Efficient adsorption and desorption of elemental mercury by ordered mesoporous cerium oxide nanoparticles derived from Ce-based metal–organic frameworks

• Published in: Separation and purification technology Vol. 354; p. 129139
• Main Authors: Li, Bohao, Zhou, Jinsong, Liu, Haoyun, Zhou, Lingtao, Liu, Zhuang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 19.02.2025
• Subjects: Density functional theory; Hg0 adsorption; Ordered mesopores MOFs; Wet desorption; Hg0 adsorption; Density functional theory; Wet desorption; Ordered mesopores MOFs
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.129139

[Display omitted] •A novel Hg0 adsorbent OM-CeO2 with ordered mesoporous shells was synthesized.•OM-CeO2 inherits the structure of mesoporous MOF and possesses better reactivity.•Structural advantage facilitates mass transfer in adsorption and desorption.•Wet desorption of Hg compounds synchronizes the restoration of active substances.•Transformation reactions of Hg on pyrolyzed OM-CeO2 have lower energy barriers. Metal oxide-based adsorbents not only exhibit effective elemental mercury (Hg0) removal capacity but also offer suitability for wet desorption, which is a green treatment method to avoid secondary contamination of deactivated adsorbents. Nevertheless, the limited dispersing capacity of the carrier restricts the loading of active substances, hindering further enhancement of adsorption capacity. The pore structure of adsorbent is also a key factor for wet desorption. In this work, we synthesized a hollow cerium-based metal–organic framework (Ce-mesoMOF) as a sacrificial precursor to obtain ordered mesoporous cerium oxide (OM-CeO₂) via a mesoporous genetic pyrolysis-oxidation mechanism. OM-CeO2 inherits the excellent structural properties of mesoporous MOF with better catalytic activity, exhibiting strong adsorption capacity in various atmospheres (97.6 % in pure N2, 98.8 % in N2 + H2S). Wet desorption of Hg compounds and reduction of the active site can be synergized in Na2S2O3 solution. The octahedral structure with an ordered mesoporous shell greatly facilitates the mass transfer process, as evidenced by the strong adsorption capacity and fast kinetic parameters of OM-CeO2. Density functional theory analysis reveals that the conversion reaction of adsorbed Hg has a low energy barrier on the pyrolytic-oxidized OM-CeO2 and the inhibitory effect of reactive S for Hg0 adsorption transforms into a facilitating effect. This study leverages the structural advantages of ordered mesoporous MOFs in the field of Hg adsorption and imparts reactivity through modification for efficient adsorption–desorption.