Debye Radius-Guided Mercury Sequestration via Nanoconfinement by Adaptive Nano-Ion Channels

Abstract

Rapid and targeted intervention during sudden mercury pollution incidents can significantly mitigate the harmful effects of mercury dissemination. Mesoporous metal–organic frameworks (MOFs) are demonstrated great promise for mercury wastewater purification, owing to their exceptional adsorption capacity. However, these materials often underperform at exceptionally high or low Hg(II) concentrations, limiting their use in emergencies. To address this issue, this study leverages nanostructure engineering techniques and, for the first time, fine-tunes the proportion of surfactants to construct a thiol-functionalized UiO-66 MOF (Nic-UiO-66-SH) with size-adjustable nano-ion channels for rapid Hg(II) pollution management in emergency contexts. The Nic-UiO-66-SH, with a maximum adsorption capacity of 1695.87 mg g⁻¹, can quickly and effectively adsorb Hg(II) at extreme concentrations (10–600 mg L⁻¹) within 2.5–105 min, bringing the concentration down to drinking water standards (<0.002 mg L⁻¹). This superior performance is attributed to the concentration-specific adsorption mechanism of ions in adaptive nano-ion channels based on Debye radius theory, which guides the precise control of channel size. Molecular simulations further validate the significant role of ion channels in optimizing Hg(II) diffusion and adsorption. This work establishes a theoretical foundation for the development of emergency wastewater purification materials and promotes their practical application in pollution response scenarios.