Investigation of NH3 absorption by protic imidazolium thiocyanate-based deep eutectic solvents with multiple binding sites and low viscosity. (2nd November 2021)

• Record Type: Journal Article
• Authors: Zhou, Ziyue; Li, Ke; Zong, Kai; Deng, Xiaoxia; Deng, Dongshun
• Is Part Of: New journal of chemistry. Volume 45:Number 45(2021)
• Page Start: 21108
• Page End: 21115
• Publication Date: 2021-11-02
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/d1nj03816h
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : Protic [Im][SCN]-based DESs with multiple binding sites and low viscosity for NH3 capture and separation are reported. 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 1 H 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.