Beyond Adsorption: Synergistic Interfacial Dynamics and Nanoconfinement in UiO-66(Zr) Enhance Cu(II)–Carboxyl Complex Elimination via Sustainable Ligand Capture and Metal Recovery
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Date
2026
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Abstract
The removal of heavy-metal complexes (HMCs) from industrial wastewater remains challenging due to their stability and resistance to conventional methods. Here we reveal the critical yet overlooked roles of the adsorbent/adsorbate interfacial dynamics and nanoconfinement effects in governing HMC removal. Using UiO-66(Zr), a zirconium-based metal–organic framework (MOF), we demonstrate that interfacial proton transfer induces rapid acidification, decomplexing Cu(II)–carboxyl species into free copper ions and ligands. Nanoconfinement within UiO-66(Zr) octahedral cavities promotes ligand deprotonation and selective adsorption, while further released copper ions are precipitated via alkali treatment. This synergy achieves over 99.95% Cu removal, surpassing standalone methods. Fixed-bed column experiments validated its practicality, producing 1828 bed volumes of compliant water (<0.3 mg Cu/L) and enabling Cu recovery, outperforming individual components by 6–208-fold. Density functional theory calculations confirm stronger MOF interactions with deprotonated ligands than complexes, driven by electrostatic and Lewis acid–base interactions. This work highlights the mechanistic understanding of HMC removal by bridging dynamic interfacial processes and nanoconfinement-driven reaction pathways, offering a cost-effective, scalable solution for metal recovery as well.
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Heavy-metal complexes, Interfacial dynamics, Nanoconfinement, Metal−organic frameworks, UiO-66(Zr), Wastewater treatment