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.

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The relationship between the interfacial rheology of nanoparticle (NP) laden air-brine interfaces and NP adsorption and interparticle interactions is not well understood, particularly as a function of the surface chemistry and salinity. Herein, a nonionic ether diol on the surface of silica NPs provides steric stabilization in bulk brine and at the air-brine interface, whereas a second smaller underlying hydrophobic ligand raises the hydrophobicity to promote NP adsorption. The level of NPs adsorption at steady state is sufficient to produce an interface with a relatively strong elastic dilational modulus E′ = dγ/d ln A. However, the interface is ductile with a relatively slow change in E′ as the interfacial area is varied over a wide range during compression and expansion. In contrast, for silica NPs stabilized with only a single hydrophobic ligand, the interfaces are often more fragile and may fracture with small changes in area. The presence of concentrated divalent cations improves E′ and ductility by screening electrostatic dipolar repulsion and strengthening the attractive forces between nanoparticles. The ability to tune the interfacial rheology with NP surface chemistry is of great interest for designing more stable gas/brine foams.

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