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Search Results (154)

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34 pages, 3419 KB  
Review
Emerging Strategies for the Photoassisted Removal of PFAS from Water: From Fundamentals to Applications
by Lázaro Adrián González Fernández, Nahum Andrés Medellín Castillo, Manuel Sánchez Polo, Javier E. Vilasó-Cadre, Iván A. Reyes-Domínguez and Lorena Díaz de León-Martínez
Catalysts 2025, 15(10), 946; https://doi.org/10.3390/catal15100946 - 2 Oct 2025
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a diverse group of synthetic fluorinated compounds widely used in industrial and consumer products due to their exceptional thermal stability and hydrophobicity. However, these same properties contribute to their environmental persistence, bioaccumulation, and potential adverse health effects, [...] Read more.
Per- and polyfluoroalkyl substances (PFAS) are a diverse group of synthetic fluorinated compounds widely used in industrial and consumer products due to their exceptional thermal stability and hydrophobicity. However, these same properties contribute to their environmental persistence, bioaccumulation, and potential adverse health effects, including hepatotoxicity, immunotoxicity, endocrine disruption, and increased cancer risk. Traditional water treatment technologies, such as coagulation, sedimentation, biological degradation, and even advanced membrane processes, have demonstrated limited efficacy in removing PFAS, as they primarily separate or concentrate these compounds rather than degrade them. In response to these limitations, photoassisted processes have emerged as promising alternatives capable of degrading PFAS into less harmful products. These strategies include direct photolysis using UV or VUV irradiation, heterogeneous photocatalysis with materials such as TiO2 and novel semiconductors, light-activated persulfate oxidation generating sulfate radicals, and photo-Fenton reactions producing highly reactive hydroxyl radicals. Such approaches leverage the generation of reactive species under irradiation to cleave the strong carbon–fluorine bonds characteristic of PFAS. This review provides a comprehensive overview of emerging photoassisted technologies for PFAS removal from water, detailing their fundamental principles, degradation pathways, recent advancements in material development, and integration with hybrid treatment processes. Moreover, it discusses current challenges related to energy efficiency, catalyst deactivation, incomplete mineralization, and scalability, outlining future perspectives for their practical application in sustainable water treatment systems to mitigate PFAS pollution effectively. Full article
(This article belongs to the Section Environmental Catalysis)
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18 pages, 3305 KB  
Article
Removal of Cu(II) from Aqueous Medium with LDH-Mg/Fe and Its Subsequent Application as a Sustainable Catalyst
by Edgar Oswaldo Leyva Cruz, Ricardo Lopez-Medina, Deyanira Angeles-Beltrán and Refugio Rodríguez-Vázquez
Catalysts 2025, 15(10), 930; https://doi.org/10.3390/catal15100930 - 1 Oct 2025
Abstract
In this work, the removal of Cu(II) ions from an aqueous effluent was studied using an Mg/Fe layered double hydroxide (LDH) as the adsorbent. The material was synthesized and characterized before and after the adsorption process to identify structural and morphological changes induced [...] Read more.
In this work, the removal of Cu(II) ions from an aqueous effluent was studied using an Mg/Fe layered double hydroxide (LDH) as the adsorbent. The material was synthesized and characterized before and after the adsorption process to identify structural and morphological changes induced by copper uptake. Techniques such as X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and nitrogen physisorption (BET) were employed to confirm the interaction between the metal ions and the LDH surface. The LDH-Mg/Fe exhibited a high maximum adsorption capacity of 526 mg/g, and the adsorption kinetics followed a pseudo-second-order model, achieving over 90% removal of Cu(II) within 2.5 h. The Cu(II)-loaded material was subsequently evaluated as a sustainable catalyst in two applications: (i) an organic synthesis via “click” chemistry, reaching yields of up to 85%, and (ii) the decoloration of Congo Red via a Fenton-like process, achieving a decoloration efficiency of at least 84%. These dual uses demonstrate the potential of Cu(II)-loaded LDH as a cost-effective and environmentally friendly approach to simultaneous pollutant removal and catalytic valorization. Full article
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18 pages, 1918 KB  
Article
Sustainable Degradation of Acetaminophen by a Solar-Powered Electro-Fenton Process: A Green and Energy-Efficient Approach
by Sonia Herrera-Chávez, Silvia Gutierrez, Miguel A. Sandoval, Enric Brillas, Martin Pacheco-Álvarez and Juan M. Peralta-Hernández
Processes 2025, 13(8), 2633; https://doi.org/10.3390/pr13082633 - 20 Aug 2025
Viewed by 1301
Abstract
The presence of acetaminophen (ACTP) in aquatic environments has become a significant concern due to its environmental persistence and the potential formation of toxic transformation products. This study systematically compares the performance of three electrochemical advanced oxidation processes (EAOPs), electro-oxidation (EO), electro-Fenton (EF), [...] Read more.
The presence of acetaminophen (ACTP) in aquatic environments has become a significant concern due to its environmental persistence and the potential formation of toxic transformation products. This study systematically compares the performance of three electrochemical advanced oxidation processes (EAOPs), electro-oxidation (EO), electro-Fenton (EF), and solar photo-electro-Fenton (SPEF), for the degradation and mineralization of ACTP in aqueous media using boron-doped diamond (BDD) electrodes. Reactions were conducted under varying operational parameters, including current densities (15–60 mA cm−2), initial ACTP concentrations (10–30 mg L−1), and Fe2+ dosages. In the SPEF system, natural sunlight was utilized as the source of UV-A irradiation (30–35 W m−2). Among the evaluated processes, SPEF exhibited the highest degradation efficiency, achieving up to 97% ACTP removal and 78% chemical oxygen demand (COD) reduction within 90 min. High-performance liquid chromatography (HPLC) analysis identified phenol and catechol as major intermediates, suggesting a degradation pathway involving hydroxylation, aromatic ring cleavage, and subsequent oxidation into low-molecular-weight carboxylic acids. Kinetic modeling revealed pseudo-first-order behavior, with a maximum rate constant of 0.0865 min−1 under optimized conditions determined via Box–Behnken experimental design. Additionally, SPEF demonstrated enhanced energy efficiency (~0.052 kWh gCOD−1) and improved oxidant regeneration under solar radiation, highlighting its potential as an environmentally friendly and cost-effective alternative for pharmaceutical wastewater treatment. These results support the implementation of SPEF as a sustainable strategy for mitigating the environmental impact of emerging contaminants, especially in regions with high solar availability and limited technological resources. Full article
(This article belongs to the Special Issue Modeling and Optimization for Multi-scale Integration)
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22 pages, 1835 KB  
Article
Homogeneous and Heterogeneous Photo-Fenton-Based Photocatalytic Techniques for the Degradation of Nile Blue Dye
by Georgia Papadopoulou, Eleni Evgenidou and Dimitra Lambropoulou
Appl. Sci. 2025, 15(14), 7917; https://doi.org/10.3390/app15147917 - 16 Jul 2025
Cited by 1 | Viewed by 664
Abstract
In this study, the degradation of Nile Blue dye was investigated using homogeneous and heterogeneous photocatalytic methods based on the photo-Fenton reaction. More specifically, for homogeneous photocatalysis, the classical photo-Fenton (UV/Fe2+/H2O2) and modified photo-Fenton-like (UV/Fe2+/S [...] Read more.
In this study, the degradation of Nile Blue dye was investigated using homogeneous and heterogeneous photocatalytic methods based on the photo-Fenton reaction. More specifically, for homogeneous photocatalysis, the classical photo-Fenton (UV/Fe2+/H2O2) and modified photo-Fenton-like (UV/Fe2+/S2O82−) systems were studied, while for heterogeneous photocatalysis, a commercial MOF catalyst, Basolite F300, and a natural ferrous mineral, geothite, were employed. Various parameters—including the concentrations of the oxidant and catalyst, UV radiation, and pH—were investigated to determine their influence on the reaction rate. In homogeneous systems, an increase in iron concentration led to an enhanced degradation rate of the target compound. Similarly, increasing the oxidant concentration accelerated the reaction rate up to an optimal level, beyond which radical scavenging effects were observed, reducing the overall efficiency. In contrast, heterogeneous systems exhibited negligible degradation in the absence of an oxidant; however, the addition of oxidants significantly improved the process efficiency. Among the tested processes, homogeneous techniques demonstrated a superior efficiency, with the conventional photo-Fenton process achieving complete mineralization within three hours. Kinetic analysis revealed pseudo-first-order behavior, with rate constants ranging from 0.012 to 0.688 min−1 and correlation coefficients (R2) consistently above 0.90, confirming the reliability of the applied model under various experimental conditions. Nevertheless, heterogeneous techniques, despite their lower degradation rates, also achieved high removal efficiencies while offering the advantage of operating at a neutral pH without the need for acidification. Full article
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13 pages, 537 KB  
Review
An Overview of Electrochemical Advanced Oxidation Processes for Pesticide Removal
by Maiara A. P. Frigulio, Alexandre S. Valério and Juliane C. Forti
Processes 2025, 13(7), 2227; https://doi.org/10.3390/pr13072227 - 11 Jul 2025
Cited by 1 | Viewed by 811
Abstract
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 [...] Read more.
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
(This article belongs to the Special Issue Green Separation and Purification Processes)
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28 pages, 5779 KB  
Article
Theoretical Insight into Antioxidant Mechanisms of Trans-Isoferulic Acid in Aqueous Medium at Different pH
by Agnieszka Kowalska-Baron
Int. J. Mol. Sci. 2025, 26(12), 5615; https://doi.org/10.3390/ijms26125615 - 11 Jun 2025
Viewed by 679
Abstract
This study presents the first comprehensive theoretical investigation of the antioxidant mechanisms of trans-isoferulic acid against hydroperoxyl (HOO) radicals in aqueous solution, using the DFT/M062X/6-311+G(d,p)/PCM method. Thermodynamic and kinetic parameters, including reaction energy barriers and bimolecular rate constants, were determined for [...] Read more.
This study presents the first comprehensive theoretical investigation of the antioxidant mechanisms of trans-isoferulic acid against hydroperoxyl (HOO) radicals in aqueous solution, using the DFT/M062X/6-311+G(d,p)/PCM method. Thermodynamic and kinetic parameters, including reaction energy barriers and bimolecular rate constants, were determined for the three major pathways: hydrogen transfer (HT), radical adduct formation (RAF), and single electron transfer (SET). The results indicate that, at physiological pH, the RAF mechanism is both more exergonic and approximately eight-times faster than HT. At a higher pH, where the phenolate anion dominates, antioxidant activity is enhanced by an additional fast, diffusion-limited SET pathway. Isoferulic acid was also found to effectively chelate Fe2+ ions at pH 7.4 and above, forming stable complexes that could inhibit Fenton-type hydroxyl radical generation. Moreover, its strong UV absorption suggests a role in limiting photo-induced free radical formation. These findings not only clarify the antioxidant behavior of isoferulic acid but also provide novel theoretical insights applicable to related phenolic compounds. The compound’s multi-target antioxidant profile highlights its potential as a photoprotective agent in sunscreen formulations. Full article
(This article belongs to the Special Issue New Advances of Free-Radical Reactions in Organic Chemistry)
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18 pages, 2417 KB  
Article
Fate of Dissolved Organic Matter and Cooperation Behavior of Coagulation: Fenton Combined with MBR Treatment for Pharmaceutical Tail Water
by Jian Wang, Chunxiao Zhao, Feng Qian, Jie Su and Hongjie Gao
Molecules 2025, 30(12), 2520; https://doi.org/10.3390/molecules30122520 - 9 Jun 2025
Viewed by 537
Abstract
In this study, the treatment of pharmaceutical tail water (PTW) by coagulation, Fenton combined with membrane bioreactor (MBR), was studied. Optimal parameters were obtained according to batch experiment and central composite design (CCD). Results showed that Polymeric Ferric Sulfate (PFS) was the best [...] Read more.
In this study, the treatment of pharmaceutical tail water (PTW) by coagulation, Fenton combined with membrane bioreactor (MBR), was studied. Optimal parameters were obtained according to batch experiment and central composite design (CCD). Results showed that Polymeric Ferric Sulfate (PFS) was the best coagulant for original pharmaceutical tailwater due to less dosage and higher removal efficiency to TOC, COD, NH4+-N and UV254m, with the optimized pH = 7.25 and 0.53 g/L PFS dosage. The best coagulation performance was achieved when the mixer was stirred at 250 rpm for 3 min, 60 rpm for 10 min, and then left to stand for 60 min. Coagulation mainly removed organics with molecular weight above 10 kDa. After treated by coagulation, 43.1% TOC removal efficiency of PTW was obtained by Fenton reaction with 11.6 mmol/L H2O2, 3.0 mmol/L FeSO4, pH = 3.3 and T = 50 min. A type of common macromolecule aromatic amino acid compounds which located Ex = 250 nm and Em = 500 nm was the main reason that caused the high TOC concentration in the effluent. Stable COD and NH4+-N removal efficiencies in the MBR reactor within 10 d were observed when the mixture of pre-treated PTW (20%, v) and domestic sewage (80%, v) was fed into the MBR reactor, and over 95% COD and 50% NH4+-N were removed. One kind of amino acid similar to tryptophan was the prime reason that caused PTW resistance to be degraded. Analysis of the microorganism community in the MBR suggested that norank_f__Saprospiraceae was the key microorganism in degrading of PTW. Full article
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20 pages, 2486 KB  
Article
An Experimental Study on the Novel Ozone-Electro-Fenton Coupled Reactor for Treating Ofloxacin-Containing Industrial Wastewater
by Yifeng Han, Lifen Zhang, Keyan Liu, Jinliang Tao and Feng Wei
Water 2025, 17(11), 1649; https://doi.org/10.3390/w17111649 - 29 May 2025
Viewed by 616
Abstract
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 [...] Read more.
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
(This article belongs to the Section Wastewater Treatment and Reuse)
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15 pages, 3892 KB  
Article
Comparison of the Oxidation of 3,5-Dihydroxybenzoic Acid in Rainwater by UV/Fenton-like and UV/H2O2 Processes
by Patrícia S. M. Santos, Mónica P. S. Ferreira and Armando C. Duarte
Water 2025, 17(11), 1618; https://doi.org/10.3390/w17111618 - 27 May 2025
Viewed by 893
Abstract
Rainwater needs to be recognized as a natural water source for domestic use, but finding viable processes to remove its contaminants is essential. The aim of this work was to compare the UV/H2O2 and UV/Fenton-like processes for the oxidation of [...] Read more.
Rainwater needs to be recognized as a natural water source for domestic use, but finding viable processes to remove its contaminants is essential. The aim of this work was to compare the UV/H2O2 and UV/Fenton-like processes for the oxidation of 3,5-dihydroxybenzoic acid (3,5-DHBA) in rainwater. The reactions were assessed using ultraviolet-visible (UV-Vis) and molecular fluorescence spectroscopies, and the results showed the formation of new and similar chromophoric compounds in both processes, which were subsequently degraded. At environmentally relevant concentrations of chemical oxidants, namely H2O2 at 10−4 M, the chromophoric organic compounds in solution were degraded within 24 h by the UV/H2O2 process and within 4 h by the UV/Fenton-like process. However, when the concentration of H2O2 was increased by one order of magnitude for the UV/H2O2 process (from 10−4 M to 10−3 M), oxidation rates were similar and nearly complete after 4 h for both UV/H2O2 and UV/Fenton-like processes. These findings highlight that the presence of more oxidizing agents in the oxidation system improves the synergistic effect, leading to a greater contribution of the free radical oxidation pathway, particularly through hydroxyl radicals. Thus, by increasing the concentration of H2O2 in the UV/H2O2 process to 10−3 M, it was possible to achieve a similar level of oxidation (close to 100% after 4 h, as indicated by a decrease in fluorescence intensity) as the UV/Fenton-like process at environmentally relevant concentrations (10−4 M), but using fewer chemical reactants, since UV/H2O2 process does not require Fe(III) as catalyst and oxidant. Therefore, the UV/H2O2 process can be considered a simpler and cleaner process for removing organic contaminants from rainwater. Full article
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26 pages, 2810 KB  
Review
A Review of Various Advanced Oxidation Techniques for Pesticide Degradation for Practical Application in Aqueous Environments
by Mehary Dagnew, Qin Xue, Jian Zhang, Zizeng Wang, Anran Zhou, Min Li and Chun Zhao
Sustainability 2025, 17(10), 4710; https://doi.org/10.3390/su17104710 - 20 May 2025
Cited by 2 | Viewed by 2162
Abstract
Pesticides are chemicals used in agriculture, industry, and households to control pests and enhance crop yields but have emerged as pollutants in soil and water due to their presence in domestic and agricultural wastewater effluents. The World Health Organization (WHO) has identified the [...] Read more.
Pesticides are chemicals used in agriculture, industry, and households to control pests and enhance crop yields but have emerged as pollutants in soil and water due to their presence in domestic and agricultural wastewater effluents. The World Health Organization (WHO) has identified the development of pesticide resistance as a significant threat to global public health. Consequently, removing pesticides in aqueous environments has gained considerable attention. Numerous methodologies, including biological, physical, and chemical methods, have been employed for their treatment. Among these methods, advanced oxidation processes (AOPs) have garnered particular interest due to their fast reaction rates and strong oxidizing abilities. This review focuses on various AOPs such as Fenton and Fenton-like oxidation, ozonation, the UV/H2O2 process, electrochemical oxidation, photocatalytic oxidation, and the UV/O3 process. The review analyzes and summarizes the current applications of these AOPs for treating pesticides in aqueous environments. It also compares various AOPs treatment methods and discusses the challenges, drawbacks, advantages, and strategies for addressing these issues, and provides insights into the future prospects. Finally, it propose potential strategies and areas of improvement for future research to enhance the efficiency and sustainability of AOPs in practical application. Full article
(This article belongs to the Section Sustainable Water Management)
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37 pages, 1533 KB  
Systematic Review
Advanced Oxidation Process in the Sustainable Treatment of Refractory Wastewater: A Systematic Literature Review
by Jorge Alejandro Silva
Sustainability 2025, 17(8), 3439; https://doi.org/10.3390/su17083439 - 12 Apr 2025
Cited by 11 | Viewed by 4721
Abstract
More than 4 billion people yearly suffer from global water scarcity amid climate change, rapid population growth, and growing industrial activity. Due to the high concentrations of recalcitrant organic compounds, refractory wastewater is highly resistant to conventional biological treatment and represents a critical [...] Read more.
More than 4 billion people yearly suffer from global water scarcity amid climate change, rapid population growth, and growing industrial activity. Due to the high concentrations of recalcitrant organic compounds, refractory wastewater is highly resistant to conventional biological treatment and represents a critical obstacle for water reuse and sustainable water management. A systematic literature review of 35 peer-reviewed articles published from 2010 to 2025 is provided to evaluate the utilization and sustainability potential of advanced oxidation processes (AOPs) for treating recalcitrant wastewater. Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework, the review assesses numerous AOPs, such as ozonation, UV/H2O2, Fenton reactions, and photocatalysis, while also evaluating their performance, efficiency, and integration ability. The results show that AOPs demonstrate pollutant removal rates often greater than 96%, reduce sludge formation, and improve effluent biodegradability. They can be applied at different treatment stages, combined with any renewable energy systems, and therefore can scale and be sustained, thereby aligning with UN Sustainable Development Goal 6. AOPs provide a technically feasible and eco-friendly solution for higher quality wastewater treatment. In the face of increasing pressure on global water resources, and the urgent need for sustainable water resource management, this study offers valuable insights for policymakers and practitioners aiming to adopt resilient and circular strategies for water. Full article
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29 pages, 6092 KB  
Review
The Evolving Landscape of Advanced Oxidation Processes in Wastewater Treatment: Challenges and Recent Innovations
by Satyam Satyam and Sanjukta Patra
Processes 2025, 13(4), 987; https://doi.org/10.3390/pr13040987 - 26 Mar 2025
Cited by 18 | Viewed by 6572
Abstract
The increasing presence of persistent pollutants in industrial wastewater underscores the shortcomings of conventional treatment methods, prompting the adoption of advanced oxidation processes (AOPs) for sustainable water remediation. This review examines the development of AOPs, focusing on their ability to produce hydroxyl radicals [...] Read more.
The increasing presence of persistent pollutants in industrial wastewater underscores the shortcomings of conventional treatment methods, prompting the adoption of advanced oxidation processes (AOPs) for sustainable water remediation. This review examines the development of AOPs, focusing on their ability to produce hydroxyl radicals and reactive oxygen species (ROS) to mineralize complex pollutants. Homogeneous systems such as Fenton’s reagent show high degradation efficiency. However, challenges like pH sensitivity, catalyst recovery issues, sludge generation, and energy-intensive operations limit their scalability. Heterogeneous catalysts, such as TiO2-based photocatalysts and Fe3O4 composites, offer improved pH adaptability, visible-light activation, and recyclability. Emerging innovations like ultraviolet light emitting diode (UV-LED)-driven systems, plasma-assisted oxidation, and artificial intelligence (AI)-enhanced hybrid reactors demonstrate progress in energy efficiency and process optimization. Nevertheless, key challenges remain, including secondary byproduct formation, mass transfer constraints, and economic feasibility for large-scale applications. Integrating AOPs with membrane filtration or biological treatments enhances treatment synergy, while advances in materials science and computational modeling refine catalyst design and reaction mechanisms. Addressing barriers in energy use, catalyst durability, and practical adaptability requires multidisciplinary collaboration. This review highlights AOPs as pivotal solutions for water security amid growing environmental pollution, urging targeted research to bridge gaps between laboratory success and real-world implementation. Full article
(This article belongs to the Special Issue Advanced Oxidation Processes in Water Treatment)
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19 pages, 8318 KB  
Article
Activation of H2O2/PDS/PMS by Iron-Based Biochar Derived from Fenton Sludge for Oxidative Removal of 2,4-DCP and As(III)
by Chutong Ling, Renting Huang, Wei Mao, Zhiming Wu, Cui Wei, Anze Li and Jinghong Zhou
Water 2025, 17(5), 765; https://doi.org/10.3390/w17050765 - 6 Mar 2025
Cited by 3 | Viewed by 1625
Abstract
In this study, the catalytic performance of the Fenton sludge iron-based biochar catalyst (Fe@BC700), generated during the Fenton process, was investigated regarding its role in oxidizing 2,4-dichlorophenol (2,4-DCP) and As(III) from aqueous solutions in peroxymonosulfate (PMS), peroxydisulfate (PDS), and hydrogen peroxide (H2 [...] Read more.
In this study, the catalytic performance of the Fenton sludge iron-based biochar catalyst (Fe@BC700), generated during the Fenton process, was investigated regarding its role in oxidizing 2,4-dichlorophenol (2,4-DCP) and As(III) from aqueous solutions in peroxymonosulfate (PMS), peroxydisulfate (PDS), and hydrogen peroxide (H2O2) systems. The characteristics of the as-prepared catalyst, operational parameters of H2O2/UV/Fe@BC700, PDS/UV/Fe@BC700, and PMS/UV/Fe@BC700 systems, and the kinetics of 2,4-DCP degradation were evaluated. Fe@BC700 exhibited excellent capabilities for activating persulfate and an outstanding oxidant performance as a heterogeneous photocatalyst under UV irradiation. Among the tested systems, PMS/UV/Fe@BC700 showed the highest oxidation capabilities for both 2,4-DCP and As(III) within 40 min. The total organic carbon (TOC) removal efficiency for 2,4-DCP was up to 95.9% in the PMS/UV/Fe@BC700 system. The presence of free radicals in the PMS/PDS system included ·OH, SO4·−, and ·O2, which were facilitated by both UV irradiation and the catalyst. The by-products generated during the PMS/UV/Fe@BC700 treatment were identified via LC-MS analysis, which showed that catalytic degradation substantially reduced the chronic and acute toxicity of 2,4-DCP intermediates. The present study demonstrates that the iron-based biochar derived from Fenton sludge exhibited remarkable persulfate activation capabilities and was highly effective in removing 2,4-DCP and As(III). Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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13 pages, 2209 KB  
Article
Zeolite Modification for Optimizing Fenton Reaction in Methylene Blue Dye Degradation
by Ana P. Carvalho, José Costa, Angela Martins, António M. Fonseca, Isabel C. Neves and Nelson Nunes
Colorants 2025, 4(1), 10; https://doi.org/10.3390/colorants4010010 - 5 Mar 2025
Cited by 1 | Viewed by 1356
Abstract
Textile dyes often prove resistant to conventional wastewater treatment processes because of their complex molecular structures. Advanced oxidation methods, such as the Fenton reaction, have thus been recognized as a promising approach for environmental remediation by decomposing these pollutants. This work aimed to [...] Read more.
Textile dyes often prove resistant to conventional wastewater treatment processes because of their complex molecular structures. Advanced oxidation methods, such as the Fenton reaction, have thus been recognized as a promising approach for environmental remediation by decomposing these pollutants. This work aimed to study the efficacy of modified zeolites as catalysts in the Fenton reaction for dye degradation, with a particular emphasis on techniques for modifying zeolites and incorporating iron. The zeolite ZSM-5 was selected as the parent structure and underwent desilication and acid treatment procedures. Iron was introduced into the zeolite structure via two distinct methods: ion exchange and mechanochemistry. The modified zeolites with incorporated iron were evaluated in terms of their crystallinity, textural properties, and iron content before being used to degrade methylene blue solutions through the Fenton reaction. The reaction was monitored using UV-Vis spectroscopy, while the experimental outcomes were analyzed using pseudo-first-order and pseudo-second-order kinetic models. The research findings indicate that different treatment methods led to varying impacts on the zeolite properties, which in turn influenced the kinetic results. Moreover, it was observed that an enhancement in the degradation process can be achieved through the harmonious balance between a high iron content, increased mesoporosity (to facilitate diffusion), and adequate crystallinity (essential for maintaining structural integrity). Full article
(This article belongs to the Special Issue Feature Papers in Colorant Chemistry)
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16 pages, 2384 KB  
Article
A Comparative Study of Advanced Oxidation Processes for the Removal of the Antibiotic Sulfadoxine from Water—Transformation Products and Toxicity
by Panagiotis A. Bizirtsakis, Kyriaki Anagnostopoulou, Vasilis C. Sarasidis, Panagiota Petsi, Alexandra Moschona, Konstantinos V. Plakas and Dimitra A. Lambropoulou
Appl. Sci. 2025, 15(2), 793; https://doi.org/10.3390/app15020793 - 15 Jan 2025
Cited by 1 | Viewed by 1467
Abstract
Sulfonamides, including sulfadoxine (SDX), are widely used antibiotics, particularly for malaria treatment. However, their extensive use has led to environmental pollution, microbial resistance, and public health risks. Advanced Oxidation Processes (AOPs) offer promising methods to degrade such pollutants in water, though they may [...] Read more.
Sulfonamides, including sulfadoxine (SDX), are widely used antibiotics, particularly for malaria treatment. However, their extensive use has led to environmental pollution, microbial resistance, and public health risks. Advanced Oxidation Processes (AOPs) offer promising methods to degrade such pollutants in water, though they may generate more toxic by-products. This study evaluates three AOPs with different hydroxyl radical generation principles: the Fenton reagent (H2O2/Fe2+), hydrogen peroxide photolysis (UV-C/H2O2), and heterogeneous photocatalysis (UV-A/TiO2). Heterogeneous photocatalysis showed superior performance, achieving 100% degradation and 77% mineralization under optimized conditions. Further analysis explored the effects of UV dose, catalyst concentration, and pH on process efficiency. The influence of water matrices, including Ultrapure Water (UW), Tap Water (TW), and Surface Water (SW) from the Aliakmonas River, was also examined. High-Resolution Mass Spectrometry identified 11 SDX transformation products formed during photocatalysis, with their formation mechanisms reported for the first time. An ecotoxicity assessment using ECOSAR software revealed insights into the potential environmental impact of these by-products. Full article
(This article belongs to the Section Chemical and Molecular Sciences)
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