Search Results (83)

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

Sulfamethazine (SMT) is an antibiotic with good antimicrobial effect and is widely used to treat human and livestock diseases. Though the degradation of SMT by the conventional Fenton and electro-Fenton (EF) processes is efficient, it is limited by a narrow pH and iron sludge generation. Herein, we constructed a cost-effective EF system with the synergistic effect of zero-valent iron (Fe⁰) and sulfite (Fe⁰-EF/Sulfite), and key parameters such as applied current, catalyst dosing, sulfite dosage, and initial pH were optimized. Under the optimal conditions (Fe⁰ dosing of 50 mg/L, sulfite dosage of 1.5 mM, current of 40 mA, and pH of 3), the removal efficiency of 10 mg/L SMT reached 100% within 30 min, and the degradation rate constant reached 0.194 min⁻¹. Electron paramagnetic resonance (EPR) analysis and quenching experiments confirmed the generation of various reactive oxygen species (ROS), such as ^•OH, SO₄⁻, O₂⁻, and ¹O₂, which significantly improved the pollutant removal efficiency. Sulfite accelerated iron cycling and inhibited the formation of iron sludge, thus broadening the pH range of the reaction from three to eight and overcoming the limitations of the conventional EF process. The Fe⁰-EF/Sulfite system performs cost-effectively at a wide pH range, providing an efficient and low-carbon solution for environmental pollution remediation with broad application prospects. Full article

This article provides an overview of the use of electrochemical advanced oxidation processes (EAOPs) applied to the treatment of water contaminated by pesticides. Given the global increase in the use of pesticides and the ineffectiveness of conventional treatment methods, EAOPs emerge as promising alternatives. They stand out for their efficiency in the degradation of organic compounds, minimal reliance on additional chemical reagents, and minimal generation of waste. The main methods addressed include anodic oxidation, photoelectro-oxidation, electro-Fenton and photoelectro-Fenton, which use hydroxyl radicals, a potent non-selective oxidant, to mineralize pollutants. A total of 165 studies were reviewed, with emphasis on the contributions of countries such as China, Spain, Brazil, and India. Factors such as electrode type, presence of catalysts, pH, and current density influence the effectiveness of treatments. Combined processes, especially those integrating UV light and renewable sources, have proven to be more efficient. Despite challenges related to electrode cost and durability, recent advances highlight the sustainability and scalability of EAOPs for the treatment of agricultural and industrial effluents contaminated with pesticides. Full article

Steroid hormones are micropollutants that contaminate water worldwide and have significant impacts on human health and the environment, even at very low concentrations. The aim of this article is to provide an overview of technologies for the removal of endocrine-disrupting compounds with a focus on oestrogens (estrone E1, 17β-oestradiol E2, estriol E3), the synthetic oestrogen (17α-ethinylestradiol EE2 and bisphenol A BPA), and pharmaceuticals found in wastewater. Hormonal and pharmaceutical contaminants are mostly persistent organic compounds that cannot be easily removed using conventional wastewater treatment processes. For this reason, researchers have tried to develop more efficient tertiary wastewater treatment technologies to reduce micropollutant concentrations in wastewater. This review covers the following processes: Advanced oxidation, nanofiltration, ultrasound, electro-Fenton processes, electrolysis, adsorption, ozonation, photolysis, photocatalysis, ultrafiltration, and electrocoagulation. Attention was paid to the effectiveness of the processes in terms of eliminating hormones and pharmaceuticals from wastewater, as well as on economic and environmental aspects. The combination of different processes can be a promising treatment scheme for retaining and degrading hormonal and pharmaceutical compounds from wastewater. With hybrid technologies, the advantages of the methods are combined to maximise the removal of pollutants. However, optimal methods of wastewater treatment depend on the quality and quantity of the wastewater, as well as the residual hormonal and pharmaceutical compounds and their hazardous effects. Full article

Heterogeneous electro-Fenton (HEF) technology utilizing iron-based cathode catalysts has emerged as an efficient advanced oxidation process for wastewater treatment, demonstrating outstanding performance in degrading emerging organic contaminants (EOCs) while maintaining environmental sustainability. The performance of this technology is governed by two critical processes: the accumulation of H₂O₂ and the electron transfer mechanisms governing the Fe(III)/Fe(II) redox cycle. This review comprehensively summarizes recent advances in understanding the electron transfer mechanisms in iron-based HEF systems and their applications for EOC degradation. Five representative catalyst categories are critically analyzed, including zero-valent iron/alloys, iron oxides, iron-carbon/nitrogen-doped carbon composites, iron sulfides/phosphides, and iron-based MOFs, with a particular focus on their structural design, catalytic performance, and electron transfer mechanisms. A particular focus is placed on strategies enhancing Fe(III)/Fe(II) cycling efficiency and the interplay between radical (^•OH) and non-radical (¹O₂) oxidation pathways, including their synergistic effects in complex wastewater systems. Major challenges, including catalyst stability, pH adaptability, and selective oxidation in complex matrices, are further discussed. Potential solutions to these limitations are also discussed. This review provides fundamental insights for designing high-efficiency iron-based HEF catalysts and outlines future research directions to advance practical applications. Full article

Industrial organic wastewater, with its complex composition, high biological toxicity, and recalcitrance, has become a major challenge in water pollution control. This is especially true for antibiotic-containing wastewater, such as ofloxacin wastewater, for which there is an urgent need to develop effective treatment technologies. Conventional treatment processes are insufficiently efficient, while individual advanced oxidation processes (AOPs) have drawbacks such as poor oxidation selectivity and catalyst deactivation. To address these issues, researchers have explored the coupling of different AOPs and found that such combinations can enhance the oxidation performance, achieve complementary advantages, reduce the equipment costs, and offer great development potential. An experiment was conducted to evaluate the performance of an Ozone-Electro-Fenton coupled process in treating ofloxacin industrial wastewater. The results demonstrated that under the same conditions, after four hours of treatment, the coupled process achieved a 70% reduction in the UV absorption peak of the wastewater, compared to less than 20% for individual processes, indicating a significant synergistic effect. Further optimization of the ozone aeration structure revealed that with a hole size of 0.5 mm, single-layer aeration holes, and six holes, the COD removal rate reached 96% after six hours, the ozone utilization improved to 85%, and the gas holdup stabilized at 4.6%. Under these conditions, the mixture of ozone and air bubbles formed mixed bubbles. Influenced by the electric field and electrode plate wall effects, the bubble residence time was prolonged. The bubble size was approximately 2.8 mm, the gas flow horizontal velocity was about 18.5 m/s, and after a horizontal displacement of 0.17 mm in the wastewater, the lateral velocity became zero. The ratio of the distance between the bubble center and the wall to the equivalent bubble diameter was approximately 3.45. The bubbles were subject to a strong wall effect, which extended their residence time. This not only facilitated the removal of small bubbles from the electrode plates but also enhanced the ion diffusion near the plates, thereby boosting pollutant degradation. This study shows that the Ozone-Electro-Fenton coupled process is highly effective in degrading ofloxacin industrial wastewater, offering an innovative solution for treating other antibiotic-containing wastewater. Future research will focus on further optimizing the process, improving its adaptability to complex matrix wastewater, and validating it at the pilot scale to promote its engineering application. Full article

Electrochemical-based processes have shown great promise in removing organic pollutants such as non-steroidal anti-inflammatory drugs (NSAIDs) from wastewater due to their effectiveness in addressing environmental pollution. This study conducts a bibliometric analysis of the most-cited articles in the field to systematically evaluate the progress and current state of electrochemical methods for NSAID removal from wastewater. Additionally, it highlights the potential of combining electrochemical techniques with other treatment methods to enhance the overall efficiency of NSAID removal. Research in this field has mainly focused on three technologies: electro-peroxone process (E-peroxone), electro-Fenton (EF), and electrochemical oxidation (EO). Early studies prioritized EO-based treatments, but interest has gradually shifted toward EF and E-peroxone. Future research is expected to focus on the development of cost-effective electrode materials, improving energy efficiency, and exploring hybrid systems for more effective treatment of wastewater contaminated with NSAIDs. An integrated bibliometric and systematic review framework presented in this study provides the first comprehensive assessment of electrochemical strategies for NSAIDs removal, highlighting the evolution of research focus and the potential of hybrid approaches. Full article

Polyethylene microplastics (PE MPs) pose a severe threat to aquatic ecosystems and human health, demanding urgent, sustainable remediation strategies. While the electro-Fenton process is widely used for treating refractory pollutants in wastewater, its standalone application remains inadequate for PE MPs due to their stable chemical structure and complex molecular chains. This study introduces a green and sustainable magnetite-activated persulfate electro-Fenton (Mt-PS-EF) system designed to address these limitations while aligning with circular-economy principles. By synergizing Fe₃O₄ catalysis, persulfate activation, and electrochemical processes, the Mt-PS-EF system achieves efficient PE MP degradation through hydroxyl (·OH) and sulfate (SO₄·⁻) radical-driven oxidation. Under optimized conditions (60 mg/L PE, 40 mM persulfate, 150 mg Fe₃O₄, 20 h treatment), a 90.6% degradation rate was attained, with PE MPs undergoing chain scission, surface erosion, and release of low-molecular-weight organics. Crucially, the magnetic property of magnetite facilitated the recovery and reuse of the catalyst, significantly reducing material costs and minimizing waste generation. By integrating catalytic efficiency with resource recovery, this work advances scalable, eco-friendly solutions for microplastic pollution mitigation, directly contributing to UN Sustainable Development Goals (SDGs) 6 (Clean Water) and 14 (Life Below Water). The findings highlight the potential of hybrid electro-Fenton technologies in achieving sustainable wastewater treatment and plastic waste management. Full article

Contamination of water resources, particularly from industrial discharges, agricultural runoff, or hospital wastewater, poses significant environmental and public health challenges. Traditional wastewater treatment methods often fail to effectively remove the diverse and persistent pollutants present in these sources, including emerging chemical compounds or biological agents. To address these challenges, metal–organic frameworks (MOFs) have emerged as multifunctional materials offering promising advancements in wastewater remediation. These materials can be applied directly as pollutant adsorbents or used for pathogen removal due to their antimicrobial activity. Additionally, MOFs play a crucial role in Advanced Oxidation Processes (AOPs) due to their catalytic activity. When incorporated into electro-Fenton, Fenton-like, or photocatalytic processes, MOFs enhance the generation of oxidant radicals, enabling efficient wastewater decontamination. This comprehensive review explores the potential of MOFs, focusing specifically on their design, synthesis, and application as multifunctional materials for the inactivation of pathogens and the removal of organic pollutants. Moreover, it examines their characteristics, recent advances in synthesis techniques, and the mechanisms underlying their removal efficiency. The findings presented underscore the transformative potential of MOFs in achieving clean and safer water, contributing to sustainable environmental management and public health protection. Full article

This study investigates the synthesis and evaluation of ZnO/g-C₃N₄ composites as efficient green catalysts for advanced oxidation processes (AOPs) targeting the treatment of contaminated water. The composites were synthesized using a ternary deep eutectic solvent and physically–chemically characterized in detail, confirming their structural integrity and successful synthesis. Photocatalytic, photo-Fenton- and electro-Fenton-like experiments were conducted using Rhodamine B as a model contaminant to evaluate the catalytic performance, reuse and stability of the synthesized material. The synthesized ZnO/g-C₃N₄ composites demonstrated excellent photocatalytic activity under LED light (395 nm), achieving a pollutant removal of around 59% in 90 min. The combined effect of the designed catalyst and Fenton-like process, a photo-Fenton-like process, significantly improved this performance, achieving removal of close to 95% in 60 min due to the synergistic effects of the irradiation and H₂O₂ activation. Finally, the catalytic action of synthesized ZnO/g-C₃N₄ composites in the electro-Fenton-like process exhibited superior efficiency, achieving 90% removal within 45 min and kinetic constants four times higher than those of anodic oxidation alone. In addition, reuse studies confirmed the stability and catalytic activity of the composites for several cycles with high removal efficiencies, demonstrating their viability for long-term and scalable water treatment applications. These findings highlight the potential of ZnO/g-C₃N₄ composites synthesized through DES as a sustainable and cost-effective alternative for water remediation technologies. Full article

Fe-based metallic glass (MG) exhibits excellent performance as a heterogeneous catalyst in degradation but is rarely used as a working electrode in electro-Fenton (EF) systems. We used Fe₇₈Si₉B₁₃ MG as the working electrode to investigate the effect of the EF process on the degradation efficiency of p-nitrophenol (p-NP). The EF system had the highest catalytic efficiency (the reaction rate was 3.4 times that of chemical degradation) at a voltage of −1 V (vs. SCE) and showed 95.6% degradation of p-NP within 30 min. The electrode voltage accelerated the generation of hydroxyl radicals (·OH) in the system, thus promoting pollutant degradation. In addition, the Fe₇₈Si₉B₁₃ MG cathode demonstrated good structural stability and reusability after 10 cycles. Fe₇₈Si₉B₁₃ MG ribbons can serve as a suitable cathode material and provide potential optimization solutions for the degradation of organic pollutants. Full article

Electro-Fenton chemical mechanical polishing primarily regulates the generation of hydroxyl radicals (·OH) via the Fenton reaction through an applied electric field, which subsequently influences the formation and removal of the oxide layer on the workpiece surface, thereby impacting the overall polishing quality and rate. This study employs Pin–Disk friction and wear experiments to investigate the material removal behavior of single-crystal GaN during electro-Fenton chemical mechanical polishing. Utilizing a range of analytical techniques, including coefficient of friction (COF) curves, surface morphology assessments, cross-sectional analysis, and power spectral density (PSD) measurements on the workpiece surface, we examine the influence of abrasives, polishing pads, polishing pressure, and other parameters on the electro-Fenton chemical–mechanical material removal process. Furthermore, this research provides preliminary insights into the synergistic removal mechanisms associated with the electro-Fenton chemical–mechanical action in single-crystal GaN. The experimental results indicate that optimal mechanical removal occurs when using a W0.5 diamond at a concentration of 1.5 wt% combined with a urethane pad (SH-Q13K-600) under a pressure of 0.2242 MPa. Full article

This study investigated Rhodamine B (RhB) degradation by electro-Fenton (EF), anodic oxidation (AO), and their combination (EF/AO), using a carbon felt cathode coupled to a sub-stoichiometric titanium dioxide Magnéli phase (Ti₄O₇) anode or a platinized titanium (Ti/Pt) anode. The results indicated that operational parameters influenced the kinetics of electrochemical reactions. An increase in current density from 10 to 50 mA cm⁻² significantly enhanced the RhB degradation rate; 30 mA cm⁻² was the optimal current density, balancing both energy efficiency and degradation performance. Moreover, higher RhB concentrations required longer treatment. The Microtox^® bioluminescence inhibition test revealed a significant toxicity decrease of the dye solution during electrochemical degradation, which was highest with EF/AO. Similarly, total organic carbon removal was highest with EF/AO (90% at pH 3), suggesting more efficient mineralization of RhB and its by-products than with EF or AO. Energy consumption remained relatively stable with all oxidation processes throughout the 480 min electrolysis period. High-resolution mass spectrometry elucidated RhB degradation pathways, highlighting chain oxidation reactions leading to the formation of intermediates and mineralization to CO₂ and H₂O. This study underscores the potential of EF, AO, and EF/AO as effective methods for RhB mineralization to develop sustainable and environmentally friendly wastewater treatment strategies. Full article

Contaminants of emerging concern (CECs) in water, including pharmaceuticals and personal care products, represent a significant threat to environmental and human health. In this context, the electro-Fenton (EF) process has emerged as a highly effective technique for the removal of such pollutants. This study investigates the innovative use of tea waste material (TWM) in combination with copper-iron nanoparticles (FeCuNPs) to degrade a mixture of CECs. A central aspect of this research is the sustainable reuse of organic waste material, such as TWM, to support catalytic nanoparticles. This approach not only utilizes a resource that would otherwise be discarded but also promotes sustainability in the treatment of contaminated water, aligning with the principles of the circular economy. The as-prepared FeCuNPs@TWM catalyst was fully characterized, and critical parameters influencing the pollutant removal were assessed, including adsorption capacity, catalyst load, and applied current. Under optimized conditions, the EF process, enhanced by FeCuNPs@TWM, achieved complete degradation of the contaminants within 15 min of the electrochemical process, and the activity remained after five catalytic cycles. Results demonstrate that using tea waste functionalized with FeCu nanoparticles as a catalyst not only improves the efficiency of the EF process but also offers an eco-friendly and cost-effective alternative. Full article

Escalating herbicide pollution in natural water bodies necessitates further exploration of effective remediation strategies. This study investigated the electro-degradation of Terbutryn (TBT) at concentrations comparable to those encountered in agricultural practices. Anodic oxidation (AO), electro-Fenton (EF), and photoelectron-Fenton (PEF) were employed for TBT abatement. AO achieved moderate removal (68%), EF significantly improved efficiency (99%), and PEF surpassed both, reaching near complete removal (99.4%) by combining EF with UV light-induced •OH generation. Statistical analysis confirmed that optimizing treatment conditions was crucial. All three factors (current density, Fe²⁺ concentration, and initial TBT concentration) independently affected the PEF process ability to remove TBT pollutants. However, the interplay between these factors was even more important. Sufficient Fe²⁺ was critical for high TBT concentrations, and a balance between current density, Fe²⁺, and initial TBT concentration was necessary. Excessive levels of any could hinder COD removal. High-performance liquid chromatography (HPLC) was employed to monitor the degradation profile of by-products, including desthiomethyl Terbutryn, 2-hydroxy Terbutryn, and cyanuric acid. The analysis of these degradation products facilitated the proposal of a degradation pathway for Terbutryn. PEF stands out as a viable approach for TBT removal, especially in high-TBT wastewater. Full article