Search Results (319)

Catalytic ozonation has been widely utilized in environmental applications, such as the removal of pharmaceutical active compounds (PHACs) from wastewater, due to its outstanding catalytic efficiency. To further enhance its performance and expand its practical application, ozone-based hybrid processes have been investigated, including ultraviolet radiation/ozonation, hydrogen peroxide/ozonation, ultrasonication/ozonation, and biological treatment/ozonation. Ozone degrades pollutants via two primary pathways: direct oxidation (via molecular ozone) and indirect oxidation (via reactive intermediates). Enhancing ozone decomposition into various reactive oxygen species (ROS), predominantly hydroxyl radicals, can significantly augment the degradation efficiency of pollutants. The surface adsorption and electron transfer processes of catalysts can promote ozone activation and decomposition into ROS to achieve the efficient degradation and mineralization of pollutants. Among catalysts, Mn-based catalysts have been extensively studied in past research. They have demonstrated exceptional performance when combined with other metals, such as Mn/Ce, Mn/Fe, and Mn/Co, etc., due to synergistic effects arising from bimetallic interactions. The inherent characteristics of catalyst supports may also influence the generation process of ROS. Choosing an appropriate support is conducive to promoting the uniform distribution of catalytic active sites on the catalyst surface and avoiding the agglomeration of metal particles, and it is also beneficial for the recovery and reuse of the catalyst. Furthermore, coupling catalytic ozonation processes with techniques like high-gravity technology, jet reactor systems, and micro–nano-bubbles can improve the utilization efficiency of ozone by exploiting gas cavitation effects. In this paper, we summarize the research progress in the degradation of PHACs using catalytic ozonation and discuss strategies for improving the mass transfer efficiency of ozone in water. Finally, the challenges and opportunities associated with applying catalytic ozonation in practical applications are also discussed. Full article

In today’s world, environmental projects that contribute to the protection of water resources are needed due to the ongoing deterioration caused by the discharge of heavy metals, especially chromium. One way to investigate this problem is to use adsorbent biomasses, such as bacterial cellulose. This cellulose is increasingly popular due to its ability to chemisorb heavy metals present in water. Furthermore, the addition of iron chloride to this biomass improves its performance, creating more active sites and thus increasing its heavy metal adsorption capacity. Due to the promising results, pilot-scale research with physical models in fixed biomass columns has gained relevance, and adsorption isotherms could be used to adjust these models and optimize the design of these prototypes. For this reason, a project to treat water contaminated with Cr(VI) using bacterial cellulose and FeCl₃ in a continuous system was created. Experiments were conducted with different concentrations, and treatment conditions were established based on the isotherms. Subsequently, elutions with EDTA were performed up to six times to allow biomass reuse in the continuous system with a bacterial cellulose column containing iron chloride. This achieved a total adsorption capacity of 626 mg/g, summing the six treatment cycles. The results provide practical parameters and evidence to support future studies to scale up and optimize Cr(VI) effluent treatment. Full article

The synthesis and electrocatalytic properties of amorphous first- and third-row transition metal sulfides (a-TMS) for green hydrogen generation have been comprehensively reviewed. These electrocatalysts can be prepared by several solution processes, including chemical bath deposition, electrodeposition, sol–gel, hydrothermal reaction and thermolysis. The deposition method strongly influences the electrochemical properties of the synthesized a-TMS electrocatalyst. Based on overpotential at 10 mA/cm², the electrocatalytic activity of mono-metallic a-TMS for hydrogen evolution is ranked as follows: a-NiS_x > a-CuS_x > a-CoS_x > a-WS_x > a-FeS_x. The best performing a-NiS_x prepared by chemical bath deposition has an overpotential at 10 mA/cm² of 53 mV and Tafel slope of 68 mV/dec in 1 M KOH electrolyte. The integration of Ni into the a-TMS network structure is crucial to achieving high activity in multi-metallic a-TMS electrocatalyst, as demonstrated by the bifunctional (NiFe)S_x/NiFe(OH)_y nanocomposite catalyst. The critical role of Ni in a-TMS catalyst design can be attributed to the lower free energy change for hydrogen adsorption on Ni. Finally, the emerging catalyst design strategy of amorphous–crystalline heterostructures with a three-dimensional morphology will be discussed together with the need to identify hydrogen adsorption sites on a-TMS electrocatalysts in future. Full article

In this study, we investigate the catalytic degradation of polystyrene (PS) in water at low temperature (90–110 °C, 1 atm) using a multiphase carbide–alloy catalyst obtained by mechanosynthesis. X-ray diffraction and scanning electron microscopy confirm a mixture of Mo–W carbides and Fe/Ni alloys, consistent with multiple types of active sites. High-resolution mass spectrometry (MS) is used to assign products by oligomer-series spacing (styrene repeat mass, 104.15 Da) and the residual mass $\Delta m$ for end-group identification. At 90 °C without catalyst, the spectrum shows PS fragments between $m/z=888$–4618, consistent with thermal depolymerization. With catalyst at 90 °C, new lower-$m/z$ peaks emerge and long-chain signals diminish, indicating enhanced chain scission under mild conditions. Increasing the temperature to 100 and 110 °C yields even lighter ions (e.g., $m/z=307.59$ and 247.88), confirming stronger cracking and a larger number of distinct products. End groups inferred from $\Delta m$ include alkenes (C₃–C₇), alkanes (C₄, C₇), cyclic C₆–C₇ fragments, and alcohols, which are consistent with protolytic C–C bond cleavage (Haag–Dessau), oxidative dehydrogenation, and subsequent hydrogenation/hydration on metal/carbide sites. Overall, the results show that water-activated carbide–alloy catalysts can drive PS deconstruction at low temperature, shifting products toward shorter chains with useful functional groups, while a simple MS-based rule set provides a transparent and reproducible approach to product assignment. Full article

Cobalt-based Prussian blue hollow spheres (CoHCF HSs) with different Co contents were synthesized using a self-templated coprecipitation technology. The microstructure and electrochemical properties of CoHCF HSs were investigated. The results indicate that all samples exhibit a face-centered cubic crystal structure. With increasing cobalt content in the Prussian blue analogues, the X-ray diffraction peaks shift toward higher angles due to the reduction in interplanar spacing. Computer simulations revealed that Na⁺ ions exhibit higher adsorption energies (ΔE_a) at Co sites (ΔE_a = 1.45 eV) compared to Fe sites (ΔE_a = 1.18 eV), which enables Co sites to adsorb more Na⁺ ions, providing greater sodium storage capacity. With increasing cobalt content, the reduced aspect ratio of CoHCF HSs surface nanoscale protrusions decreases the specific surface area. Consequently, the overall average CoHCF HSs size decreases with increasing cobalt content, which predominates the increase in specific surface area, contributing to supplying more active sites. The best electrochemical properties showed an initial capacity of 121.16 mAh g⁻¹ at a current density of 0.2 A g⁻¹ but not at the largest specific surface area. These findings suggest that improving the electrochemical performance of CoHCF electrodes requires consideration of the synergistic effects between specific surface area and elemental composition. Full article

Human DNA dioxygenase ABH2 is a key enzyme of the AlkB family of Fe(II)/α-ketoglutarate-dependent oxygenases, which is specialized in removing alkyl groups from damaged DNA bases in the cell nucleus. At the same time, the occurrence of single-nucleotide polymorphisms (SNPs) in the human ABH2 gene can lead to amino acid substitutions that, in turn, may disrupt the normal functioning of the ABH2 enzyme. Currently, databases contain information about more than 2500 nucleotide substitutions in the ABH2 gene. Using a comprehensive bioinformatics approach, in this review, we analyzed over 200 non-synonymous ABH2 SNPs with eleven prediction programs to identify variants capable of negatively affecting its enzymatic activity. The combination of various programs with different evaluation algorithms and scoring approaches allows us to more reliably identify potentially deleterious amino acid substitutions. Moreover, the differences between the programs used allowed for comparison of their tendency to predict amino acid substitutions as deleterious. Structural analysis of the ABH2-substrate complex showed that selected functionally significant SNPs often affect the organization of the active site, reduce the efficiency of substrate binding, and/or disrupt the coordination of Fe²⁺ and α-ketoglutarate cofactors, leading to changes in catalytic efficiency. The data obtained from the conducted analysis suggest that naturally occurring polymorphisms in the ABH2 gene found in the human population may reduce the repair efficiency of DNA dioxygenase ABH2 and, consequently, modulate susceptibility to oncogenesis and influence the effectiveness of antitumor therapy for carriers of these SNPs. Full article

Tetracycline (TC) is chemically stable and recalcitrant to natural degradation. Peroxymonosulfate (PMS)-based advanced oxidation processes offer an effective removal strategy, the efficacy of which relies on high-performance heterogeneous catalysts. Titanium dioxide (TiO₂) is an ideal material due to its stability and environmental compatibility, yet its practical application is hindered by inadequate PMS activation capacity, particle agglomeration, and difficult recovery. To address these limitations, a heterogeneous Fe/TiO₂ catalyst was constructed via Fe³⁺ doping, innovatively utilizing polyvinylpyrrolidone (PVP) as a structure-directing agent. PVP’s steric hindrance effectively suppressed nanoparticle agglomeration and enabled high dispersion of Fe active sites, simultaneously enhancing catalytic activity and stability. Under optimized conditions, the Fe/TiO₂/PMS system achieved 94.3% TC degradation, following pseudo-first-order kinetics and significantly outperforming pure TiO₂ used in this experimental system. Radical quenching verified sulfate radicals (SO₄•⁻) as the dominant species. The catalyst demonstrated excellent recyclability, retaining over 80% degradation efficiency after six cycles and enabling convenient magnetic separation. Moreover, in complex water matrices (tap water and seawater), it sustained high removal efficiency (>90% initially, >70% after six cycles), highlighting its superior anti-interference capability and practical potential. This work offers a strategic material design strategy for efficient and robust TC removal in challenging water environments. Full article

The removal of synthetic dyes from industrial effluents remains challenging due to their chemical stability and poor biodegradability. Here we engineer metal-doped carbon dots (CDs) as heterogeneous Fenton-like catalysts and elucidate how dopant identity governs structure–activity relationships and reactive oxygen species (ROS) pathways. Fe-, Cu-, Zn- and Mg-doped CDs were prepared via a one-pot hydrothermal route and comprehensively characterised by TEM, FTIR, XPS and zeta-potential analysis. The resulting nanoparticles displayed narrow size distributions (10.2–15.2 nm) and dopant-dependent surface chemistries and charges. Catalytic tests with methylene blue (MB) and rhodamine B (RB) show that Fe-doped CDs deliver the highest activity toward MB degradation (k = 0.0218 min⁻¹), attributable to efficient Fe²⁺/Fe³⁺ redox cycling coupled with hydroxyl-rich surfaces that promote H₂O₂ activation. Zn-doped CDs achieve complete RB decolourisation under Fenton-like conditions, which we ascribe to their higher surface charge and abundant oxygenated sites that enhance pollutant adsorption and ROS generation. Cu- and Mg-doped CDs exhibit intermediate and dopant-specific performances consistent with their respective redox and adsorption characteristics. Collectively, these results establish clear correlations between dopant chemistry, surface functionality, and ROS formation routes, providing mechanistic guidance for the rational design of carbon-based Fenton catalysts for sustainable water remediation. Full article

The recalcitrance and biological toxicity of phenolic pollutants pose a serious threat to the safety of aquatic environments, and developing efficient and stable catalytic degradation technologies is a key research focus in the current environmental field. In this study, a composite material (MSN) of NH₂-MIL-101(Fe) modified by MoSe₂ nanosheets was constructed via a one-step composite strategy, aiming to address the bottlenecks of low Fe³⁺/Fe²⁺ cycling efficiency and iron ion leaching in traditional Fe-based MOFs when activating peroxymonosulfate (PMS). Characterization results showed that MoSe₂ nanosheets were uniformly dispersed on the surface of NH₂-MIL-101(Fe), and strong electronic interactions existed between them, which significantly optimized the electronic environment of active sites. MSN-3 exhibited excellent performance in activating PMS for phenol degradation: the degradation rate reached 90% within 30 min, with a k = 0.073 min⁻¹, which was much higher than that of other systems. It also showed good structural stability and cyclic regeneration ability. Mechanistic studies confirmed that the core active species in the MSN-3/PMS system are ¹O₂, •SO₄⁻ and •OH. The two-dimensional layered structure of MoSe₂ can serve as an efficient electron transport bridge to promote Fe³⁺/Fe²⁺ cycling; amino modification further optimizes the electron density of Fe active centers. The two synergistically construct a dual redox cycle of Fe³⁺/Fe²⁺ and Mo⁴⁺/Mo⁶⁺, significantly enhancing PMS activation efficiency and ¹O₂ production. This study provides a new strategy for designing Fe-MOFs-based PMS activation catalysts and also offers technical support for the practical treatment of recalcitrant organic pollutants in water. Full article

Electrocatalytic water splitting offers a promising route to sustainable H₂, but the oxygen evolution reaction (OER) in alkaline media remains the principal bottleneck for activity and durability. This review focuses on alkaline OER and integrates mechanism, kinetics, materials design, and cell-level considerations. Reaction mechanisms are outlined, including the adsorbate evolution mechanism (AEM) and the lattice oxygen mediated mechanism (LOM), together with universal scaling constraints and operando reconstruction of precatalysts into active oxyhydroxides. Strategies for electronic tuning, defect creation, and heterointerface design are linked to measurable kinetics, including iR-corrected overpotential, Tafel slope, charge transfer resistance, and electrochemically active surface area (ECSA). Representative catalyst families are critically evaluated, covering Ir and Ru oxides, Ni-, Fe-, and Co-based compounds, carbon-based materials, and heterostructure systems. Electrolyte engineering is discussed, including control of Fe impurities and cation and anion effects, and gas management at current densities of 100–500 mA·cm⁻² and higher. Finally, we outline challenges and directions that include operando discrimination between mechanisms and possible crossover between AEM and LOM, strategies to relax scaling relations using dual sites and interfacial water control, and constant potential modeling with explicit solvation and electric fields to enable efficient, scalable alkaline electrolyzers. Full article

Gas turbines operate at exhaust gas temperatures exceeding 500 °C. Vanadium-based catalysts encounter challenges in NH₃-SCR denitrification due to vanadium volatilization and titanium dioxide support phase transition at high temperatures. This restricts the effective denitrification temperature range to 300~400 °C, falling short of gas turbine denitrification requirements. Zeolite-supported catalysts, known for their high specific surface area, abundant acid sites, and stable framework structure, demonstrate superior catalytic activity and hydrothermal stability at high temperatures. This review synthesizes recent advancements in high-temperature catalysts utilizing ZSM-5, Beta, SSZ-13, and SAPO-34 zeolites as supports. It elucidates the interaction mechanisms between active components (e.g., transition metals Fe, Cu, W, rare earth elements) and zeolite supports. Furthermore, it examines variations in denitrification performance through the lens of the high-temperature NH₃-SCR reaction mechanism, offering valuable insights for high-temperature denitrification catalyst development. Full article

The increasing demand for sustainable chemical processes has fostered the development of advanced catalytic systems for biomass valorization. In this work, a series of mono-, bi-, and trimetallic oxides (FeO, FeCuO, FeZnO, and FeCuZnO) were successfully synthesized using MIL-101-based MOFs as sacrificial templates. The obtained materials were thoroughly characterized by N₂ adsorption–desorption, XRD, FTIR, and TEM/STEM-EDX to investigate their structural, morphological, and textural properties. Their catalytic performance was evaluated in the selective oxidation of benzyl alcohol, a lignin-derived platform molecule, into benzaldehyde under microwave irradiation as a sustainable heating strategy. The results demonstrate that MOF-derived oxides exhibit superior activity compared to their parent MOFs, highlighting the beneficial effect of thermal treatment on the exposure of active sites. Among the catalysts, heterometallic oxides showed enhanced performance due to synergistic effects between metals. In particular, FeZnO reached a maximum yield of 62.1% towards benzaldehyde at 150 °C and 30 min, outperforming the monometallic oxide. Recycling tests revealed that FeZnO retained higher overall performance than FeCuO, which suffered from progressive copper leaching. These findings confirm the potential of MOF-derived multimetallic oxides as efficient and reusable heterogeneous catalysts for selective biomass-derived alcohol oxidation. The combination of microwave-assisted processes and the tuneable nature of MOF-derived oxides provides a promising pathway for designing sustainable catalytic systems with industrial relevance. Full article

In this study, insoluble CaSO₃ was applied to replace soluble sulfite/bisulfite salt in the Fe(II)-activated sulfite/bisulfite [S(IV)] process for the efficient 2,4,6-tribromophenol (TBP) degradation. CaSO₃ serves as a low-cost and slow-release source of S(IV), significantly improving S(IV) utilization compared to conventional soluble Na₂SO₃. The Fe(II)/CaSO₃ system generated SO₄^•− and HO^• through Fe(II)/Fe(III) redox cycling. Mechanistic studies confirmed SO₄^•− as the dominant reactive species, selectively attacking C-Br bonds and hydroxyl groups in TBP. Process optimization revealed effective performance under acidic conditions (pH 3.5–4.0) with minimal inhibition by common anions (Cl⁻, HCO₃⁻). The reactive sites of TBP were identified through Fukui function calculations, and the degradation pathway was elucidated based on LC-MS analysis. Toxicity evaluation indicated reduced ecological risk of degradation intermediates due to debromination and benzene ring cleavage. This work provides a sustainable strategy for efficient TBP removal and detoxification in wastewater treatment with benefiting S(IV) utilization. Full article

Fe–Ce-MOFs with a rice-grain-like morphology were successfully obtained via hydrothermal synthesis, where ferric chloride (FeCl₃) and cerium nitrate [Ce(NO₃)₃] served as the metal precursors and terephthalic acid (PTA) acted as the organic coordinating ligand. The effects of the Fe:Ce molar ratio, (Fe/Ce):PTA ratio, reaction duration, and synthesis temperature on adsorption performance of the Fe–Ce-MOFs were systematically studied. A comprehensive evaluation was conducted on the removal of fluoride and phosphate ions from aqueous solution. Under optimized conditions, the maximum adsorption capacities of Fe–Ce-MOFs for fluoride and phosphate reached 183.82 mg g⁻¹ and 110.74 mg g⁻¹, respectively. Adsorption data correlated strongly with the Langmuir isotherm, were best represented by the pseudo-second-order kinetic model, and were identified as a spontaneous and endothermic reaction. After three regeneration cycles, the adsorbent still maintained high removal efficiencies for fluoride (85.17%) and phosphate (47.34%) removal. In practical wastewater treatment, removal efficiencies of 92.04% for fluoride and 93.87% for phosphate were achieved. Mechanistic studies revealed that fluoride removal was dominated by electrostatic attraction and hydroxyl–fluoride ion exchange, whereas phosphate removal was attributed to the generation of inner-sphere complexes involving PO₄³⁻ and Fe/Ce active sites. This study not only elucidates the synergistic mechanism of fluoride and phosphate elimination by Fe–Ce-MOFs but also provides theoretical guidance and application prospects for the development of highly efficient and stable bimetallic MOF-based adsorbents for environmental remediation. Full article

This study presents a novel dual-temperature synthesis strategy for cobalt, zinc, and iron-based metal–organic frameworks (MOFs) integrated with tannic acid (TA) surface modification to enhance oxygen evolution reaction (OER) performance. MOFs were synthesized at room temperature and 80 °C, enabling controlled crystal growth and distinct morphologies. Subsequent TA treatment effectively tuned surface chemistry without altering core crystallinity, as confirmed by PXRD, FT-IR, and XPS analyses. Surface modification introduced oxygen-containing functional groups, improved charge transfer, and increased active-site accessibility. Among the catalysts, the tannic acid-modified Fe-based MOF synthesized at 80 °C (TAFeM-2) exhibited outstanding OER activity, achieving an overpotential of only 254 mV at 10 mA cm⁻², outperforming benchmark RuO₂ (276 mV) and unmodified counterparts. Tafel slope analysis revealed faster reaction kinetics for surface-tuned MOFs, while electrochemical impedance spectroscopy indicated reduced charge-transfer resistance (12 Ω for TAFeM-2). Chronoamperometry demonstrated exceptional long-term stability, maintaining constant current density over 20 h with minimal performance loss. Post-OER characterization suggested surface oxidation to iron oxyhydroxides without significant structural degradation. This work demonstrates that combining dual-temperature synthesis with TA surface engineering yields MOF-based catalysts with superior activity, conductivity, and durability, offering a promising pathway for developing high-performance electrocatalysts for sustainable energy applications. Full article