Search Results (280)

The textile industry releases effluents containing toxic contaminants such as azo dyes, which severely affect water quality and aquatic ecosystems. This study optimized the Fe⁰/H₂O₂/UV photo-Fenton process through Response Surface Methodology (RSM) using a Box–Behnken design applied to real textile wastewater. The process relies on in situ hydroxyl radicals (•OH) generation, which degrades refractory organic compounds. Under optimal conditions (pH 3.5, 0.5 g Fe⁰, and 0.55 mL H₂O₂), the system achieved complete color removal, 91% aromatic structures degradation, and an 80% COD reduction within 3 h. Statistical validation indicated an excellent model fit (R² = 1.0; Q² = 1.0), with strong correlation between experimental and predicted results. Spectroscopic analyses (UV–Vis and FTIR) further confirmed the cleavage of chromophoric and aromatic structures, indicating efficient pollutant degradation. Overall, the findings indicate that the Fe⁰/H₂O₂/UV system is an effective and sustainable technology for treating textile wastewater, offering strong potential for industrial-scale application. Full article

Water pollution caused by synthetic dyes is a major environmental concern due to their stability, toxicity, and resistance to conventional wastewater treatments. This study presents a sustainable approach for synthesizing zinc oxide (ZnO) nanoparticles using artichoke biomass (waste) as a green precursor and enhancing their visible light photocatalytic activity through phosphorus doping. ZnO nanoparticles were successfully synthesized via a simple green route and doped with 3–6% phosphorus using NH₄H₂PO₄. The structural, morphological, and optical properties of the resulting P-ZnO were characterized by XRD, SEM/EDX, TEM, FTIR, and UV-Vis spectroscopy. (6 wt%) Phosphorus doping effectively reduced the band gap from 3.06 eV to 2.95 eV, extended light absorption into the visible range, and improved electron–hole separation, resulting in enhanced photocatalytic performance. The P-ZnO nanoparticles were evaluated for methylene blue (MB) degradation under visible light in a photo-Fenton-like process, with H₂O₂ as an oxidant. The degradation efficiency reached 87.05% with 6% P-ZnO and further increased to 92.35% upon addition of H₂O₂. Durability and reusability tests demonstrated that the 6% P-ZnO catalyst maintained its activity and structural integrity over four consecutive cycles, indicating negligible loss of efficiency and excellent resistance to surface poisoning. The photocatalytic activity was strongly impacted by the quantity of catalyst, solution pH, and initial dye levels, with optimal performance at 0.3 g/L catalyst loading, pH 3, and lower MB concentrations. Full article

To address the limitations of traditional photo-Fenton reactions in antibiotic wastewater treatment, this study designed a continuous flat-plate photo-Fenton reactor based on the Fe₃O₄/TiO₂@Al₂SiO₅ fiberboard photocatalyst and applied it to the degradation of tetracycline HCl (TCH). The supported catalyst Fe₃O₄/TiO₂@Al₂SiO₅ was prepared via a calcination method, using the Al₂SiO₅ fiberboard as the carrier. This not only effectively addresses the issue of catalyst recovery but also enhances the dispersion and stability of the Fe₃O₄/TiO₂ catalyst as a support. Moreover, the catalyst mainly exhibited an amorphous structure. TiO₂ and Fe₃O₄ were successfully loaded onto the surface of the carrier. The operating parameters of the reactor were systematically optimized, and the optimal conditions were determined as follows: TCH influent concentration of 50 mg/L, hydraulic retention time (HRT) of 120 min, initial pH of 4.5, H₂O₂ dosage of 10 mmol/L, and ultraviolet (UV) light intensity of 2.36 kW/m³. Under these conditions, the TCH removal efficiency could reach over 90%. Active species trapping experiments indicated that hydroxyl radicals (•OH) were the main active substances responsible for TCH degradation. With the assistance of HPLC-MS/MS and GC-MS analyses, 19 types of degradation intermediates were identified. It was proposed that the TCH degradation pathway mainly included •OH-mediated hydroxylation addition reactions and demethylation reactions initiated by •OH and h⁺. The toxicity assessment showed that the toxicity of the degradation intermediates gradually decreased with the progress of the reaction. This reactor features high efficiency, stability, and easy operation, providing a feasible solution for the large-scale treatment of antibiotic wastewater. Full article

Electro-Fenton (EF) technology holds significant promise for degrading recalcitrant organic pollutants. Still, it faces distinct challenges in high-pollutant-load wastewater, including insufficient radical generation, electrode passivation, and mass transfer limitations. This review systematically organizes recent advances in material design and operational strategies to address these issues. We highlight innovative cathode materials (e.g., graphene-based structures, carbon nanotubes, and metal–organic frameworks), stable anodes such as boron-doped diamond, and catalysts tailored for harsh conditions. Key operational improvements are discussed, including pH adaptability, current density optimization, and oxygen supply enhancement. The integration of hybrid systems, such as bio-electro-Fenton and photo-electro-Fenton, is also examined. Looking forward, future research for treating high-pollutant load wastewater should focus on: (1) Developing electrodes and catalysts with superior antifouling properties and long-term stability in high-strength, complex wastewaters; (2) Constructing intelligent control systems capable of real-time response to water quality fluctuations for adaptive parameter optimization; (3) Exploring energy-efficient, self-sustaining EF systems coupled with renewable energy sources or incorporating energy recovery units. This review aims to provide a comprehensive reference for subsequent research endeavors and practical applications related to the treatment technology of EF systems in high-pollutant-load wastewater contexts. Full article

We studied the impact of some magnetic nanoparticles on two wastewater models of Rhodamine B dye, with 5 µM and 10 µM concentrations. The magnetite nanoparticles, synthesized by the co-precipitation technique, having less than 20 nm diameter and typical crystallinity features, were used to treat the Rhodamine B solutions and the results were analyzed using spectral measurements. The biological efficacy of the photo-Fenton-like reactions underlying this wastewater treatment was assessed using the V79-4 fibroblast cell line of Chinese hamster. The MTT test (colorimetric method with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) was applied for the toxicity testing of Rhodamine B 10 µM and 5 µM, initially, and degraded with 8 g/L MNP and 10 mM hydrogen peroxide for 120 min of UV exposure, the cell viability decreasing to 57–59% and 69–74%, respectively, for the dose of 80 µL/mL. Morphological changes were identified by microscopy analysis, such as membrane disruption, cell content extravasation, apoptotic bodies, and also colored spherical inclusions suggesting non-metabolized dye solution aliquots. The simpler molecules consisting of Rhodamine B degradation products, i.e., benzoic acid, benzyloxyamine, and phthalic acid were analyzed for their theoretical reactivity through quantum chemical computational modeling, which revealed a significant chemical potential compared to Rhodamine B. Full article

Cyanuric acid (CYA) is widely used as a chlorine stabilizer in swimming pools, but concentrations above 75 mg L⁻¹ cause overstabilization and loss of disinfection capacity. This study evaluated CYA removal by advanced oxidation processes, including heterogeneous photocatalysis, photo-Fenton, photo-persulfate, and anodic oxidation (AO). AO with boron-doped diamond anodes proved most effective, achieving up to 90% total organic carbon removal in ultrapure water. When applied to real swimming pool samples (118 and 251 mg L⁻¹ CYA), the process achieved significant CYA abatement, demonstrating its potential as a practical strategy to control overstabilization without additional chemicals. Full article

Chlorinated benzoquinones, such as 2,6-dichlorobenzoquinone (DCBQ), are toxic disinfection byproducts of growing concern in aquatic environments. Advanced oxidation processes, particularly photo-Fenton treatment, provide sustainable alternatives for their degradation. However, optimization is required to ensure not only the removal of the parent compound but also the reduction in harmful intermediates. This study evaluated the degradation of DCBQ (1.0 mM H₂O₂, 150 W UV, pH 3.0, 25 °C) with ferrous ion between 0 and 1.0 mg/L. DCBQ removal followed a second-order kinetic model, reaching complete degradation. Aromaticity-loss and water color degradation adjusted to kinetics of second-order, reflecting the sequential reduction in chlorinated hydroquinones and chlorophenols type intermediates, with marked decreases after 120 min at 0.8 mg/L. Results showed that increasing iron dosage enhanced both the rate of DCBQ disappearance and the removal of aromaticity, with complete pollutant degradation. Importantly, optimal ferrous ion dosages (20 mol DCBQ: 70 mol H₂O₂: 1 mol Fe²⁺) effectively limited the persistence of intermediates, as evidenced by significant decreases in color and aromaticity, while avoiding excessive turbidity. These findings demonstrate that fine-tuning iron dosage in photo-Fenton systems can maximize contaminant elimination and minimize secondary byproducts, reinforcing their role as sustainable solutions for wastewater remediation. Full article

The presence of various drugs in wastewater has generated growing concern about the contamination of water bodies. This requires urgent attention and the development of effective methods for their degradation in aquatic ecosystems. The present study evaluates the efficiency of metformin (MET) degradation via various photochemical processes—photolysis, H₂O₂ photodecomposition, photocatalysis, and photo-Fenton—using iron-pillared bentonite clays (Fe-PILC) as a catalyst. The influence of radiation wavelength (254 nm and visible light) was investigated, while MET degradation, H₂O₂ consumption, and total organic carbon (TOC) removal were monitored as key response variables. Structural characterization confirmed successful pillaring, increasing the surface area of bentonite from 35 to 246 m²/g, with iron content at 11 wt. % quantified by atomic absorption spectroscopy. Fe₃O₄ and FeO were identified using XPS, and a 2.08 eV band-gap energy was revealed via diffuse reflectance spectroscopy. Experiments were conducted at environmentally relevant MET concentrations (13,000 ng L⁻¹) in a 0.1 L batch photoreactor at 25 °C. The results demonstrate that (i) photo-Fenton was the most efficient process to remove and mineralize MET (100% degradation after 10 min and 83% mineralization after 90 min); (ii) Fe-PILC is effectively activated at λ < 700 nm, enabling 75% mineralization under visible light; (iii) hydroxyl radicals and valence band holes were the primary oxidative species driving MET oxidation; and (iv) cyanoguanidine and carboxylic acids were identified as main oxidation by-products via UHPLC. Pseudo-first-order kinetic constants were determined for all processes, offering insight into their relative efficiencies. Notably, the rate constant for photo-Fenton under visible light (0.406 min⁻¹) was comparable to that under UV -light (0.545 min⁻¹), highlighting the potential of visible light-driven treatments. Therefore, this study demonstrated the metformin degradation capability of iron-pillared clays under both visible and UV light. Full article

Bio-waste from potato shell agro-waste-based photocatalyst is introduced using potato shell integrated with Fe₃O₄ nanoparticles as a novel photocatalyst for photo-Fenton oxidation reaction. The catalyst was prepared via thermal activation of biochar, followed by co-precipitation of magnetite nanoparticles, resulting in a stable and reusable material. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques augmented with the energy dispersive X-ray spectroscopy (EDX) analysis with elemental mapping were used to assess the prepared sample. The prepared material, PtS200–Fe₃O₄, is then applied for oxidizing Procion Blue dye using biochar-supported magnetite catalyst. The oxidation process was evaluated under varying operational parameters, including pH, temperature, catalyst loading, oxidant dosage, and dye concentration. Results revealed that the system achieved complete dye removal within 20 min at 60 °C and pH 3, demonstrating the strong catalytic activity of the composite. Furthermore, the kinetic modeling is evaluated and the data confirmed that the degradation followed first-order kinetics. Also, the thermodynamic parameters indicated low activation energy with PtS200–Fe₃O₄ composite in advanced oxidation processes. The system sustainability is also assessed, and the reusability test verified that the catalyst retained over 70% efficiency after six consecutive cycles, highlighting its durability. The study confirms the feasibility of using biochar-supported magnetite as a cost-effective, eco-friendly, and efficient catalyst for the treatment of textile effluents and other dye-contaminated wastewater. Full article

This study introduces a novel photocatalyst derived from pumpkin peel bio-waste, calcined at 200 °C and incorporated with magnetite nanoparticles to form a hybrid PK-P/Fe₃O₄ catalyst. The material was characterized using X-ray diffraction (XRD), diffuse reflectance spectra (DRS), and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) mapping to confirm its structure and elemental distribution. The catalyst was applied for the photo-Fenton degradation of Synozol Red KHL dye under natural solution conditions (pH 5.7). Optimal parameters were achieved with a 20 mg/L catalyst and 200 mg/L H₂O₂, resulting in complete dye removal within 25 min of irradiation. The PK-P/Fe₃O₄ catalyst exhibited excellent reusability, retaining 72% removal efficiency after 10 successive cycles. Kinetic analysis confirmed a first-order model, while thermodynamic evaluation revealed a non-spontaneous, endothermic process with a low activation energy barrier, indicating energy-efficient dye degradation. These findings highlight the potential of bio-waste-derived PK-P/Fe₃O₄ as a sustainable, low-cost, and highly effective catalyst for treating dye-polluted wastewater under photo-Fenton conditions. Full article

Developing a robust Fenton-like catalyst through a feasible method is a significant challenge and is crucial for sustainability in wastewater treatment. Herein, we report a novel dual-phase H₂O₂ activation for ^•OH generation via both heterogeneous surface-mediated reactions and homogeneous radical propagation pathways. Mechanistic investigations revealed that the surface Fe²⁺/Fe³⁺ redox cycle was the primary driver of catalysis at pH 5. Notably, the catalyst produced fewer secondary pollutants than Fenton reactions and was effective in treating pollutants with high concentrations. The oxidative performance of the PAS-ISe was comparable to that of commercial FeSO₄·7H₂O in terms of chemical oxygen demand (COD) removal efficiency and reaction kinetics. Besides, the utility of the catalyst was 2-75-fold greater than that of state-of-the-art Fenton or photo-Fenton-like catalysts. A detailed techno-economic analysis confirmed the feasibility of this strategy and significant cost advantages over existing heterogeneous catalyst synthesis methods. This study concurrently proposes a low-cost approach to valorizing hazardous sludge and effectively treating industrial wastewater, which may support circular economic principles. Full article

Due to its efficiency, advanced oxidation processes (AOP), such as photo-Fenton, have become an alternative for removing emerging contaminants like paracetamol. The objective of this work was to perform a life cycle assessment (LCA) according to ISO 14040/44 for a heterogeneous photo-Fenton process catalyzed by Cu/Fe-pillared clays (PILC) for the removal of paracetamol from water. The study covered catalyst synthesis and four treatment scenarios, with inventories built from experimental data and ecoinvent datasets; treatment time was 120 min per functional unit. Environmental impacts for catalyst synthesis were quantified with ReCiPe 2016 (midpoint), while toxicity-related impacts of the degradation stage were assessed with USEtox™ (human carcinogenic toxicity, human non-carcinogenic toxicity, and freshwater ecotoxicity). Catalyst synthesis dominated most midpoint categories, the global warming potential for 1 g of Cu/Fe-PILC was 10.98 kg CO₂ eq. Toxicity results for S4 (photo-Fenton Cu/Fe PILC) showed very low values: 9.73 × 10⁻¹² CTUh for human carcinogenic and 1.29 × 10⁻¹³ CTUh for human non-carcinogenic. Freshwater ecotoxicity ranged from 5.70 × 10⁻⁴ PAF·m³·day at pH 2.7 (≥60 min) to 1.67 × 10⁻⁴ PAF·m³·day at pH 5.8 (120 min). Overall, optimizing pH and reaction time, are key levers to improve the environmental profile of AOP employing Cu/Fe-PILC catalysts. Full article

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 study focuses on the possibility of cleaning of industrial wastewater with catalytically active magnetic nanoparticles. Cobalt ferrite synthesized by the co-precipitation method was used, as prepared or after surface modification with a silica precursor. Electronic absorption spectra were recorded and analyzed to obtain the phenol degrading rate for various experimental design variants. Treating with pristine magnetic nanoparticles under simultaneous exposure to ultraviolet radiation resulted in similar degrading rates for 4 g/L and 8 g/L pristine nanoparticles, while, for silanized nanoparticles, the degrading rates were slightly increased. Along with ultraviolet irradiation and magnetic nanoparticles, hydrogen peroxide was also added, which led to significant enhancement of phenol degradation, for both pristine and silanized nanoparticles. It is proposed that photo-Fenton processes, triggered by metal ions at the nanoparticle surface and water photolysis and sustained by hydrogen peroxide decomposition, occurred to gradually decompose phenol to simpler compounds. Full article

This study investigates Fenton-based processes for textile dye degradation, focusing on Direct Red 28 (DR28), Reactive Blue 19 (RB19), and Reactive Black 5 (RBk5). Results reveal varying effectiveness of catalyst–radical combinations, with copper and peroxydisulfate consistently performing well, especially on RBk5 with 100% and 98.5% decolorization and total organic carbon (TOC) reduction, respectively. Iron faces limitations with DR28 due to sediment formation, resulting in 3.5% and 52.7% TOC removal when paired with hydroxyl and peroxydisulfate radicals, correspondingly. Unexpectedly, cobalt shows notable capabilities with RBk5, reaching 87.2% TOC removal, but performs poorly on the other two dyes, with less than 20% TOC removal when paired with hydroxyl radicals. Cost analysis highlights the cost-effectiveness of the standard photo-Fenton process for easy-to-degrade dyes with a cost of $0.174/g TOC removed, while copper emerges as a viable option for recalcitrant dyes, costing $0.371/g TOC removed. Overall, this research enhances understanding of catalyst–radical interactions on various dyes, a topic that is scarcely discussed in other research, and expands upon it by using techno-economic analysis for Fenton-based technologies for textile wastewater treatment, as a consideration for technology selection in actual application. Full article