Search Results (39)

To mitigate the consumption of active sites on co-catalysts by H₂O₂ and to enhance the efficiency and stability of co-catalytic Fenton reactions, an external circulation two-stage packed-bed reactor (ECTPBR) was developed using DPW (diatomite plate@polydopamine@WC) as a co-catalyst to degrade 4-nitrophenol (4-NP). Under suitable conditions, the ECTPBR could achieve over 91.97% 4-NP degradation, with low iron sludge production (11.97 mg/L) and minimal tungsten leaching (3.6363 mg/L). The two-stage strategy enabled spatial separation of Fe³⁺ reduction and Fenton reactions, minimizing the loss of active sites on DPW, ensuring long-term system stability, and reducing the toxicity of 4-NPdegradation products. In addition, external circulation enhanced mass transfer and improved resistance to shock loads. These advantages suggest that the ECTPBR may serve as an effective strategy for applying co-catalytic Fenton reactions in the treatment of toxic and refractory organic wastewater. Full article

In this investigation, a hierarchical FeCo-layered double hydroxide (FeCo-LDH) electrochemical membrane material was prepared by a simple in situ hydrothermal method. The prepared material formed a 3D honeycomb-structured FeCo-LDH-modified carbon felt (FeCo-LDH/CF) catalytic layer with uniform open pores on a CF substrate with excellent catalytic activity and was served as the cathode in a flow-through electro-Fenton (FTEF) reactor. The electrocatalyst demonstrated excellent treatment performance (99%) in phenol simulated wastewater (30 mg L⁻¹) under the optimized operating conditions (applied voltage = 3.5 V, pH = 6, influent flow rate = 15 mL min⁻¹) of the FTEF system. The high removal rate could be attributed to (i) the excellent electrocatalytic oxidation performance and low interfacial charge transfer resistance of the FeCo-LDH/CF electrode as the cathode, (ii) the ability of the synthesized FeCo-LDH to effectively promote the conversion of H₂O₂ to •OH under certain conditions, and (iii) the flow-through system improving the mass transfer efficiency. In addition, the degradation process of pollutants within the FTEF system was additionally illustrated by the •OH dominant ROS pathway based on free radical burst experiments and electron paramagnetic resonance tests. This study may provide new insights to explore reaction mechanisms in FTEF systems. Full article

Antibiotic resistance has been recognized as a global threat to human health. Therefore, it is urgent to develop effective strategies to address the contamination of water environments caused by antibiotics. In this study, Fe/Mn bimetallic-modified biochar (FMBC) was synthesized through a one-pot oxidation/reduction-hydrothermal co-precipitation method, demonstrating an exceptional photocatalytic-Fenton degradation performance for oxytetracycline (OTC). Characterization techniques including FTIR, SEM, XRD, VSM, and N₂ adsorption–desorption analysis confirmed that the Fe/Mn bimetals were successfully loaded onto the surface of biochar in the form of Fe₃O₄ and MnFe₂O₄ mixed crystals and exhibited favorable paramagnetic properties that facilitate magnetic recovery. A key innovation is the utilization of biochar’s inherent phenol/quinone structures as reactive sites and electron transfer mediators, which synergistically interact with the loaded bimetallic oxides to significantly enhance the generation of highly reactive ·OH radicals, thereby boosting catalytic activity. Even after five recycling cycles, the material exhibited minimal changes in degradation efficiency and bimetallic crystal structure, indicating its notable stability and reusability. The photocatalytic degradation experiment conducted in a Fenton-like reaction system demonstrates that, under the conditions of pH 4.0, a H₂O₂ concentration of 5.16 mmol/L, a catalyst dosage of 0.20 g/L, and an OTC concentration of 100 mg/L, the optimal degradation efficiency of 98.3% can be achieved. Additionally, the pseudo-first-order kinetic rate constant was determined to be 4.88 min⁻¹. Furthermore, this study elucidated the detailed degradation mechanisms, pathways, and the influence of various ions, providing valuable theoretical insights and technical support for the degradation of antibiotics in real wastewater. Full article

The widespread contamination of aquatic environments by tetracycline antibiotics (TCs) poses a substantial threat to public health and ecosystem stability. Although photo-Fenton processes have demonstrated remarkable efficacy in degrading TCs, their practical application is limited by challenges associated with catalyst recyclability. This study reports the development of a novel magnetic recoverable SrFe₁₂O₁₉/g-C₃N₄ heterostructure photocatalyst synthesized via a facile one-step co-calcination method using industrial-grade precursors. Comprehensive characterization revealed that nitrogen defects and the formation of heterojunction structures significantly suppress electron (e⁻)–hole (h⁺) pair recombination, thereby markedly enhancing catalytic activity. The optimized 7-SFO/CN composite removes over 90% of oxytetracycline (OTC) within 60 min, achieving degradation rate constants of 0.0393 min⁻¹, which are 9.1 times higher than those of SrFe₁₂O₁₉ (0.0043 min⁻¹) and 4.2 times higher than those of g-C₃N₄ (0.0094 min⁻¹). The effectively separated e⁻ play three critical roles: (i) directly activating H₂O₂ to generate ·OH radicals, (ii) promoting the redox cycling of Fe²⁺/Fe³⁺ ions, and (iii) reducing dissolved oxygen to form ·O₂⁻ species. Concurrently, h⁺ directly oxidize OTC molecules through surface-mediated reactions. Furthermore, the 7-SFO/CN composite exhibits exceptional operational stability and applicability, offering a transformative approach for scalable photocatalytic water treatment systems. This work provides an effective strategy for designing efficient and recoverable photocatalysts for environmental remediation. Full article

In this study, hydrochars loaded with iron species (Fe@HTC and Fe@HTC−T) were prepared by chemical co-precipitation and tubular furnace sintering treatment to develop efficient and sustainable catalysts for antibiotic wastewater treatment, addressing key challenges in sustainable environmental management. The characterization results indicated that iron species loaded on the hydrochars changed from Fe₃O₄ to FeO and then to metallic Fe with the pyrolysis temperature increased from 400 °C to 800 °C. The results of the characterization revealed a phase transition of iron species, confirming the temperature-dependent evolution of catalytic activity. The catalytic performance of the hydrochar composites was evaluated for tetracycline hydrochloride (TC–HCl) degradation via a Fenton-like process. Under optimal conditions (0.2 g/L TC–HCl, 0.1 g/L catalyst, 0.1 mM H₂O₂, pH = 6.86), Fe@HTC−T demonstrated excellent catalytic activity with a removal efficiency of 91.2%. Moreover, Fe@HTC−T exhibited superior stability and low iron leaching rates, attributed to the protective role of the hydrochar matrix. Mechanism research suggested that hydroxyl radicals (•OH) played a dominant role in the degradation process. This study demonstrates the potential of utilizing low-cost and renewable hydrochar materials derived from biomass waste to address industrial challenges in treating high-concentration antibiotic wastewater, offering a sustainable and cost-effective solution with broad applications in environmental remediation. Full article

An organic–inorganic hybrid polyoxometalate (POM) CoPMoV [PMo^VI₈V^IV₄V^V₂O₄₂][Co(Phen)₂(H₂O)]₂[TEA]₂•H₃O•3H₂O (Phen = 1,10-phenanthroline, TEA = triethylamine) prepared by hydrothermal synthesis was explored as a heterogeneous catalysts to remove methylene blue (MB) through Fenton-like reaction and catalytic reduction. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) were employed to characterize CoPMoV. The MB removal rates for the Fenton-like reaction and the catalytic reduction were 91.6% (120 min) and 97.5% (2 min), respectively, under optimum conditions. CoPMoV demonstrated excellent stability and recyclability in the Fenton-like reaction and catalytic reduction, which was confirmed by 5 cycle tests. Plausible mechanisms for MB degradation and reduction have also been proposed. Benefiting from the excellent redox properties of cobalt and [PMo^VI₈V^IV₄V^V₂O₄₂]⁵⁻ anion, CoPMoV could act as a Fenton-like and reductive catalyst for the removal of MB. This study provides a green and facile strategy to design POM-based organic–inorganic material for dye wastewater treatment via oxidation and reduction. Full article

Formaldehyde (HCHO) is identified as the most toxic chemical among 45 organic compounds found in industrial wastewater, posing significant harm to both the environment and human health. In this study, a novel approach utilizing the Lanthanum-manganese complex oxide (LaMnO₃)/peroxymonosulfate (PMS) system was proposed for the effective removal of HCHO from wastewater. Perovskite-Type LaMnO₃ was prepared by sol-gel method. The chemical compositions and morphology of LaMnO₃ samples were analyzed through thermogravimetric analysis (TG), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The effects of LaMnO₃ dosage, PMS concentration, HCHO concentration, and initial pH on the HCHO removal rate were investigated. When the concentration of HCHO is less than 1.086 mg/mL (5 mL), the dosage of LaMnO₃ is 0.06 g, and n(PMS)/n(HCHO) = 2.5, the removal rate of HCHO is more than 96% in the range of pH = 5–13 at 25 °C for 10 min. Compared with single-component MnO₂, the perovskite structure of LaMnO₃ is beneficial to the catalytic degradation of HCHO by PMS. It is an efficient Fenton-like oxidation process for treating wastewater containing HCHO. The LaMnO₃ promoted the formation of SO₄•⁻ and HO•, which sequentially oxidized HCHO to HCOOH and CO₂. Full article

The composite photocatalyst FeOOH/g-C₃N₄ was prepared through thermal polycondensation and co-precipitation methods, followed by XRD, SEM and UV-vis characterization. The stability of FeOOH/g-C₃N₄ was explored by the recycling test. The active species in the reaction system were investigated by the capture experiment. The results indicated that the optimal preparation condition for g-C₃N₄ involved calcination at 600 °C for 4 h. XRD analysis revealed that g-C₃N₄ exhibits a high-purity phase, and Fe in FeOOH/g-C₃N₄ exists in a highly dispersed amorphous state. SEM analysis showed that FeOOH/g-C₃N₄ has a rough surface with an irregular layered structure. Element composition analysis confirmed that the content of elements in the prepared catalyst is consistent with the theoretical calculation. FeOOH/g-C₃N₄ possesses the largest specific surface area of 143.2 m²/g and a suitable pore distribution. UV-vis DRS analysis showed that the absorption intensity of FeOOH/g-C₃N₄ is stronger than that of g-C₃N₄. When the catalyst dosage was 1.0 g/L, the H₂O₂ dosage was 4 mmol/L, the PNP initial concentration was 10 mg/L and the initial pH value was 5, the PNP removal could reach 92% in 120 min. Even after 5 cycles, the efficiency of PNP removal by FeOOH/g-C₃N₄ remains nearly 80%. The capture experiment indicated that both •OH and •O₂⁻ play roles in the photocatalytic degradation of PNP, with •OH being more significant. These findings affirm that FeOOH has been successfully incorporated into g-C₃N₄, resulting in a conspicuous catalytic effect on the degradation of PNP in the visible light-assisted Fenton-like reaction. Full article

Textile industry effluents contain several hazardous substances, such as dye-containing effluents, which pose environmental and aesthetic challenges. Presently, the microbial-based remediation process is in use. This study investigated the application of ferrous–ferric oxide (Fe₃O₄) nanoparticles, a readily formulated nanoadsorbent, to remove scattered dye molecules from industrial effluents. The ferrous–ferric oxide nanoparticles were prepared using a chemical co-precipitation method. The nanoparticles had 26.93 emu g⁻¹ magnetization, with sizes smaller than 20 nm, and possessed a highly purified cubic spinel crystallite structure. The catalytic activity of the iron oxide depended on the dose, photocatalytic enhancer, i.e., H₂O₂ level, pH of the reaction medium, and dye concentration. We optimized the Fenton-like reaction to work best using 1.0 g/L of ferrous–ferric oxide nanoparticles, 60 mM oxalic acid at pH 7.0, and 60 ppm of dye. Iron oxides act as photocatalysts, and oxalic acid generates electron–hole pairs. Consequently, higher amounts of super-radicals cause the rapid degradation of dye and pseudo-first-order reactions. Liquid chromatography–mass spectrometry (LC-MS) analysis revealed the ferrous–ferric oxide nanoparticles decolorized and destroyed Disperse Red 277 in 180 min under visible light. Hence, complete demineralization is observed using a photo-Fenton-like reaction within 3 h under visible light. These high-capacity, easy-to-separate next-generation adsorption systems are suggested to be suitable for industrial-scale use. Ferrous–ferric oxide nanoparticles with increased adsorption and magnetic properties could be utilized to clean environmental pollution. Full article

Bio-carbon–manganese composites obtained from olive mill wastewater were successfully prepared using manganese acetate as the manganese source and olive wastewater as the carbon precursor. The samples were characterized chemically and texturally by N₂ and CO₂ adsorption at 77 K and 273 K, respectively, by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. Electrochemical characterization was carried out by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The samples were evaluated in the electro-Fenton degradation of tetracycline in a typical three-electrode system under natural conditions of pH and temperature (6.5 and 25 °C). The results show that the catalysts have a high catalytic power capable of degrading tetracycline (about 70%) by a three-electron oxygen reduction pathway in which hydroxyl radicals are generated in situ, thus eliminating the need for two catalysts (ORR and Fenton). Full article

In this study, Fe₃O₄/Ag magnetite-silver (MSx) nanocomposites were investigated as catalysts for advanced oxidation processes by coupling the plasmonic effect of silver nanoparticles and the ferromagnetism of iron oxide species. A surfactant-free co-precipitation synthesis method yielded pure Fe₃O₄ magnetite and four types of MSx nanocomposites. Their characterisation included structural, compositional, morphological and optical analyses, revealing Fe₃O₄ magnetite and Ag silver phases with particle sizes ranging from 15 to 40 nm, increasing with the silver content. The heterostructures with silver reduced magnetite particle aggregation, as confirmed by dynamic light scattering. The UV–Vis spectra showed that the Fe:Ag ratio strongly influenced the absorbance, with a strong absorption band around 400 nm due to the silver phase. The oxidation kinetics of organic pollutants, monitored by in situ luminescence measurements using rhodamine B as a model system, demonstrated the higher performance of the developed catalysts with increasing Ag content. The specific surface area measurements highlighted the importance of active sites in the synergistic catalytic activity of Fe₃O₄/Ag nanocomposites in the photo-Fenton reaction. Finally, the straightforward fabrication of diverse Fe₃O₄/Ag heterostructures combining magnetism and plasmonic effects opens up promising possibilities for heterogeneous catalysis and environmental remediation. Full article

In this paper, carbon-matrix-supported copper (Cu) and cobaltous oxide (CoO) nanoparticles were obtained by using coordination polymers (CPs) as a precursor. The aqueous solutions of copper methacrylate (CuMA) and cobalt methacrylate (CoMA) were preferentially prepared, which were then mixed with anhydrous ethanol to fabricate dual metal ion coordination polymers (CuMA/CoMA). After calcination under an argon atmosphere, the Cu-CoO/C nanocomposite was obtained. Scanning electron microscope (SEM) and transmission electron microscope (TEM) showed that the material has banded morphology, and the dual functional nanoparticles were highly dispersed in the carbon matrix. The prepared material was used in a heterogeneous Fenton-like reaction, with the aim of replacing traditional ferric catalysts to solve pH constraints and the mass production of ferric slime. The obtained nanocomposite showed excellent catalytic performance on the degradation of methylene blue (MB) at near-neutral conditions; the discoloration efficiency is about 98.5% within 50 min in the presence of 0.15 mmol/mL H₂O₂ and 0.5 mg/mL catalyst. And good reusability was verified via eight cycles. The plausible pathway for MB discoloration and the possible catalytic mechanism was also proposed. Full article

A novel Co–Cu composite heterogeneous Fenton-like catalyst was prepared by using a modified hydrothermal method for the degradation of methyl orange solution. The catalyst was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and a Fourier transform infrared spectrometer (FT-IR), which confirmed that the catalyst contained Co(OH)₂, Cu₂O, and an exhibition of a hexagonal crystalline structure with sizes within the range of 0.5–5 μm. The influential factors were researched with the use of univariate analysis and the results showed that: the catalyst has better catalytic properties in the pH range of 2–10 and there was an optimum value of the dosage of the catalyst; the greater the dosage of the catalyst, the faster the COD degradation rate achieves its maximum value; the COD degradation rate increases with a higher reaction temperature. When the pH is 7, the dosage of the catalyst is 0.3 g/L, the dosage of hydrogen peroxide is 50 mL/L, and the reaction temperature is 313 K. The COD degradation rate reached 94% after 50 min of treatment, which proved that the catalyst exhibited high catalysis in a Fenton-like process. Furthermore, reuse of the catalyst and the degradation mechanism of methyl orange were also researched. Full article

MoS₂ has garnered considerable attention as an exceptional co-catalyst that is capable of significantly enhancing the efficiency of H₂O₂ decomposition in advanced oxidation processes (AOPs). This improvement allows for a reduction in the required amounts of H₂O₂ and Fe²⁺. In this study, we investigated the cyclic durability of photo-Fenton catalysts, focusing on the degradation of pollutants through the introduction of PPy into heterogeneous 1T-2H MoS₂ units. The resulting photothermal-Fenton catalysts, comprising non-ferrous Fenton catalysts, demonstrated excellent degradation performance for simulated pollutants. In comparison with 1T-2H MoS₂, the PPy@1T-2H MoS₂ composite exhibited remarkable stability and photothermal enhancement in the photo-Fenton degradation of methylene blue (MB) under visible light irradiation. The photo-Fenton reaction efficiently degraded contaminants, achieving 99% removal within 5 min and 99.8% removal within 30 min. Moreover, the co-catalyst complex displayed enhanced cyclic stability during the photo-Fenton reaction, with a contaminant removal efficiency of 92%, even after the 13th cyclic test. The combined effects of PPy and 1T-2H MoS₂ demonstrated improved efficiency in both photocatalytic and photo-Fenton catalytic reactions. Furthermore, PPy@1T-2H MoS₂ exhibited outstanding performance in the photothermal evaporation of water, achieving an efficiency of 86.3% under one solar irradiation. Full article

Dps proteins (DNA-binding proteins from starved cells) are multifunctional stress defense proteins from the Ferritin family expressed in Prokarya during starvation and/or acute oxidative stress. Besides shielding bacterial DNA through binding and condensation, Dps proteins protect the cell from reactive oxygen species by oxidizing and storing ferrous ions within their cavity, using either hydrogen peroxide or molecular oxygen as the co-substrate, thus reducing the toxic effects of Fenton reactions. Interestingly, the interaction between Dps and transition metals (other than iron) is a known but relatively uncharacterized phenomenon. The impact of non-iron metals on the structure and function of Dps proteins is a current topic of research. This work focuses on the interaction between the Dps from Marinobacter nauticus (a marine facultative anaerobe bacterium capable of degrading petroleum hydrocarbons) and the cupric ion (Cu²⁺), one of the transition metals of greater biological relevance. Results obtained using electron paramagnetic resonance (EPR), Mössbauer and UV/Visible spectroscopies revealed that Cu²⁺ ions bind to specific binding sites in Dps, exerting a rate-enhancing effect on the ferroxidation reaction in the presence of molecular oxygen and directly oxidizing ferrous ions when no other co-substrate is present, in a yet uncharacterized redox reaction. This prompts additional research on the catalytic properties of Dps proteins. Full article