One-pot solvothermal synthesis of Cu-Fe-MOF for efficiently activating peroxymonosulfate to degrade organic pollutants in water:Effect of electron shuttle

Functional group modulation of Fe-1,3,5-benzenetricarboxylic acid materials: Enhancing peroxymonosulfate activation while preserving synthetic simplicity

This work aims to design peroxymonosulfate (PMS) catalytic materials that exhibit both high catalytic activity and ease of preparation. Fe-1,3,5-benzenetricarboxylic acid (Fe-BTC), known for its environmentally friendly and convenient synthesis, was selected as the template. A series of derived materials were developed under green and mild conditions using a functional group modulation strategy, in which one -COOH group in BTC was substituted with -NO2, -NH2, pyridine nitrogen, or -H. Among these, the amino-modified Fe-BTC (Fe-IPA-NH2), derived via -NH2 substitution, demonstrated a significant improvement in catalytic performance compared to Fe-BTC. Fe-IPA-NH2 effectively activated PMS to degrade 99 % of metronidazole (MNZ) within 60 min. Through comprehensive characterization of the physicochemical properties of the synthesized materials, the influence of functional group modulation on the catalyst's structure-activity relationship was elucidated. The substitution of -COOH with -NH2 enhanced PMS activation by promoting both mass transfer and electron transfer processes. Liquid chromatography-mass spectrometry (LC-MS) analysis revealed the degradation pathways of MNZ, which included hydroxyethyl cleavage, methyl oxidation, N-denitration, and ring-opening reactions. Toxicity assessment indicated that the Fe-IPA-NH2/PMS system holds promise for MNZ detoxification. Electron paramagnetic resonance spectroscopy and quenching experiments identified singlet oxygen (1O2) as the dominant reactive species in the Fe-IPA-NH2/PMS system, and a possible catalytic mechanism was proposed. Additionally, Fe-IPA-NH2 retained the key advantage of Fe-BTC-its facile and eco-friendly synthesis. When Fe-IPA-NH2 was incorporated into a ceramic membrane via an in situ assembly process, the resulting membrane catalytic reactor exhibited effective performance in water treatment. This study offers a compelling strategy for the development of iron-based metal-organic complexes that integrate eco-friendly synthesis, enhanced PMS catalytic activity, and versatile application potential.

Advancements in MOF-based resistive gas sensors: synthesis methods and applications for toxic gas detection

Gas sensors are essential tools for safeguarding public health and safety because they allow the detection of hazardous gases. To advance gas-sensing technologies, novel sensing materials with distinct properties are needed. Metal-organic frameworks (MOFs) hold great potential because of their extensive surface areas, high porosity, unique chemical properties, and capabilities for preconcentration and molecular sieving. These attributes make MOFs highly suitable for designing and creating innovative resistive gas sensors. This review article examines resistive gas sensors made from pristine, doped, decorated, and composite MOFs. The first part of the review focuses on the synthesis strategies of MOFs, while the second part discusses MOF-based resistive gas sensors that operate based on changes in resistance.

Optimized Congo Red Dye Adsorption Using ZnCuCr-Based MOF for Sustainable Wastewater Treatment

This study presents the synthesis of a novel trimetallic ZnCuCr-TpIm metal-organic framework (MOF) via a solvothermal method, yielding cubic crystals of 300-500 nm. The integration of Zn, Cu, and Cr metal centers enhances the MOF's adsorption efficiency and structural stability, distinguishing it from conventional MOFs. The material achieves a high Congo red dye removal efficiency (96.5%) under optimal conditions: 40 mg adsorbent dosage, 55 °C, pH 6-7, and a 60 min contact time. Kinetic analysis reveals that the adsorption follows a pseudo-second-order model (R2 > 0.999), indicating chemisorption as the rate-limiting step, while equilibrium data align with the Langmuir isotherm model (R2 = 0.998), confirming a maximum adsorption capacity of 325 mg/g. FTIR and XRD analyses confirm strong interactions between the dye molecules and the MOF framework while preserving its crystalline structure. The ZnCuCr-TpIm MOF demonstrated exceptional stability, retaining 95% of its surface area after 72 h and maintaining over 90% adsorption efficiency after five reuse cycles, with minimal metal ion leaching (<1.2 ppm). The material also exhibited high resilience under varying pH, salinity, and simulated wastewater conditions, underscoring its potential for long-term and sustainable dye removal applications. These findings highlight the synergistic advantages of the trimetallic MOF, making it a promising candidate for efficient and stable wastewater treatment.

Highly Efficient Activation of Peroxymonosulphate by Co and Cu Co-Doped Sawdust Biochar for Ultra-Fast Removal of Bisphenol A

The rapid, efficient, and thorough degradation of Bisphenol A (BPA) is challenging. In this study, we prepared an effective peroxymonosulphate (PMS) activation catalyst derived from sawdust containing calcium carbonate. The Co and Cu co-doped sawdust biochar (CoO/CuO@CBC) catalyst could activate PMS quickly, and the degradation rate of BPA reached 99.3% in 5 min, while the rate constant was approximately 30 times higher than in the CBC/PMS and CoCuOx/PMS systems. Moreover, the interaction between CoO, CuO, and CBC endows the CoO/CuO@CBC catalyst with excellent catalytic performance under different conditions, such as initial pH, temperature, water matrix, inorganic anions, and humic acid, which maintained fast PMS activation via the cyclic transformation of Cu and Co for BPA degradation. The results demonstrated that both the radical (•O2- and •SO4-) and non-radical (1O2) pathways participate in the degradation of BPA in the CoO/CuO@CBC/PMS system. The efficient and stable degradation over a wide range of pH, temperature, and aqueous matrices indicates the potential application of the CoO/CuO@CBC catalyst.

Sustainable upcycling of copper from waste printed circuit boards with the assistance of tannic acid and Fe3+ to a magnetic heterogeneous catalyst

The recovery and upcycling of metals from electronic waste into functional materials for wastewater treatment is a win-win strategy for simultaneously realizing electronic waste recycling and wastewater purification. This study focused on converting Cu from waste printed boards (PCBs), a common Cu-rich electronic waste, into CuFe2O4 supported on a mesoporous carbon framework (PCFT) with the assistance of Fe3+ and tannic acid (TA). Compared to the PCF prepared without TA, the resulting PCFT exhibited excellent magnetic properties, high crystallinity, lower interfacial transfer resistance, more abundant oxygen vacancies (OV), and lower metal leaching. Moreover, PCFT can serve as a superior heterogeneous catalyst to activate peroxymonosulfate to remove reactive brilliant blue KN-R from wastewater, and its catalytic activity was markedly higher than that of CFT synthesized with Cu(NO3)2·3H2O, which may be due to its higher specific surface area and more abundant OV. The combined results of scavenging experiments, electron paramagnetic resonance analysis, and electrochemical measurements implied that both radical and nonradical processes promoted the elimination of KN-R; however, •OH and SO4•- were not the major contributors. Furthermore, the PCFT exhibited high adaptability to pH and water matrices, confirming its practical application potential. These findings provide a novel strategy for the upcycling of metals from electronic waste.

Metal-Organic Framework-Based Nanostructures for Electrochemical Sensing of Sweat Biomarkers

Sweat is considered the most promising candidate to replace conventional blood samples for noninvasive sensing. There are many tools and optical and electrochemical methods that can be used for detecting sweat biomarkers. Electrochemical methods are known for their simplicity and cost-effectiveness. However, they need to be optimized in terms of selectivity and catalytic activity. Therefore, electrode modifiers such as nanostructures and metal-organic frameworks (MOFs) or combinations of them were examined for boosting the performance of the electrochemical sensors. The MOF structures can be prepared by hydrothermal/solvothermal, sonochemical, microwave synthesis, mechanochemical, and electrochemical methods. Additionally, MOF nanostructures can be prepared by controlling the synthesis conditions or mixing bulk MOFs with nanoparticles (NPs). In this review, we spotlight the previously examined MOF-based nanostructures as well as promising ones for the electrochemical determination of sweat biomarkers. The presence of NPs strongly improves the electrical conductivity of MOF structures, which are known for their poor conductivity. Specifically, Cu-MOF and Co-MOF nanostructures were used for detecting sweat biomarkers with the lowest detection limits. Different electrochemical methods, such as amperometric, voltammetric, and photoelectrochemical, were used for monitoring the signal of sweat biomarkers. Overall, these materials are brilliant electrode modifiers for the determination of sweat biomarkers.

Highly efficient targeted adsorption and catalytic degradation of ciprofloxacin by a novel molecularly imprinted bimetallic MOFs catalyst for persulfate activation

Given the presence of emerging pollutants at low concentrations in water bodies, which are inevitably affected by background substances during the removal process. In this study, we synthesized molecularly imprinted catalysts (Cu/Ni-MOFs@MIP) based on bimetallic metal-organic frameworks for the targeted degradation of ciprofloxacin (CIP) in advanced oxidation processes (AOPs). The electrostatic interaction and functional group binding of CIP with specific recognition sites on Cu/Ni-MOFs@MIP produced excellent selective recognition (Qmax was 14.82 mg g-1), which enabled the active radicals to approach and remove the contaminants faster. Electron paramagnetic resonance (EPR) analysis and quenching experiments revealed the coexistence of ∙OH, SO42-, and 1O2, with ∙OH dominating the system. Based on experimental and theoretical calculations, the reaction sites of CIP were predicted and the possible degradation pathways and mechanisms of Cu/Ni-MOFs@MIP/PMS systems were proposed. This study opens up a new platform for the targeted removal of target pollutants in AOPs.

Progress in the Elimination of Organic Contaminants in Wastewater by Activation Persulfate over Iron-Based Metal-Organic Frameworks

The release of organic contaminants has grown to be a major environmental concern and a threat to the ecology of water bodies. Persulfate-based Advanced Oxidation Technology (PAOT) is effective at eliminating hazardous pollutants and has an extensive spectrum of applications. Iron-based metal-organic frameworks (Fe-MOFs) and their derivatives have exhibited great advantages in activating persulfate for wastewater treatment. In this article, we provide a comprehensive review of recent research progress on the significant potential of Fe-MOFs for removing antibiotics, organic dyes, phenols, and other contaminants from aqueous environments. Firstly, multiple approaches for preparing Fe-MOFs, including the MIL and ZIF series were introduced. Subsequently, removal performance of pollutants such as antibiotics of sulfonamides and tetracyclines (TC), organic dyes of rhodamine B (RhB) and acid orange 7 (AO7), phenols of phenol and bisphenol A (BPA) by various Fe-MOFs was compared. Finally, different degradation mechanisms, encompassing free radical degradation pathways and non-free radical degradation pathways were elucidated. This review explores the synthesis methods of Fe-MOFs and their application in removing organic pollutants from water bodies, providing insights for further refining the preparation of Fe-MOFs.