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In recent years, metal-organic framework derivatives have been regarded as materials with great potential for water treatment applications. In this study, we employed a polyvinylpyrrolidone (PVP)-assisted copper-cobalt bimetallic zeolitic imidazole framework (ZIF) as a template to rationally design nanosheet-like mixed metal oxide embedded nitrogen-doped carbon (CuCoO-PC). CuCoO-PC exhibited excellent degradation potential towards metronidazole (MNZ) and achieved almost complete degradation within 7 min through the activation of peroxymonosulfate (PMS). Importantly, the introduction of copper into CuCoO-PC established strong interactions between copper and cobalt, accelerating the activation performance of PMS. Furthermore, PVP, rich in nitrogen atoms, formed strong coordination interactions with ZIF precursors, which effectively protected the morphological stability of ZIF at high temperature, preventing collapse and aggregation. Meanwhile, the formation of nitrogen-doped carbon networks provides a pathway for the generation of non-radical. The study found that CuCoO-PC continuously activated PMS, generating various reactive oxygen species (ROS), among which SO 4 •- and 1O 2 played decisive roles. By calculating the HOMO, LUMO, and Fukui functions, we identified the reactive sites of MNZ and proposed possible degradation pathways. CuCoO-PC demonstrated excellent catalytic performance, reduced toxicity of intermediate products, and good reusability, all of which highlight its enormous potential in practical applications. [Display omitted] • CuCoO-PC composites are prepared using PVP to enrich the nitrogen content. • CuCoO-PC/PMS system exhibits prominent catalytic performance for MNZ removal. • SO 4 •- and 1O 2 was the main active substance involved in the MNZ degradation. • CuCoO-PC was stable and effective in multiple cycles of MNZ degradation efficiency. • The most reactive site on MNZ molecule was predicted by DFT calculation. [ABSTRACT FROM AUTHOR]

Highly efficient multifunctional adsorbent successfully realizes the removal of Cr ions from wastewater. The adsorbent is easily separated from the water to avoid secondary pollution. [Display omitted] • A novel 3D multifunctional composite magnetic adsorbent material has been successfully synthesized and applied for the removal of Cr(VI) from solution. • The composite adsorbent enables efficient capture and reduction of Cr(VI) under full light exclusion conditions. • The exceptional recyclability mitigates the issue of secondary contamination from the adsorbent. Designing a magnetic adsorbent material that is both reducible and has strong adsorption properties is significant in reducing Cr(VI) ion pollution. Herein, a 3D multifunctional composite adsorbent for Cr(VI) ions was obtained by using Fe 3 O 4 surface-arrayed magnesium iron layered double hydroxides (Mg/Fe-LDH) micro sheets as a substrate with in situ growth of Cu 2 O nanoparticles (Cu 2 O NPs) on their surfaces. Under dark conditions, adsorption capacity of the Cu 2 O@LDH@Fe 3 O 4 for Cr(VI) was up to 218.82 mg·g−1, surpassing that of Cu 2 O, Mg/Fe-LDH@Fe 3 O 4 , and Mg/Fe-LDH by factors of 1.39, 4.41, and 8.32 respectively. Surprisingly, the removal of Cr(VI) was as high as 76.16 % by the Cu 2 O@LDH@Fe 3 O 4 (C initial = 200 mg/L, pH = 3). Kinetic, isotherm, and thermodynamic results reveal that the removal of Cr(VI) by the Cu 2 O@LDH@Fe 3 O 4 is consistent with the pseudo-second-order kinetic model of spontaneous monomolecular layer chemisorption. Density functional theory (DFT) calculations show that HCrO 4 - has a lower energy band gap and is more easily reduced by Cu 2 O. Therefore, the reason for the adsorbent having more removal effect under acidic conditions was revealed. The XPS and FT-IR experimental mechanism analysis results indicated that Cr(VI) is immobilized on the Cu 2 O@LDH@Fe 3 O 4 surface through electrostatic interactions, followed by reduction to Cr(III) by Cu 2 O NPs, which is subsequently adsorbed on the surface of the Cu 2 O@LDH@Fe 3 O 4. This novel adsorbent structure and unique Cr(VI) removal mechanism provide new ideas for the design of future adsorbents. [ABSTRACT FROM AUTHOR]