Thiol-functionalized metal-organic framework@dendritic mesoporous silicon core-shell composite for efficient removal of Hg(II) in water

A novel core-shell MIP-203-SH@DMSN S -SH composite with excellent Hg(II) adsorption is synthesized. • A maximum of Hg(II) adsorption capacity of 517.0 mg/g is achieved within 2 min. • Hg-S/Hg-O chemisorption plus hierarchical pores enable ultra-fast kinetics. • pH adaptability, anti-interference ability and reusability support practical application. The safety of water is facing severe challenges due to heavy metal pollution. Mercury, which is highly toxic and bioaccumulative, has become a global threat. The development of advanced adsorbents with high capacity, good chemical stability, and efficient removal for Hg(II) removal remains a major challenge in water remediation. In this study, a novel core-shell composite with thiol-functionalized dendritic mesoporous silicon nanospheres (DMSN S -SH) as the core and zirconium-based metal-organic framework (MIP-203-SH) as the shell was synthesized by hydrothermal method. The optimized composite presents a unique walnut kernel-like structure with high specific area and hierarchical pore structure, which significantly improves the accessibility of active sites. The material exhibited excellent adsorption performance with a maximum adsorption capacity of 517.0 mg/g at 298 K. The dendritic mesoporous architecture of the support provided mass transfer channels, which led to remarkably fast adsorption kinetics and achieved removal rate of 90% within 2 min. The adsorption process fits well with the Sips isotherm pseudo-second-order kinetic model, indicating the existence of a monolayer chemisorption mechanism on the heterogeneous surface. X-ray photoelectron spectroscopy further confirmed that the adsorption mechanism was mainly driven by the strong coordination of Hg(II) with thiol and hydroxyl groups (forming Hg S and Hg O bonds), as well as electrostatic interactions. Furthermore, the adsorbent material exhibited excellent stability over a wide pH range (1–7), selectivity, and regeneration, maintaining high removal rate of 99.7% in actual industrial wastewater containing Hg(II). This study provides a new strategy for developing Hg(II) adsorption materials with fast, efficient and good adaptability, but also offers important theoretical basis and technical support for the Hg(II) treatment in wastewater. Download: Download high-res image (144KB) Download: Download full-size image