binding sites and low viscosity

Article information

Article type
Paper
Submitted
08 Aug 2021
Accepted
20 Oct 2021
First published
20 Oct 2021

New J. Chem., 2021,45, 21108-21115

Investigation of NH3 absorption by protic imidazolium thiocyanate-based deep eutectic solvents with multiple binding sites and low viscosity

Z. Zhou, K. Li, K. Zong, X. Deng and D. Deng, New J. Chem., 2021, 45, 21108 DOI: 10.1039/D1NJ03816H

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