Enhancement of aqueous stability of NH2-MIL-101(Fe) by hydrophobic grafting post-synthetic modification

The design and preparation of PDI modified NH2-MIL-101(Fe) for high efficiency removal of dimethoate in peroxymonosulfate system: Performance, mechanism, pathway and toxicity assessment

The widespread use of organophosphorus pesticide dimethoate (DMT) in agriculture poses a threat to human health. In this work, the perylene tetracarboxylic diimide (PDI) modified NH2-MIL-101(Fe) (PDI/MIL) with strong covalent bond C(=O)-N were designed and prepared by a step solvothermal method. The synergistic effect between photocatalytic and peroxymonosulfate (PMS) activation for the DMT elimination over PDI/MIL was gained. Interestingly, PDI/MIL(1:10)/PMS showed boosting degradation efficiency (95.6%) for DMT under 18 min simulated sunlight irradiation. Its apparent reaction rate constant was 24.7 times higher than that of NH2-MIL-101(Fe)/PMS. Moreover, its reusability, stability and mineralization ability were evaluated, and a remarkable mineralization rate of 95.3% with 90 min was achieved. The enhanced activity were attributed to the formation of amide bond that exhibited superior charger transport ability and amount of produced active species. Combined the results obtained from the HPLC-MS and molecular structure characteristics of DMT analyzed by Fukui index, the degradation pathways were proposed. The toxicity of intermediates were predicted by Ecological Structure Activity Relationship (ECOSAR), Toxicity Estimation Software Tool (T.E.S.T.), and Vibrio fischeri experiments. Our work provided deep insights into the mechanisms of DMT degradation via photocatalysis-activated PMS over organic semiconductor modified metal organic frameworks.

Engineering cellulose aerogel composites for mercury ion sequestration and aquatic real time monitoring based on the immobilization of metal-organic frameworks

Industrial wastewater effluents containing elevated levels of mercury are a significant menace to both the ecosystem and human health. Despite the advent of metal-organic frameworks (MOFs) as promising adsorbents, their application in treatment of industrial wastewater has been impeded by the challenges associated with handling their powdered form. In this work, we introduce a straightforward method for fabricating MOF composite cellulose aerogels (5MM-101@CA). The resulting adsorbent showed a high adsorption capacity of 409.84 mg/g for Hg (II), with over 75 % removal efficiency maintained after five consecutive adsorption-desorption cycles. Furthermore, the material exhibited high sensitivity for the real-time detection of Hg (II), with a detection limit as low as 6.89×10-8 M. The adsorbent also showed remarkable fluorescence stability for up to a week, indicative of its excellent optical performance. Dynamic adsorption demonstrated the adsorbent's ability to sustain continuous and stable system operation without compromising adsorption efficiency. These findings underscore the effectiveness of post-synthetic modification (PSM) technology in enhancing the performance of MOFs, while highlighting the utility of low-cost cellulose as an effective carrier. Thus, the composite material developed in this work is promising as it not only maximizes the adsorption capabilities of MOFs but also circumvents the risk of secondary pollution.

One-pot synthesis of bimetallic Fe-Cu metal-organic frameworks composite for the elimination of organic pollutants via peroxymonosulphate activation

A series of bimetallic of FeCu metal-organic frameworks (MOFs) have been synthesised using a solvothermal process by varying the ratio between the two metals. Further, the bimetallic MOF catalysts were characterised by X-ray powder diffraction, scanning electron microscopy, and infrared spectroscopy techniques. Their catalytic properties for activation of peroxymonosulphate (PMS) have been tested by the removal of a model dye, rhodamine B. As a result, NH2-Fe2.4Cu1-MOF demonstrated the highest degradation, the effect of the ratio NH2-Fe2.4Cu1-MOF/PMS has been studied, and the main reactive species have been assessed. The application of these MOFs in powder form is difficult to handle in successive batch or flow systems. Thus, this study assessed the feasibility of growing NH2-Fe2,4Cu1-MOF on polyacrylonitrile (PAN) spheres using the one-pot solvothermal synthesis method. The optimisation of the catalytic activity of the synthesised composite (NH2-Fe2.4Cu1-MOF@PAN) has been evaluated by response surface methodology using a central composite face-centred experimental design matrix and selecting as independent variables: time, PMS concentration, and catalyst dosage. Based on the results, the optimisation of the operational conditions has been validated. At 2.5 mM PMS, 90 min, and 1.19 g·L-1 of catalyst dosage, maximum degradation (80.92%) has been achieved, which doubles the removal values obtained in previous studies with other MOFs. In addition, under these conditions, the catalyst has been proven to maintain its activity and stability for several cycles without activity loss.

Application of Fe-MOFs in Photodegradation and Removal of Air and Water Pollutants: A Review

Photocatalytic technology has received increasing attention in recent years. A pivotal facet of photocatalytic technology lies in the development of photocatalysts. Porous metal-organic framework (MOF) materials, distinguished by their unique properties and structural characteristics, have emerged as a focal point of research in the field, finding widespread application in the photo-treatment and conversion of various substances. Fe-based MOFs have attained particular prominence. This review explores recent advances in the photocatalytic degradation of aqueous and gaseous substances. Furthermore, it delves into the interaction between the active sites of Fe-MOFs and pollutants, offering deeper insights into their mechanism of action. Fe-MOFs, as photocatalysts, predominantly facilitate pollutant removal through redox processes, interaction with acid sites, the formation of complexes with composite metal elements, binding to unsaturated metal ligands (CUSs), and hydrogen bonding to modulate their respiratory behavior. This review also highlights the focal points of future research, elucidating the challenges and opportunities that lie ahead in harnessing the characteristics and advantages of Fe-MOF composite catalysts. In essence, this review provides a comprehensive summary of research progress on Fe-MOF-based catalysts, aiming to serve as a guiding reference for other catalytic processes.

Superhydrophobic MOFs with enhanced catalytic activity for chemical fixation of CO2

A general approach to prepare superhydrophobic MOFs (denoted as MOFs-CF3) through a post-decorating strategy for highly efficient chemical fixation of CO2 was demonstrated. The enhanced catalytic activity of MOFs-CF3 is attributed to a synergistic effect between the Lewis acid sites of MOFs and modification of the electron-withdrawing trifluoromethyl group, which resulted in a high CO2 enrichment capacity. The possible mechanism of cycloaddition catalyzed by the MOFs-CF3 catalyst was also proposed.

A Dual-Mode NADH Biosensor Based on Gold Nanostars Decorated CoFe2 Metal-Organic Frameworks to Reveal Dynamics of Cell Metabolism

Nicotinamide adenine dinucleotide (NADH) is central to metabolism and implicated in various diseases. Herein, nanohybrids of gold nanostars and metal-organic frameworks are devised and demonstrated as a dual-mode NADH sensor, for which colorimetric detection is enabled by its peroxidase-like nanozyme property and Raman detection is realized by its surface-enhanced Raman scattering property with the detection limit as low as 28 pM. More importantly, this probe enables real-time SERS monitoring in living cells, providing a unique tool to investigate dynamic cellular processes involving NADH. Our experiments reveal that metabolism dynamics is accelerated by glucose and is much higher in cancerous cells. The SERS results can also be verified by the colorimetric detection. This sensor provides a new potential to detect biomarkers and their dynamics in situ.