Silica-Supported Ionic Liquid For Efficient Gaseous Arsenic Oxide Removal Through Hydrogen Bonding

The emission of highly toxic As2O3 (g) from nonferrous metal smelting has been exacerbating environmental concerns. In this study, we prepared a novel adsorbent (SMIL-X) by loading ionic liquid (IL) ([HOEtMI]NTf2) into MCM-41 through an impregnation–evaporation process and applied to the adsorption As2O3 (g). SMIL-20% exhibited an adsorption capacity of 35.48 mg/g for As2O3 (g) at 400°C, approximately 490% higher than that of neat MCM-41. The characterization of SMIL-X indicated that IL was mainly supported on MCM-41 through the O–H…O bond formed between the hydroxyl group (–OH) of IL and the silanol group (Si–OH) of MCM-41 and the O–H…F formed between the C–F of IL and Si–OH of MCM-41. Notably, hydrogen bonds significantly contributed to the adsorption of As2O3 (g), with –NH and –OH groups on the adsorbent forming hydrogen bonding with As–O species (i.e., N–H…O and O–H...O), and proved to be superior to traditional adsorbents relying on van der Waals forces. Moreover, after exposure to high concentrations of SO2, the adsorption capacities were maintained at 76% of the initial adsorption efficacy, demonstrating a certain level of sulfur resistance. This study presented a novel adsorbent for purification of As2O3 (g) and showed its practical application potential in the flue gas.