Highly efficient and reversible adsorption of ammonia by incorporation of deep eutectic solvents into silica gel and Al2O3

Abstract

The uptake of NH₃ in the industrial tail gas will improve the environmental quality for human health and ecology. Adsorption separation has the advantages of simple operation and low energy consumption. However, the relatively low adsorption capacity severely hinders its practical utilization. In this work, four glycerol-based deep eutectic solvents (DESs) were incorporated into porous silica gels (SGs) and Al₂O₃ with a large surface area and pore structure to form novel DES/SG and DES/Al₂O₃ composites. The obtained materials were systematically characterized by FTIR, SEM, BET, and TGA and further evaluated for NH₃ adsorption. The results showed that the acidic GuSCN:Gly DES played an indispensable role for the high adsorption ability of the composite. 40 wt% GuSCN : Gly (1 : 3) DES/SG can capture 115.40 mg NH₃ per gram adsorbent, which is better than most of the solid adsorption materials reported in the literature and even 30% higher than the original SG. The high adsorption capacity, outstanding thermal stability, and good reusability confirm the success of the present strategy. This study will provide a useful idea for designing DES-supported composites for NH₃ separation applications.