Phenol-Based Ternary Deep Eutectic Solvents for Highly Efficient and Reversible Absorption of NH₃

Abstract

In this work, a class of deep eutectic solvents (DESs) formulated by choline chloride (ChCl), phenol (PhOH), and ethylene glycol (EG) were designed and synthesized for NH 3 capture. The effects of temperature, pressure, and DES composition on NH 3 capacities were investigated systematically. By utilizing the weak acidity of PhOH, highly efficient and reversible absorption of NH 3 was realized in PhOH-based ternary DESs. The absorption capacities of NH 3 in prepared DESs can reach as high as 9.619 mol/kg (0.162 g/g) at 298.2 K and 101.3 kPa, ranking one of the best reported to date. The captured NH 3 could be easily stripped out at elevated temperature and reduced pressure, with negligible loss in NH 3 capacities after 10 adsorption−desorption cycles. The thermodynamic properties of the NH 3 absorption process, such as reaction equilibrium constants, Henry's constants, and absorption enthalpies, were also calculated with the assistance of thermodynamic modeling. It is found that the NH 3 absorption process exhibits a moderate enthalpy change of −36.91 kJ/mol, indicating the potentially energy-efficient feature of a subsequent desorption process. The results obtained herein suggest that PhOH-based ternary DESs are promising media for the capture of NH 3 from industrial gases.

Promising Technological and Industrial Applications of Deep Eutectic Systems

“…Akhmetshina et al reported a study on the gas sorbent properties of the DES 1-butyl-3-methyl imidazolium methanesulfonate/urea toward ammonia, hydrogen sulfide and carbon anhydride, with good results relative to the sorption capacity of the ammonia [98]. This study follows the results presented by Zhong [99,100] A different approach to the development of suitable DESs-based systems for trapping VOCs was reported by Di Pietro and co-workers [103]. The Authors demonstrated the possibility to change the ability of cyclodextrin to encapsulate toluene and aniline by performing the process in DES (choline chloride/urea 1:2).…”

Dual‐functionalized protic ionic liquids for efficient absorption of NH3 through synergistically physicochemical interaction

“…In order to evaluate the potential of DPILs for industrial applications of NH 3 absorption, the ILs and deep eutectic solvents (DESs) reported to absorb NH 3 were compared with this work, as shown in Table . The results indicated that the NH 3 solubility in [EtOHim][NTf 2 ] is over 30‐fold greater than that of [Emim][NTf 2 ], and four‐fold greater than that of the functionalized IL [EtOHmim][NTf 2 ], which is superior to any nonmetallic ILs reported so far.…”

Do Cyclodextrins Encapsulate Volatiles in Deep Eutectic Systems?

“…2,3,5,6,[10][11][12][13][14] Deep Eutectic Systems (DES) have been recently suggested as innovative materials with potential in gas absorption. [15][16][17][18] Practically speaking, a DES is the result of the combination in the proper ratio of an opportune hydrogen-bond donor (HBD) and a hydrogen-bond acceptor (HBA). [19][20][21] Self-association of the HBD and HBA lowers the entropic difference of the phase transition, so that basically a eutectic is formed with a depressed freezing point that lies well below that of the individual components.…”