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Phenol-Based Ternary Deep Eutectic Solvents for Highly Efficient and Reversible Absorption of NH₃
- Zhong, Fu-Yu, Peng, Hai-Long, Tao, Duan-Jian, Wu, Ping-Keng, Fan, Jie-Ping, Huang, Kuan
- ACS sustainable chemistry & engineering 2019 v.7 no.3 pp. 3258-3266
- absorption, acidity, ammonia, choline, desorption, energy efficiency, enthalpy, ethylene glycol, gases, phenol, solvents, temperature, thermodynamic models
- 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 NH₃ capture. The effects of temperature, pressure, and DES composition on NH₃ capacities were investigated systematically. By utilizing the weak acidity of PhOH, highly efficient and reversible absorption of NH₃ was realized in PhOH-based ternary DESs. The absorption capacities of NH₃ 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 NH₃ could be easily stripped out at elevated temperature and reduced pressure, with negligible loss in NH₃ capacities after 10 adsorption–desorption cycles. The thermodynamic properties of the NH₃ 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 NH₃ 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 NH₃ from industrial gases.