Search Results (163)

Fenton oxidation can contribute to meeting effluent standards for COD in actual wastewater treatment plant effluents. However, Fenton oxidation is prone to produce iron sludge waste. The application of heterogeneous Fenton-like systems based on Fenton iron mud carbon in wastewater treatment plants is essential for Fenton iron mud reduction and recycling. In this study, a Fenton iron mud carbon catalyst/Ferrate salts/H₂O₂ (FSC/Fe(VI)/H₂O₂) system was developed to remove chemical oxygen demand (COD) from secondary effluents at the pilot scale. The results showed that the FSC/Fe(VI)/H₂O₂ system exhibited excellent COD removal performance with a removal rate of 57% under slightly neutral conditions in laboratory experiments. In addition, the effluent COD was stabilized below 40 mg·L⁻¹ for 65 days at the pilot scale. Fe(IV) and ¹O₂ were confirmed to be the main active species in the degradation process through electron paramagnetic resonance (EPR) and quenching experiments. C=O, O-C=O, N sites and Fe⁰ were responsible for the generation of Fe(IV) and ¹O₂ in the FSC/Fe(VI)/H₂O₂ system. Furthermore, the cost per ton of water treated by the pilot-scale FSC/Fe(VI)/H₂O₂ system was calculated to be only 0.6209 USD/t, further confirming the application potential of the FSC/Fe(VI)/H₂O₂ system. This study promotes the engineering application of heterogeneous Fenton-like systems for water treatment. Full article

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

This paper presents a study on the optimization of 2,4-Dichlorophenoxyacetic (2,4-D) acid removal from synthetic wastewater by batch Fenton-Ozonation. The aim of this study is to evaluate the potential of the catalytic system Fe-L27 coupled to ozonation in the presence and absence of H₂O₂ as an effective and affordable technique for the treatment of organic pollutants in water. Fenton-like catalysts for the removal of 2,4-D in aqueous solutions were elaborated using catalysts synthesized by the wet impregnation method. The ACs and prepared catalysts were characterized by nitrogen adsorption–desorption isotherms at 77 K, TGA, XPS, SEM, and TEM. Their efficiency as Fenton-like catalysts was studied. In a first step, a response surface modeling method was employed in order to find the optimal parameters of the Fenton process, and then the optimal O₃/H₂O₂ ratio was established at laboratory scale. Finally, the investigated advanced oxidation processes were carried out at pilot scale. The results show that Fenton-like catalysts obtained by the direct impregnation method enhance the degradation rate and mineralization of 2,4-D. Full article

Sludge-derived biochar (SDB) synthesized by the pyrolysis of sludge is gaining enormous interest as a sustainable solution to wastewater treatment and sludge disposal. Despite the proliferation of general biochar reviews, a focused synthesis on SDB-specific advances, particularly covering the recent surge in multifunctional wastewater treatment applications (2020–2025), receives little emphasis. In particular, a critical analysis of recent trends, application challenges, and future research directions for SDB is still limited. Unlike broader biochar reviews, this mini-review highlights the comparative advantages and limitations of SDB, identifies emerging integration strategies (e.g., bio-electrochemical systems, catalytic membranes), and outlines future research priorities toward enhancing the durability and environmental safety of SDB applications. Specifically, this review summarized the advances from 2020 to 2025, focusing exclusively on functional modifications, and practical applications of SDB across diverse wastewater treatment technologies involved in adsorption, catalytic oxidation, membrane integration, electrochemical processes and bio-treatment systems. Quantitative comparisons of adsorption capacities (e.g., >99% Cd2+ removal, >150 mg/g tetracycline adsorption) and catalytic degradation efficiencies are provided to illustrate recent improvements. The potential of SDB in evaluating traditional and emerging contaminant degradation among the Fenton-like, persulfate, and peracetic acid activation systems was emphasized. Integration with membrane technologies reduces fouling, while electrochemical applications, including microbial fuel cells, yield higher power densities. To improve the functionality of SDB-based systems in targeting contamination removal, modification strategies, i.e., thermal activation, heteroatom doping (N, S, P), and metal loading, played crucial roles. Emerging trends highlight hybrid systems and persistent free radicals for non-radical pathways. Despite progress, critical challenges persist in scalability, long-term stability, lifecycle assessments, and scale-up implementation. The targeted synthesis of this review offers valuable insights to guide the development and practical deployment of SDB in sustainable wastewater management. Full article

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

The catalytic performance of copper in Fenton-like processes was investigated under conditions of elevated chloride concentrations. Model solutions were prepared containing four target pollutants (50 mg/L each), Cu (II) at 50 mg/L, and a stoichiometric dose of hydrogen peroxide sufficient for complete oxidation of the organic matter. Chloride levels ranged from low concentrations to those representative of both synthetic and natural seawater (36 g/L NaCl). An increase in chloride concentration consistently led to greater pollutant removal efficiency. The influence of pH on process performance was also assessed in saline and real seawater matrices. An optimal pH range between 6 and 7 was identified in both cases, where the reactivity of copper–chloride complexes was maximized while the formation of insoluble, catalytically inactive copper species was suppressed. Monitoring of pH, soluble copper concentration, and hydrogen peroxide consumption supported the conclusion that real seawater provides the most favorable conditions for copper–chloride catalyzed Fenton-like reactions. These results demonstrate the high potential of copper-based advanced oxidation processes in saline environments, particularly in applications where traditional methods exhibit limited efficiency. Full article

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

Copper-thiolate nanostructures, formed through the self-assembly of cysteine (Cys) and glutathione (GSH) with copper ions, offer a versatile platform for redox-active applications due to their structural stability and chemical functionality. In this study, Cu-Cys-GSH nanoparticles were synthesized and employed to develop a capacitive biosensor for the ultralow concentration detection of hydrogen peroxide (H₂O₂). The detection mechanism leverages a Fenton-like reaction, where H₂O₂ interacts with Cu-Cys-GSH nanoparticles to generate hydroxyl radicals (·OH) through redox cycling between Cu²⁺ and Cu⁺ ions. These redox processes induce changes in the sensor’s surface charge and dielectric properties, enabling highly sensitive capacitive sensing at gold interdigitated electrodes (IDEs). The influence of chirality on sensing performance was investigated by synthesizing nanoparticles with both L- and D-cysteine enantiomers. Comparative analysis revealed that the stereochemistry of cysteine impacts the catalytic activity and sensor response, with Cu-L-Cys-GSH nanoparticles exhibiting superior performance. Specifically, the biosensor achieved a linear detection range from 1.0 fM to 1.0 pM and demonstrated an ultra-sensitive detection limit of 21.8 aM, outperforming many existing methods for H₂O₂ detection. The sensor’s practical performance was further validated using milk and saliva samples, yielding high recovery rates and confirming its robustness and accuracy for real-world applications. This study offers a disposable, low-cost sensing platform compatible with sustainable healthcare practices and facilitates easy integration into point-of-care diagnostic systems. Full article

Ferrous oxalate dihydrate (α-FOD) was synthesized from Ecuadorian black sands for phenol removal from aqueous solutions. Visible light-driven photodegradation kinetics were studied by varying the initial pollutant concentration, solution pH, and α-FOD dosage and by adding peroxydisulfate (PDS), including quenching tests. A representative model of phenol photodegradation was obtained by the Langmuir–Hinshelwood mechanism over a large range of concentrations (apparent kinetic constant, k = 0.524 h⁻¹). Almost complete removal was reached within 1 h under dark + 9 h under visible irradiation. The degradation rate was slightly affected by pH in the range of 3 to 9, with a significant improvement at pH 11 (k = 1.41-fold higher). The optimal α-FOD dosage was ~0.5 g/L. Two regimes were observed when using PDS: first, a heterogeneous Fenton-like process during the first few minutes after PDS addition; second, pure photocatalysis to completely remove the phenol. When comparing the two systems, without and with PDS, the half-life time for pure photocatalysis was 2.5 h (after the lamp was switched on). When adding PDS (1.0 mM), the half-life time was reduced to a few minutes (5 min after PDS addition, phenol removal was 66%). The photocatalyst presented remarkable degradation efficiency up to five repeated cycles. Full article

Four different-sized carbon microspheres, CS, obtained by a facile hydrothermal method, are applied as a hard template for the preparation of a series of macroporous LaFeO₃. The average particle size of the CS obtained is between 0.350 and 0.700 µm. The macroporous LaFeO₃ are tested in a Fenton-like activation of peroxymonosulfate, PMS, for oxidation of tetracycline hydrochloride, TCH, in model water solution under visible-light irradiation. The effect of parameters such as type of irradiation, temperature of the reaction, and type of the water matrixes was tested. The oxidation of the pollutant TCH is evaluated by total organic carbon and organic nitrogen measurements. The results showed the superior catalytic activity of macroporous LaFeO₃ in comparison to pure LaFeO₃. Rate constants between 0.036 and 0.184 min⁻¹ at 25 °C were obtained. The activation energy for the process with the most active macroporous LaFeO₃ was 33.88 kJ/mol, a value lower than for the catalytic process with PMS only, proving the positive role of the macroporous LaFeO₃ for TCH degradation. Radical scavenger measurements showed that singlet oxygen, produced during the catalytic degradation process, was responsible for the performance of macroporous LaFeO₃/PMS/visible light for TCH degradation. The catalysts proved to be efficient and recyclable. Full article

Membrane technology is widely used in various aspects of wastewater treatment; however, single membrane technology has a series of disadvantages, such as high selectivity, poor recycling performance, and susceptibility to contamination. In this study, a treatment method combining an advanced oxidation process and membrane separation technology was proposed, and a geopolymer-based Fenton-like catalytic tubular membrane (GFM) was prepared by using H₂O₂ as a blowing agent by the direct foaming method. It was shown that the optimum conditions for the preparation of the membrane were a water glass modulus of 1.8 M, the addition of foaming agent of 1 mL, and a thickness of the membrane of 6.5 mm, with a flux of 6942 L·m⁻²·h⁻¹. Due to the characteristics of the tubular membrane, the possibility of adding hydrogen peroxide directly inside the membrane allows an optimal Fenton-like removal, which is better than outside the membrane, thus reducing the consumption of hydrogen peroxide. The tubular membrane has a multi-stage porous structure, high flux, and a high specific surface area (68.74 m²/g). The GFM/H₂O₂ Fenton-like system formed is capable of almost completely degrading all kinds of synthetic dyes under various stringent conditions, and the XRD, FTIR, and TG analyses and cycling tests showed that the GFM has excellent stability and a significant advantage in terms of reusability. Full article

The current work investigates the intensification process of the biological oxidation (BO) of a pharmaceutical effluent using ultrasound (US)-based pretreatment methods. US, in combination with chemical oxidants, like hydrogen peroxide (H₂O₂), Fenton, potassium persulphate (KPS), and peroxone, was used as a pretreatment technique to enhance the efficacy of BO, as BO alone could only bring about 16.67% COD reduction. The application of US under the optimized conditions of a 70% duty cycle, 120W of power, pH 2, and at a 30 °C temperature resulted in 12.3% COD reduction after 60 min, whereas its combination with oxidants at optimized loadings resulted in a higher COD reduction of 20% for H₂O₂ (2000 ppm), 23.08% for Fenton (1:1 Fe:H₂O₂), and 30.77% for the US + peroxone approach (400 mg/h of ozone with 2000 ppm H₂O₂). The pretreated samples did not produce any toxic by-products, as confirmed by a toxicity analysis using the agar well diffusion method. A cow-dung-based sludge was acclimatised specifically for use in BO. The treatment time for BO was set to 8 h, and the US + peroxone-pretreated samples showed a maximum overall COD reduction of 60%, which is about three times that observed with only BO. This work clearly demonstrates the enhancement of the biodegradation of a complex recalcitrant pharmaceutical effluent using a US-based pretreatment. Full article

Endocrine disruptors such as 17α-ethinylestradiol pose significant ecological risks in aquatic environments. This study assessed the catalytic performance of Fe- and Cu-impregnated delaminated clays (DCs) and layered double hydroxides (LDHs) in a Fenton-like process for EE2 removal. The effects of key parameters—including hydrogen peroxide concentration, initial contaminant load, and catalyst dosage—were analyzed using HPLC-QqTOF. Delaminated clays (DCs) demonstrated higher removal efficiencies compared to layered double hydroxides (LDHs), reaching 55% with Fe and 47% with Cu, while LDHs achieved 40% and 33% for Fe and Cu, respectively. Ecotoxicity was evaluated using bioassays (L. sativa, S. capricornutum, D. magna) and the Ames test. Notably, S. capricornutum exhibited 100% inhibition at the highest tested concentration, with IC₅₀ values of 11.2–12.4 for Cu and 31.5–32.7 for Fe. L. sativa was inhibited by Cu- and Fe-impregnated LDH/DC, with IC50 values of 71.0 (DC-Cu), 56.6 (DC-Fe), and 58.6 (LDH-Fe). D. magna exhibited 17–75% mortality when exposed to untreated EE2, while LC50 values confirmed Cu’s greater toxicity. The Ames test indicated no mutagenic effects. Integrating the Fenton-like process with complementary techniques is recommended to enhance efficiency. These findings highlight the need to optimize operational parameters for effective removal of 17α-ethinylestradiol. Full article

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

Herein, a heterogeneous Fenton-like catalyst was designed by immobilizing iron oxide (FeS) and nickel sulfide (NiS) on the surface of β-cyclodextrin (β-CD), creating a NiS/FeS@β-CD composite for degrading triphenylmethane cresol red dye. Varied instruments were used to study the physical and chemical characteristics of the NiS/FeS@β-CD catalyst. The appropriate catalytic conditions of the Fenton-like degradation of cresol red by NiS/FeS@β-CD were identified, clarifying that the higher degradation % fulfilled 99.86% with an adsorption % of 27.44% at a cresol red concentration = 50 mg/L, NiS/FeS@β-CD dose = 0.01 g, pH = 3, processing temperature = 30 °C, H₂O₂ concentration = 100 mg/L, and H₂O₂ volume = 1 mL. The kinetic assessments depicted the preference of the second order to represent the Fenton-like degradation of cresol red by NiS/FeS@β-CD. The mechanistic proposition of the adsorption/Fenton-like degradation of cresol red was understood using a quenching test and XPS analysis. Finally, to confirm the durability of NiS/FeS@β-CD, a reusability test was proceeded on the catalyst for five adsorption/Fenton-like degradation runs, with identifying the leaching concentrations of nickel and iron from the catalyst by ICP-OES after each run. Full article