Fenton-like Process Research Articles

Using SiO2-Supported MnO2@Fe2O3 Composite to Catalytically Decompose Waste Drilling Fluids Through Fenton-like Oxidation

Waste drilling fluids produced from oil extraction can cause serious harm to the ecological environment; thus, the treatment of waste drilling fluids is urgent and important to ensure the sustainability and development of the oil extraction. In this work, we used the Fenton-like reaction method to degrade waste drilling fluids with SiO2-supported MnO2@Fe2O3 composite material as a catalyst in the presence of H2O2. During the Fenton-like reaction process, the MnO2@Fe2O3 interface exhibits exceptional activity by facilitating the production of ·OH species with high activity and strong oxidizing properties, which degrade the organic substances in the waste drilling fluids into smaller inorganic molecules, thereby reducing its COD value. Compared to the reaction only with H2O2, after reacting with sufficient SiO2-supported MnO2@Fe2O3 catalyst for 4 h at 60 °C in the presence of H2O2, the COD value of the waste drilling fluids is reduced by 36,495 mg L−1, a decrease of more than 95%. This performance is significantly superior to that of the traditional Fenton reagent FeSO4, which reduced the COD by 32,285 mg L−1, a decrease of 84%. This work provides an important composite catalyst, which is practically useful for the treatment of waste drilling fluids.

Ultrasound-assisted bisphenol AF degradation using in situ generated hydrogen peroxide

Bisphenol AF (BPAF) is degraded through the ultrasound-assisted in situ generation and activation of hydrogen peroxide (H2O2) by the copper(II) catalysed oxidation of hydroxylamine (NH2OH) with dioxygen (O2). Compared to added H2O2, in situ generated H2O2 significantly improves the degradation of BPAF from 46.7% to 94.8% in ∼15 min. The reaction follows a pseudo-first-order kinetic model. This study examines the influence of solution pH, anions, humic acid, and different concentrations of the reactants on BPAF degradation. Mass spectrometry was used to identify the BPAF degradation products, and a degradation pathway is proposed. This work advances the understanding of in situ hydrogen peroxide generation and activation in advanced oxidation (Fenton-like) processes (AOPs).

Polypyrrole-bound carbon nanotube conductive polysulfone membranes for self-cleaning of fouling

A novel conductive membrane, polypyrrole carbon nanotubes polysulfone (PPy-CNT-PSF), was successfully synthesized using the membrane phase infiltration in-situ polymerization method (MPIP). The resulting PPy-CNT-PSF, utilized as an anode in the electrochemical filtration reactor, exhibited a chain-like morphology of PPy extending from within to the exterior of the PSF membrane, effectively anchoring the CNT layer on its surface and establishing a stable conductive network with a surface resistance of 0.142 ± 0.052 kΩ/cm. Its electrical conductivity surpasses that of most conductive membranes derived from pyrrole (Py). Furthermore, the structural integrity of this conductive membrane remained intact following exposure to chlorine. Cyclic voltammetry (CV) analysis revealed a subtle redox peak with no significant alteration in surface structure after 50 CV cycles. This reaction can be attributed to a Fenton-like reaction process due to Fe presence detected by EDX on the surface. Current-time curves under constant potential further confirmed that the PPy-CNT-PSF conductive membrane possesses both a stable conductive network and favorable electrode stability. Additionally, self-cleaning occurred when voltage was applied during electrochemical experiments utilizing a conductive membrane anode paired with a Ti cathode due to electrostatic repulsive forces. At an applied voltage of 20 V, removal efficiency and flux restoration achieved values of 97.63 % and 100 %, respectively. This straightforward yet effective approach is believed to hold promise for fabricating conductive membranes characterized by structural stability and electrode reliability for practical applications aimed at mitigating membrane fouling.

Synthesis of Fe3O4 Derived from Acid Mine Drainage (AMD) Sludge and Catalytic Degradation of Tetracycline.

Acid mine drainage (AMD) sludge is waste generated in the process of acid mine wastewater treatment, and the use of AMD sludge to prepare Fe3O4 to activate H2O2 degradation pollutants is an effective means of resource utilization. In this study, the heterogeneous catalyst Fe3O4-based composites were synthesized by a one-step method using AMD sludge as a raw material, and the Fe3O4-based materials before and after catalysis were characterized by powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The effects of several key factors (pH values, H2O2 content, TC concentration, and Fe3O4 content) of tetracycline (TC) degradation were evaluated. The results revealed that the TC removal rate reached up to 95% within 120 min under optimal conditions (pH 3; H2O2, 5 mmol/L; TC concentration, 25 mg/L; Fe3O4 content, 1g/L). Moreover, •OH and •O2- radicals were generated during the Fenton-like degradation process, and the plausible degradation mechanism was discussed. Besides, the Fe3O4 catalyst exhibited fantastic stability after five cycles. In conclusion, this study is expected to promote the resource utilization of industrial sludge and provide a new material for the treatment of antibiotic-contaminated wastewater.

Utilization of waste citrus limetta peel for the green synthesis of iron catalyst and its subsequent application in fluidized-bed Fenton-like process for environmental sustainable treatment of organic pollutant

This work focuses on the environmental friendly synthesis of an iron-based catalyst utilizing extract from waste citrus limetta peels. The main objective is to encourage the sustainable use of bio-waste materials in catalytic processes. This innovative method demonstrates the efficacy of bio-derived materials in catalysis by removing the need for hazardous chemicals. The green-synthesized catalyst was analyzed using many characterization methods, including X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). These analyzed results give insightful information on the physicochemical properties of green-synthesized catalysts. Furthermore, the prepared catalyst was utilized in a fluidized-bed reactor to facilitate the Fenton degradation of dye effluent, with a specific focus on the commonly used Eosin yellow (EY) dye. The iron catalyst derived from plant-based waste material accomplished an impressive 98% degradation of EY within a 90-minute time frame under optimized working conditions, using a minimal quantity of catalyst. An in-depth analysis was conducted to study the kinetics and process mass transfer in order to improve the comprehension of catalytic processes occurring in the fluidized-bed reactor. The Fenton decomposition of dye effluent is likely to be explained by first-order reaction kinetics. Additionally, confirmed enhanced catalytic durability and decreased deactivation of surface sites of the prepared catalyst after three consecutive oxidation cycles. These findings underscore the potential of this approach in sustainable wastewater treatment, highlighting both its efficiency and cost-effectiveness.

Revealing the essence of anion ligands in regulating amorphous MnOx to activate peracetic acid for micropollutant removal

How the anion ligands of manganese precursors affect the catalytic activity of amorphous manganese oxides (MnOx) in Fenton-like process is poorly understood. Here, five amorphous MnOx synthesized by Mn(II) precursors with different ligands were characterized and adopted to activate peracetic acid (PAA) for bisphenol A (BPA) degradation. Although > 90 % BPA removal was achieved in the five MnOx/PAA processes via both adsorption and oxidation, the oxidation kobs greatly differentiates by the ligands types with the order of MnOx-N > MnOx-S > MnOx-Cl > MnOx-AA > MnOx-OA. Ligands types would affect the specific surface area of MnOx and their ability to adsorb BPA, however which is not the decisive factor in determining the contaminant oxidation efficiency. Multiple experimental results indicate that the generation of oxygen vacancies induced by the ligands alters the Mn(III)/Mn(IV) ratio, ultimately contributing to the different efficiency of BPA oxidation driven by the direct electron transfer mechanism. Moreover, amorphous MnOx holds the promise of practical applications in catalytic PAA of various micropollutants with good stability. This study advances the fundamental understanding of ligand-regulated amorphous MnOx-catalyzed PAA process.

Synergistic enhancement in hydrodynamic cavitation combined with peroxymonosulfate fenton-like process for bpa degradation: New insights into the role of cavitation bubbles in regulation reaction pathway

The combination of hydrodynamic cavitation (HC) and Fenton-like oxidation technology can dramatically enhance the pollutant removal capacity, however, the synergistic effect of cavitation and catalysts on reactive oxygen species (ROS) generation remained enigmatic. In this study, we established a combined system based on HC and Ce-MnFe2O4 activated peroxymonosulfate (PMS) for BPA removal, and attentions were paid on the role of cavitation bubbles. The results show that the combination of HC in Ce-MnFe2O4 activated PMS could mediate the degradation of BPA from the non-radical pathway dominated by 1O2 to •O2− dominated radical pathway. Both controlled experiments and theoretical calculations revealed that the cavitation bubbles with different sizes play the dominant role in ROS generation. The microjets produced by the collapse of cavitation bubbles could create a large number of oxygen vacancy defects on Ce-MnFe2O4 surface, which modify the activation barrier of PMS and facilitate the generation of •O2− thermodynamically. The stable existing cavitation bubbles with the size of 100∼400 nm could create considerable gas-liquid interface. The molecular dynamics simulations show that the nano bubbles can concentrate the BPA and increase the probability of contacts between BPA and Ce-MnFe2O4, hence effectively solve the issues of short lifetime of •O2− radicals and limited mass transfer distance to strengthen the reaction. In addition, the PMS/Ce-MnFe2O4/HC system not only achieves the satisfied COD (95 %) and TOC (65 %) removal efficiency but also enabled the BPA-contaminated water with a low energy cost of 0.065 kWh·m−3 and oxidant cost, highlighting the application potential of the HC technology for contaminated water.

Cu-Co binary metal-organic framework nanosheets for highly efficient degradation of norfloxacin using the Fenton-like process

Efficient catalyst development for hydrogen peroxide activation is crucial in advanced oxidation processes (AOPs) technology. In this study, we successfully synthesized a bimetallic organic framework incorporating Cu-Co MOF nanosheets via a one-pot strategy. The subsequent Cu-Co MOF nanosheets demonstrated outstanding oxidative activity, achieving a remarkable 95.37 % removal of norfloxacin (NOR), surpassing the efficacy of Cu MOF/H2O2 or Co MOF/H2O2 nanosheets alone by 1.34 and 2.59 times, respectively. Density functional theory (DFT) calculations revealed that the bimetallic MOF nanosheets: firstly, enhanced optimization of the adsorption energy for H2O2 activation; and secondly, facilitated the cleavage of the O–O bond in H2O2. Furthermore, electrochemical impedance spectroscopy (EIS) analysis demonstrated a significant improvement in interfacial electron transfer once dual-reaction centers were introduced into the Cu-Co MOF nanosheets. Electron paramagnetic resonance analysis and quenching tests confirmed that 1O2, ·O2− and ·OH were involved in NOR degradation. Reasonable NOR degradation pathways were proposed by analysing the results of LC-MS and DFT calculations. Moreover, the synthesized nanosheets exhibited excellent reusability, with more than 90.00 % NOR removal achieved using the Cu-Co MOF nanosheets/H2O2 system after reuse on 3 occasions. These findings underscore the effectiveness of bimetallic MOF construction in developing highly efficient MOF-based Fenton-like catalysts. Also highlighted here is the promising role of Cu-Co MOF nanosheets in wastewater treatment, particularly for the removal of antibiotics.

Elimination of malachite green by modified Fenton like process. Application of Box Behnken design

<p style="line-height:200%;text-align:justify;"><span style="line-height:200%;" lang="EN-US">The aim of this work was to investigate an advanced oxidation process for removing malachite green from aqueous solutions using a modified Fenton-like process. An experimental Box-Behnken design was applied to determine the optimal conditions by examining the effects of catalyst concentration ([Fe<sup>2+</sup>]), oxidant concentration ([K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>]), and stirring speed. The analysis of variance (ANOVA) indicated that oxidant concentration was the most significant factor, with a p-value of 0.001, while catalyst concentration, the quadratic term of the oxidant, and the interaction between catalyst concentration and stirring speed were also significant. The optimal conditions for maximum dye removal were found to be a catalyst concentration of 3.5 ppm, an oxidant concentration of 3.07 ppm, and a stirring speed of 200 rpm, achieving a theoretical degradation yield of 100% and an experimental yield of 98%. This agreement validates the model and the importance of the optimized parameters. Additionally, degradation kinetics studies in various natural waters revealed that oxidation efficiency followed this order: Distilled water (98%) > Seawater ≈ Industrial water (88.97%) > Source water (85.57%) > Mineral water (80.52%).</span></p>

Localized heating coupling with radical oxidation eliminating antibiotic resistance genes (ARGs) in interfacial photothermal Fenton-like disinfection process

Conventional oxidative disinfection processes are inefficient in eliminating intracellular antibiotic resistance genes (iARGs) due to the barrier of the cell membrane and the competitive reaction of cellular constituents within antibiotic-resistant bacteria (ARB), resulting in the widespread prevalence of ARGs in recycled water. This study presented the first application of localized heating coupling with advanced oxidation to destroy the resistant Escherichia coli cells and improved subsequent iARGs (blaTEM-1) degradation in a novel photothermal Fenton-like disinfection process. The Fe-Mn@CNT microfiltration membrane, comprising carbon nanotubes wrapped with Fe and Mn nanoparticles (Fe-Mn@CNT), was employed as a nanomaterial for photothermal conversion and H2O2 activation. The highly efficient absorption of full-spectrum photons by CNTs enabled the Fe-Mn@CNT membrane to concentrate light to generate localized intense heat, resulting in the destruction of ARB nearby, and the subsequent release of iARGs. Interfacial heat favored Fe-Mn-induced H2O2 activation, leading to the production of more ·OH, which in turn promoted the oxidation for ARG degradation and ARB cell damage. The results of the acetylcysteine quenching experiments indicated that interfacial heating and radical oxidation-induced accumulation of intracellular reactive oxygen species contributed to the elimination of about 1-log iARGs through direct attack. The integrity of the cell membrane, the morphology of ARB and the variation of i/e ARG copy numbers were observed to reveal that the introduction of interfacial heating aggravated the cell lysis and accelerated the iARGs release, resulting in the inactivation of 7.27-log ARB and the elimination of 4.64-log iARGs and 2.23-log eARGs. Localized heating coupling with ·OH oxidation achieved a 143 % increase in iARGs removal compared to the conventional Fenton-like oxidation. The interfacial photothermal Fenton-like disinfection process exhibited remarkable material stability, robust disinfection performance, and effective suppression of horizontal gene transfer, underscoring its immense potential to mitigate the risk of ARG dissemination in reclaimed water systems.

Photocatalytic Fenton-like degradation of Acid Green 25 by novel aluminum nanoferrites with persulfate: Optimization by response surface methodology

Magnetic nanomaterials are gaining increasing attention for their catalytic properties and ease of recovery, making them promising candidates for the degradation of various organic pollutants. In this study, AlFe2O4 nanoparticles were employed for the first time in photocatalytic wastewater treatment. The study focused on removing Acid Green 25 anthraquinone dye through persulfate activation under UV-Visible light. AlFe2O4 nanoparticles were synthesized via sol-gel auto-combustion method and characterized by various techniques (XRD, SEM, EDX, VSM, Raman and FTIR). Moreover, statistical analysis of the experimental data confirmed the strong performance of the RSM model in accurately representing the photocatalytic process. Under optimal conditions including persulfate and catalyst concentrations of 0.3 g/L and 0.83 g/L respectively, a solution pH of 3 and 45 minutes of contact time, a 96 % dye removal rate was achieved. The remaining persulfate concentration was 60 % and fully depleted within 90 minutes, indicating efficient activation by AlFe2O4 photocatalyst. The activation process effectively suppressed electron-hole recombination, enhancing the overall efficiency. Scavenger experiments further identified surface-bound radicals and photogenerated holes as the main reactive species. A degradation mechanism for AG25 dye via a photocatalytic Fenton-like process was proposed, highlighting dual synergistic catalysis in the dye degradation. Ecotoxicity assessments using Vibrio fischeri bioassay revealed a significant reduction in toxicity after treatment with AlFe2O4/PS/UV-Vis system. The stability of AlFe2O4 was demonstrated over five degradation cycles. The findings open new perspectives for the use of AlFe2O4 in advanced wastewater treatment technologies, positioning it as a promising material for the degradation of persistent pollutants.

Degradation of Nile Blue by Photocatalytic, Ultrasonic, Fenton, and Fenton-like Oxidation Processes

The aim of this study is to investigate new catalytic systems for the degradation of a dye that has been classified as first-degree toxic pollutant. Advanced oxidation process such as photocatalytic oxidation, ultrasonic oxidation, Fenton, and Fenton-like constitute a promising technology for the treatment of wastewater containing organic compounds. Waste effluents from textile industries are a major source of water pollution. These wastewaters contain dyes, which have high toxicity and low biodegradability. In this study, degradation of Nile Blue (NB), an azo dye, was studied using the photocatalytic oxidation (TiO2 and silver-loaded TiO2 (Ag-TiO2) as catalyst), ultrasonic oxidation, Fenton (Fe(II)/H2O2), and Fenton-like (Cu(II)/H2O2, V(IV)/H2O2) processes. It was found that the photocatalytic degradation of NB increased with decreasing pH, and the degradation rate also increased in the presence of TiO2/UV compared to UV irradiation alone. In addition, Ag loading on TiO2 dramatically reduced the degradation time. The ultrasonic degradation of NB was also studied using different initial dye concentrations at different pH values and amplitudes. Concentrations of Fe(II), Cu(II), V(IV) and H2O2 on degradation ratio were investigated. It is found that Fe(II) ion is more effective than Cu(II) and V(IV) ions in the degradation of NB.

Mechanism of o-cresol polymerization and its carbon recovery from aqueous solution by a cathode/Fe2+/H2O2 process

Converting organic pollutants into easily recyclable solid polymers has the advantages of saving oxidants and recovering organic carbon, compared to degrading them into smaller organic molecules. Taking o-cresol as a representative phenolic pollutant, this study realizes the dominant reaction of organic polymerization and the recovery of organic carbon from wastewater via a cathode/Fe2+/H2O2 process. With HO• initiation, 53 % of chemical oxygen demand is removed in the form of suspended solid polymers and equivalent organic carbon is recovered. At the same time, the dissolved organic carbon (DOC) removal reaches 64 %, and the H2O2 consumption is only a quarter of that in an ideal degradation process. The recovered solid polymers are oligomers derived from o-cresol and its derivatives, with the molecular weight ranging from 400 to 2500 Da. The polymerization pathway involves repeated HO• oxidation and coupling of intermediate organic radicals. The energy consumption is 26.7 kWh/kg DOC, significantly lower than that of previous Fenton-like processes in the literature. This study broadens the scope of polymerization-based technologies for organic wastewater treatment, and demonstrates that HO• has the potential to simultaneously reduce organic pollution and recover organic carbon by generating suspended solid organic polymers, which may provide new avenues for H2O2-based Fenton processes toward resource recovery and water purification.

Flotation separation of ilmenite and titanaugite modified by Fe2+-assisted peroxymonosulfate oxidation: Performance and activation mechanism

Efficient separation of ilmenite and titanaugite has always been recognized challenge in modern mineral processing. The use of a heterogeneous Fenton-like oxidation process composed of peroxymonosulfate (PMS) and Fe2+ is promising to address this issue. Flotation findings indicated that effective recovery of ilmenite could be achieved under weak acidic conditions, and a TiO2 recovery of 81.56 % and a grade of 32.16 % concentrate was collected. A series of characterization analyses confirmed that the PMS-Fe2+-mediated Fenton-like reaction in the ilmenite system generated more •OH and SO4•- radicals, which oxidized Fe2+ to Fe3+ on its surface, thus improving the active sites on ilmenite surface. Moreover, PMS-Fe2+ promoted the positive shift of surface charge on ilmenite, facilitating NaOL adsorption and making the surface more hydrophobic. NaOL primarily interacted with Fe active sites on the ilmenite surface and Mg2+ and Ca2+ active sites on the titanaugite surface in the formation as chemisorption. Thus, PMS-Fe2+ activated ilmenite mainly via augmenting the quantity and reactivity of Fe active sites on the surface. In summary, these findings provide the innovative pathways to implement the advanced oxidation processes in mineral flotation.

Degradation of tetracycline in water using hydrogen peroxide activated by soybean residue-derived magnetic biochar

Tetracyclines (TCs) are the second most commonly used antibiotics worldwide, utilized both in medical treatments and animal husbandry. Although effective against various infectious diseases, TC residues persist in the environment and contribute to the emergence of antibiotic-resistant pathogens, posing significant risks to human health. This study employed the heterogeneous Fenton process to degrade TC using soybean residue-derived magnetic biochar (Fe-SoyB) as the catalyst. The Fe-SoyB sample was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and superconducting quantum interference device (SQUID) techniques. The effects of key parameters, including pH, H2O2 concentration, catalyst dosage, and initial TC concentration, on TC degradation were investigated. The results indicated that the TC removal efficiency decreased with increasing initial TC concentration, while it was improved with higher H2O2 concentrations and greater catalyst dosages. The optimal conditions for the Fenton-like process were determined to a pH of 3, a H2O2 concentration of 245 mmol/L, an initial TC concentration of 800 mg/L, and a catalyst dosage of 0.75 g/L, achieving a removal efficiency of 90% after 150 min. Additionally, the TC removal efficiency of the Fe-SoyB system varied significantly across different water matrices, with 87.1% for deionized water, 78.5% for tap water, and 72.5% for river water. The catalyst demonstrated notable stability, maintaining a TC removal efficiency of 79.7% after three cycles of use. Overall, Fe-SoyB shows promise as a cost-effective catalyst for the elimination of organic pollutants in aqueous solutions.

The catalytic pathways on niobium-cerium loading catalysts for methylene blue elimination in the Fenton-like system: Roles of oxygen vacancies

The oxidation pathways affected by asymmetric and symmetric Ov sites on catalysts in the Fenton-like process should be illustrated in detail. Based on the experimental and theoretical results, it can be revealed that the asymmetric Ov sites favored nonradical species (1O2) formation by triggering H2O2 and DO to produce surface O2·-, and the migration distance between the species and pollutant was shortened due to the excellent adsorption of methylene blue (MB) on the sites. OH species were liable to be generated on the symmetric Ov sites. Calcination and the amount of medium strong acid sites of the support may be important roles in the formation of asymmetric Ovs for the Nb-Ce loading catalyst prepared by impregnation. This work unravels the different catalytc pathways of asymmetric and symmetric Ovs dominated, and also provides a facile strategy to control the oxidation pathway as desirable in the H2O2-Fenton-like system.

Bio-templated micromotors for simultaneous adsorption and degradation of microplastics

Microplastic contamination has increasingly become a focus of public attention due to its ubiquity on earth. As the appearance of microplastics in the human body has raised great concerns about their effects on human health, it is imperative to develop efficient technologies to remove microplastics. In this work, taking advantage of the hollow structure of kapok fibers and low-cost MnO2 catalyst, a tubular self-driven micromotor was synthesized for simultaneous adsorption and degradation of microplastics. Functionalization with polydopamine endowed the micromotors with the ability of on-the-fly capture of microplastics. Attributed to the enhanced diffusion caused by the self-propulsion, the propelled micromotors exhibited an adsorption efficiency 3.41 times that of static micromotors, achieving a removal ratio of 73.57 % in 1 mg/mL polystyrene microspheres dispersion in 30 min without external stirring, which poses a prospective approach for in-situ removal of microplastics. In addition, coupling with photocatalytic CdS, the formed CdS/PDA heterojunction could generate photo-induced charge carriers, which together with the active species produced through the Fenton-like processes contributed to the degradation of microplastics. This work proposed a new platform for the simultaneous adsorption and degradation of microplastics and may provide implications for the removal of microplastics in the environment.

Bimetallic-organic framework (Fe, Cu)/carbon nanotubes encapsulated Ni nanoparticles as heterogeneous catalyst in Fenton-like process for degradation of acid orange 7 dye

Bimetallic-organic framework (Fe, Cu)/carbon nanotubes encapsulated Ni nanoparticles as heterogeneous catalyst in Fenton-like process for degradation of acid orange 7 dye

Synergistic photocatalysis and fenton-like process driven by a biochar-supported biochar/iron hydroxide oxide/bismuth molybdate S-type heterojunction for tetracycline degradation: Mechanistic insights and degradation pathways

Photocatalysis-Fenton system, based on S-type iron hydroxide oxide/bismuth molybdate supported on biochar, was fabricated for efficient tetracycline removal. Biochar/iron hydroxide oxide/bismuth molybdate catalyst not only exhibits exceptional photocatalytic performance but also accelerates the Fenton reaction cycle in the presence of hydrogen peroxide. Within 40 min, the biochar/iron hydroxide oxide/bismuth molybdate achieved a remarkable degradation efficiency of 97% for tetracycline, surpassing that of biochar/iron hydroxide oxide (65%) and biochar/bismuth molybdate (59%). Experimental analysis and density functional theory calculations confirmed the charge migration mechanism of S-type iron hydroxide oxide/bismuth molybdate. Moreover, the excellent degradation ability of biochar/iron hydroxide oxide/bismuth molybdate was demonstrated across a wide pH range (3–11), overcoming the limitations associated with traditional Fenton systems that operate efficiently only within a narrow pH range. Quenching experiments and electron paramagnetic resonance tests identified primary active species including •O2–, h+, and •OH. Additionally, we elucidated the potential degradation pathway of tetracycline in this study, supplying novel perceptions into synthesizing bifunctional photocatalysts in photocatalysis-Fenton-like systems.

Efficient degradation of methylene blue at near neutral pH based on heterogeneous Fenton-like system catalyzed by Fe2O3/MnO2

The contamination of aquatic environments by organic dye contaminants in industrial wastewater has attracted widespread global attention. The heterogeneous Fenton-like process presents an attractive method for degrading dye pollutants, especially when such reactions are conducted under neutral pH. In this study, Fe2O3/MnO2 composite was employed as a novel heterogeneous catalyst for activating hydrogen peroxide (H2O2) to oxidize and subsequently degrade methylene blue (MB) under neutral pH. Multiple characterization results have confirmed the presence of MnO2 and Fe2O3 as the primary phases of the synthesized compound catalyst. Degradation experiments have demonstrated that the degradation efficiency of MB approaches 100% under the conditions of H2O2 concentration of 0.30% and Fe2O3/MnO2 amount of 0.888 g/L. Furthermore, the Fe2O3/MnO2 catalyst exhibits consistent and outstanding catalytic activity within a broad pH range from 5 to 9 benefiting from the strong interface interaction in Fe2O3/MnO2. The investigation into the kinetics of the Fenton-like reaction indicates that the catalytic degradation of MB by Fe2O3/MnO2 in conjunction with H2O2 follows pseudo-first-order kinetics. Moreover, supplementary scavenging experiments have demonstrated the crucial role played by hydroxyl radicals (·OH) in the catalytic oxidation mechanism of MB. This study offers a promising catalyst for the treatment of dye-containing wastewater under neutral pH condition.