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Bio-jarosite, an iron mineral synthesized biologically using bacteria, is a substitute for iron catalysts in the Fenton oxidation of organic pollutants. Iron nanocatalysts have been widely used as Fenton catalysts because they have a larger surface area than ordinary catalysts, are highly recyclable, and can be treated efficiently. This study aimed to explore the catalytic properties of bio-jarosite iron nanoparticles synthesized with green methods using two distinct plant species: Azadirachta indica and Eucalyptus gunni. The focus was on the degradation of dicamba via Fenton oxidation. The synthesized nanoparticles exhibited different particle size, shape, surface area, and chemical composition characteristics. Both particles were effective in removing dicamba, with removal efficiencies of 96.8% for A. indica bio-jarosite iron nanoparticles (ABFeNPs) and 93.0% for E. gunni bio-jarosite iron nanoparticles (EBFeNPs) within 120 min of treatment. Increasing the catalyst dosage by 0.1 g/L resulted in 7.6% and 43.0% increases in the dicamba removal efficiency for EBFeNPs and ABFeNPs with rate constants of 0.025 min−1 and 0.023 min−1, respectively, confirming their catalytic roles. Additionally, the high efficiency of both catalysts was demonstrated through five consecutive cycles of linear pseudo-first-order Fenton oxidation reactions.

The results obtained indicate that the catalysts synthesized: They were alginate-ferric clay and alginate-Fe, both were obtained by the casting method and their ability to decolorize the red dye 6 was evaluated. The materials were characterized by scanning electron microscopy (SEM) and elemental analysis by energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR) and a bioassay on Elongation of Lactuca sativa root was performed to verify the toxicity of the dye. In order to observer the effect that the availability of iron has on the efficiency of the process the Fe-alginate was compared with iron clay (iron-conditioned bentonite). The results indicate that the alginate film with iron clay presents a higher efficiency under UV light, with a discoloration percentage of 79%. On the other hand, under solar radiation, the alginate film with Fe showed a higher percentage of discoloration than 98%. The adsorption kinetics of the materials are best described by a first-order reaction, which provides important information about the behavior of the catalyst during the degradation process. Toxicity tests indicate that Lactuca sativa root growth is affected by iron residues and hydrogen peroxide in aqueous solutions. Toxicity Bioassay Diagram [ABSTRACT FROM AUTHOR]

The current study set out to assess and create long-term solutions for improving environmental performance concerning water use, wastewater production, and treatment at Syntan plant (glass-lined vessel unit) and application laboratory (small-scale leather retanning. Based on evaluations and analyses, best available techniques including water gauging, pressurized vessel washing, dedication of vessels to similar production, reuse techniques, developing commercial grade intermediate products from wash water, managing cooling water and developing reuse methods of reverse osmosis reject water were applied to reduce water consumption and effluent generation in process and non-process activities. Furthermore, the reduced effluent was subjected to treat using electrochemical processes, i.e., electrocoagulation and electro-Fenton, before it was drained to outside environment. As a result of the applications, 0%-100% change was measured in various process and non-process activities, whereas, 12.8%-100% reduction was measured in effluent. Soft cooling water consumption was reduced by 46.7%. The results of treated effluent parameters were compared and found the final removal efficiencies of total dissolved solids (51.4%), total suspended solids (99.2%), chemical oxygen demand (98.5%) and electric conductivity (67.7%). It is concluded that this study can be considered as a successful model to increased water efficiency in chemical industries, Furthermore, it could serve as a building block for the incorporation of cleaner and sustainable production approach into national agenda and to overcome stern issues of high-water and energy consumption and effluent management in different industries. [ABSTRACT FROM AUTHOR]

In this comprehensive investigation, we evaluate the efficacy of the Fenton process in degrading basic fuchsin (BF), a resistant dye. Our primary focus is on the utilization of readily available, environmentally benign, and cost-effective reagents for the degradation process. Furthermore, we delve into various operational parameters, including the quantity of sodium percarbonate (SPC), pH levels, and the dimensions of waste iron bars, to optimize the treatment efficiency. In the course of our research, we employed an initial SPC concentration of 0.5 mM, a pH level of 3, a waste iron bar measuring 3.5 cm in length and 0.4 cm in diameter, and a processing time of 10 min. Our findings reveal the successful elimination of the BF dye, even when subjected to treatment with diverse salts and surfactants under elevated temperatures and acidic conditions (pH below 3). This underscores the robustness of the Fenton process in purifying wastewater contaminated with dye compounds. The outcomes of our study not only demonstrate the efficiency of the Fenton process but highlight its adaptability to address dye contamination challenges across various industries. Critically, this research pioneers the application of waste iron bars as a source of iron in the Fenton reaction, introducing a novel, sustainable approach that enhances the environmental and economic viability of the process. This innovative use of recycled materials as catalysts represents a significant advancement in sustainable chemical engineering practices. [ABSTRACT FROM AUTHOR]

An overview of the latest advances in the design of active catalysts with the ability to promote (photo) Fenton processes in water from a Green Chemistry perspective is discussed herein. A critical evaluation of the most relevant advances has been disclosed, and a brief perspective is presented about what is needed to fill the gap of knowledge in this field. [ABSTRACT FROM AUTHOR]

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The addition of static mixers within reactors leads to higher productivity of a process and an additional increase in mass and energy transfer. In this study, we developed millireactors with static mixers using stereolithography, an additive manufacturing technology. Computational fluid dynamics (CFD) simulations were conducted to study the flow, identify potential dead volumes, and optimize the design of the millireactors. We produced five millireactors with various static mixers and one tubular reactor without static mixers, which served as a reference. The Fenton reaction was performed as a model reaction to evaluate the performance of the millireactors. We observed that some of the reactors with static mixers had air plugs that created a significant dead volume but still exhibited higher conversions compared to the reference reactor. Our results demonstrate the potential of stereolithography for producing intricate millireactors with static mixers, which can enhance the productivity of chemical processes. [ABSTRACT FROM AUTHOR]

Herein, the reinforced electron transfer ability of nano-galvanic Fe/Sn bimetallic particles deposited on talc for catalytic elimination of 2,4-dinitrotoluene (2,4-DNT) was investigated at different conditions. FESEM, XRD and FTIR characterization confirmed the successful and uniform formation of bimetallic galvanic particles on support. Ultrafast and intensified galvanic cell effects of bimetallic core-shell Fe/Sn nanoparticles enabled the nanocomposite to reach solely to 2,4-DNT removal efficiency of 91 % under the optimized condition. In addition, the synergistic combination of Fe/Sn galvanic nanocatalyst and H2O2 heterogeneous Fenton-like system, which took advantage of bimetallic Fe/Sn particles potential as viable adsorbent-reductant in pollution removal and effective source for generation of hydroxyl radicals, achieved 100 % 2,4-DNT removal within 10 min. The performance of this remediating process was evaluated under different nanocatalyst amount, pH, temperature, contaminant concentration, and H2O2 concentration. The removal process was in agreement with the pseudo-second-order kinetic model and the modified Langmuir isotherm model. Findings elucidated that the removal mechanism involved the electrostatic adsorption, galvanic oxidation–reduction and co-precipitation by nanocomposite, which was intensified by synergistic reaction of the hydroxyl radicals with pollutant. Overall, this study investigated the high potential of the combinational nZVI bimetallic galvanic nanoparticles and Fenton remediating processes, and the findings demonstrated the superior degradation capacity of the process as an innovative remediating approach.

An overview of the latest advances in the design of active catalysts with the ability to promote (photo) Fenton processes in water from a Green Chemistry perspective is discussed herein. A critical evaluation of the most relevant advances has been disclosed, and a brief perspective is presented about what is needed to fill the gap of knowledge in this field.

Hydrometallurgical processes utilize aqueous solutions to extract metals from ores, concentrates, or waste, resulting in a substantial consumption of freshwater and wastewater generation. This study investigates the treatment of wastewater produced during the hydrometallurgical silver extraction from in-mold structural electronics (IMSEs), aiming at minimizing discharge and ensuring water reuse. IMSE is an emerging technology that offers a lighter, cost-effective alternative to traditional PCBs. The generated wastewater contains high levels of COD (14.48 g/L) and iron (8.69 g/L). It was treated using a Fenton process by adopting a 22-full factorial design with center points to identify the best operative conditions. Following the analysis of variance (ANOVA) and model determination for COD abatement, Fisher's test was conducted to evaluate whether incorporating curvature into the model would enhance its fit to the experimental data. To further refine the process optimization, star points were added, resulting in a central composite design (CCD). The treatment resulted in a 93.6 % reduction in COD and a 99.9 % reduction in iron, with lime addition aiding in iron precipitation for water reuse. A quadratic model for COD removal indicated a high fit (R2 = 0.96), demonstrating the process's efficiency in reducing pollutants and promoting water reuse. Preliminary cost analysis revealed a total expenditure of 81.60 €/m³, significantly lower than the typical disposal costs of hydrometallurgical wastewater.

This exploration investigates integrated treatment systems combining advanced oxidation processes (Fenton and photo-Fenton) with biological methods for the effective elimination of stubborn organic compounds in simulated textile wastewater composed of azo Dichlorotriazine dye. A comprehensive optimization of key process factors including catalyst dosage, hydrogen peroxide quantity, irradiation duration, etc. was systematically conducted for both Fenton and photo-Fenton processes to realize maximum COD and color removal. Under ideal conditions (0.4 g/L photocatalyst, 1 mL/L H2O2, and 75-Watt UV intensity for 60 min), the photo-Fenton process realized 80% COD elimination and complete decolorization, meeting industrial discharge limits without needing extra biological treatment. Statistical models correlating process parameters to treatment efficiency were developed, giving important design insights. For Fenton, effluent COD exceeded discharge thresholds, so a post-biological treatment using activated sludge was essential to comply with regulations. This integrated Fenton–biological scheme utilizes synergism between chemical and biological processes for enhanced overall treatment. Notable economic benefits were achieved by photo-Fenton over conventional UV-only and UV/H2O2 methods regarding energy consumption and operating costs. Overall, this pioneering work successfully proves integrated advanced oxidation–biological systems as a superior, sustainable alternative to traditional techniques for economically removing obstinate pollutants, such as azo Dichlorotriazine dye, as it is a simulated textile wastewater treatment used to satisfy environmental standards. [ABSTRACT FROM AUTHOR]

In this work, methyl orange degradation was investigated using iron-modified dolomite prepared by simple impregnation of iron followed by calcination at 500 °C for 4 h. The natural dolomite before and after modification was subjected to comprehensive characterization utilizing various techniques. XRD and FTIR analysis confirmed the preservation of the dolomite structure and functional groups. The chemical composition obtained by XRF and EDX showed a successful insertion of iron into the dolomite structure with an increase from 1.3 to 5.3 wt % of this metal. The study of the reaction parameters showed that decolorization performance significantly depended on the temperature, catalyst dosage, H2O2 concentration and initial dye concentration. In addition, kinetics reaction followed the first-order model with rate constants in the range 3.2·10–2 to 45·10–2 min−1. The thermodynamic study revealed that the reaction was endothermic (ΔH° = 65.48 kJ/mol) and accompanied by a decrease in the disorder (ΔS° = -0.055 kJ/mol·K). The activation energy value (Ea = 63.98 kJ/mol) showed that the process was controlled by a surface reaction. The modelling using central composite design (CCD), with 40 experiments performed to complete the matrix of the experimental design established the optimum reaction conditions at C0 = 40 mg/L, 0.93 g/L of catalyst dosage and 7.26 mM of H2O2 concentration. The catalyst preserved high performance and stability after six successive cycles (90.23% decolorization efficiency) with a low iron leaching of less than 0.75 mg/L. The final effluent showed low ecotoxicity with a chemical oxygen demand (COD) lower than 8.23 mg O2/L. [ABSTRACT FROM AUTHOR]

The applicability of the life cycle assessment (LCA) to the Fenton process should be considered not only at the laboratory-scale but also at the full-scale. In this study, the LCA process was applied to evaluate the homogeneous Fenton process for the treatment of high salinity pharmaceutical wastewater. The potential environmental impacts were calculated using Simapro software implementing the CML 2001 methodology with normalization factors of 1995 world. Foreground data obtained directly from the full-scale wastewater treatment plant and laboratory were used to conduct a life cycle inventory analysis, ensuring highly accurate results. By normalized results, the Fenton process reveals sensitive indicators, primarily toxicity indicators (human toxicity, freshwater aquatic toxicity, and marine aquatic toxicity), as well as acidification and eutrophication impacts, contributed by hydrogen peroxide and iron sludge incineration, respectively. Overall, hydrogen peroxide and iron sludge incineration contribute significantly, accounting for at least 78% of these indicators. In sludge treatment phase, treatment of iron mud and infrastructure of hazardous waste incineration plants were the key contributors of environmental impacts, adding up to more than 95%. This study suggests the need to develop efficient oxidation processes and effective iron sludge treatment methods to reduce resource utilization and improve environmental benefits. [ABSTRACT FROM AUTHOR]

Prussian blue analogues (PBAs) have recently emerged as effective materials in different functional applications, ranging from energy storage to electrochemical water splitting, thence to more "traditional" heterogeneous catalysis. Their versatility is due to their open framework, compositional variety, and fast and efficient internal charge exchange, coupled with a self-healing ability that makes them unique. This review paper presents and discusses the findings of the last decade in the field of the catalytic and photocatalytic application of PBAs in water remediation (via the degradation of organic pollutants and heavy metal removal) and the catalytic oxidation of organics and production or organic intermediates for industrial synthesis. Analysis of the catalytic processes is approached from a critical perspective, highlighting both the achievements of the research community and the limits still affecting this field. [ABSTRACT FROM AUTHOR]

The main objective of this study was to use response surface methodology (RSM) and artificial neural network (ANN) to model and predict chemical oxygen demand (COD) and turbidity elimination from a synthetic dairy wastewater treated by the Fenton process. The experimental design was realized using RSM and, in particular, a face-centered composite (CCF) design. The responses were fitted by a second-order model in the form of quadratic polynomial equation, and the experimental data were analyzed by ANOVA (analysis of variance). The obtained results showed acceptable coefficients of determination (R2) for COD (0.836) and turbidity (0.870), indicating that the predicted values fit well with the real data when using quadratic models. Moreover, it was noticed from the iso-surface plots that the processing parameters have a great influence on COD. Among these factors, the most important one was the pH. However, they had a little effect on turbidity. The COD removal percentage was increased with pH decreasing and increasing reaction time, and iron sulfate concentration. In parallel, the same data generated from RSM were utilized to create the ANN model. In order to evaluate the accuracy of the predictions of the models, the R2, the mean square error (MSE), and the mean absolute error (MAE) were used, and the actual and predicted responses were compared. The results confirmed that the created ANN model has sufficient reliability in predicting the outputs for a different set of input values, with R2 of 0.980 for COD removal and 0.952 for turbidity removal. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) microplastics constitute a significant portion of plastic pollution in the environment and pose substantial environmental challenges. In this study, the effectiveness of the Fenton process and post-oxidation coagulation for the removal of non-weathered and UV-weathered PET microplastics (PET MPs) were investigated. A response surface methodology was used to investigate the interplay between PET concentration and ferrous ion (Fe2+) concentration. The models revealed an intricate interplay between these variables, highlighting the need for a balanced system for optimal PET MP removal. For non-weathered PET, the simultaneous increase in the concentrations of both PET microplastics and Fe2+ was found to enhance the removal efficiency. However, this synergistic effect was not observed in UV-weathered PET, which also demonstrated a more pronounced effect from the Fe2+ concentration. The statistical analysis provided a strong basis for the validity of the models. X-ray photoemission spectroscopy (XPS) further elucidated the mechanisms behind these findings, revealing that UV weathering results in surface changes, which facilitate hydroxyl radical oxidation. These findings underline the complexity of the Fenton process in PET microplastic removal and the different behavior of non-weathered and UV-weathered microplastics. This has significant implications for tailoring remediation strategies and underscores the importance of considering environmental weathering in these strategies. [ABSTRACT FROM AUTHOR]

The Fenton process is widely employed for decolorizing industrial wastewater. Therefore, it is imperative to construct a model for optimizing the operational parameters and estimating the efficiency of decolorization within this process. In this study, an artificial neural network (ANN) model was created based on experimental data provided by a previous researcher who examined the decolorization of Direct Red 16 dye (DR16) using a heterogeneous Fenton process within a microchannel reactor. This model was utilized to optimize and forecast the efficiency of decolorization in the Fenton process. The accuracy of the model was validated by comparing its outcomes with actual experimental data. To further improve the efficiency of decolorization, optimal operational parameters were ascertained utilizing the genetic algorithm method. The study revealed that as dye concentrations increased from 10 to 40 mg/l, decolorization efficiencies improved proportionately, peaking at 89.78 %. Optimal operational parameters for maximizing efficiency were identified as a feed flow rate of 1 ml/min, H2O2 concentration at 500 mg/l, Fe2+ concentration of 4 mg/l, and maintaining pH between 2.6 and 2.8. Insights derived from both experimental and model-generated data were used to analyze the impact of operational parameters on decolorization efficiency.

The current study set out to assess and create long-term solutions for improving environmental performance concerning water use, wastewater production, and treatment at Syntan plant (glass-lined vessel unit) and application laboratory (small-scale leather retanning. Based on evaluations and analyses, best available techniques including water gauging, pressurized vessel washing, dedication of vessels to similar production, reuse techniques, developing commercial grade intermediate products from wash water, managing cooling water and developing reuse methods of reverse osmosis reject water were applied to reduce water consumption and effluent generation in process and non-process activities. Furthermore, the reduced effluent was subjected to treat using electrochemical processes, i.e., electrocoagulation and electro-Fenton, before it was drained to outside environment. As a result of the applications, 0%–100% change was measured in various process and non-process activities, whereas, 12.8%–100% reduction was measured in effluent. Soft cooling water consumption was reduced by 46.7%. The results of treated effluent parameters were compared and found the final removal efficiencies of total dissolved solids (51.4%), total suspended solids (99.2%), chemical oxygen demand (98.5%) and electric conductivity (67.7%). It is concluded that this study can be considered as a successful model to increased water efficiency in chemical industries, Furthermore, it could serve as a building block for the incorporation of cleaner and sustainable production approach into national agenda and to overcome stern issues of high-water and energy consumption and effluent management in different industries.

Natural organic matter (NOM) serves as a precursor for the formation of carcinogenic disinfection by-products when not adequately removed by conventional water treatment processes. The degradation of NOM by heterogeneous Fenton processes is particularly attractive because it results in prospects of zero sludge discharge. This work reports on NOM degradation and adsorption via the heterogeneous Fenton process using phytogenic zero-valent iron nanoparticles (nZVI) synthesised from green tea extract (Camellia sinensis) and supported on kaolin (fK-nZVI). The synthesised material was characterised using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) analysis. Morphological analysis of SEM images and BET values revealed an increase in the surface area from 11.64 m2 · g−1 for kaolin to 27.07 m2 · g−1 for the kaolin-supported nZVI (K-nZVI), thus presenting an ideal modification for effective adsorption. Fenton process parameters were optimised, that is, H2O2 concentration (5 mM) and pH (4.5). At equilibrium, the adsorption by the fK-nZVI system was 0.127 mg · g−1, a value higher than reported in other adsorption systems at equivalent adsorbent dosage and NOM concentration. The promising results obtained in this study indicate heterogeneous Fenton degradation and adsorption can be a viable and effective method for NOM removal from aqueous media. HIGHLIGHTS The Brunauer–Emmett–Teller surface area of kaolin-supported nZVI increased by 57%.; Maximum removal of bovine serum albumin (BSA) was achieved when the pH was set at 4.5 and H2O2 concentration at 5 mM.; Fenton processes increased the chemisorption capacity and subsequent oxidation of BSA by 44%.;

The study investigated antioxidant biomarkers in Dreissena polymorpha to evaluate the efficiency of Fenton process (FP) in Organized Industrial Zone Wastewater (OIZW) treatment. Antioxidant enzymatic activities, including superoxide dismutase (SOD) and catalase (CAT), glutathione peroxidase (GPX), non‐enzymatic antioxidants (GSH) and the indicator of lipid peroxidation (TBARS) were measured in D. polymorpha in response to treated OIZW by FP. The performance of the FP has been optimized with response surface methodology (RSM). The optimum conditions (reaction time, and H2O2 and Fe2+ concentration) for OIZW by the FP process were determined. The results showed that the highest COD removal efficiency (83.94 %) was obtained when as Fe2+ concentration=402.35 mg/L, H2O2 concentration=4100.30 mg/L, and reaction time=10.10 min (desirability=1.000). SOD and CAT enzyme was decreased in the 1/25 diluted OIZW group compared to control group. CAT and SOD enzyme activities were increased after treatment compared to control groups. No statistically significant changes were observed in GSH levels and GPx activities. TBARS levels were increased 1/25 diluted OIZW exposure groups compared to the control group. TBARS levels were decreased after treatment. The results revealed that antioxidant parameters are useful biomarkers for determining the treatment efficiency of the FP. [ABSTRACT FROM AUTHOR]

Dyes rejected by various industries are one of the major hazardous pollutants to be quantified. It is therefore necessary to remove the dye before discharging it into the main water stream. In this study, the catalytic degradation of methyl green (MG) cationic dye by Fenton process 'Fe2+/H2O2' was modelled using four artificial intelligence (AI) models; artificial neural networks (ANN), support vector machine (SVM), random forest (RF) and gradient boosting regressor tree (GBRT) and compared with response surface methodology (RSM). The models were analysed by considering four factors that affect the degradation process: concentration of MG, concentration of Fe2+, concentration of H2O2 and temperature. The objective of this analysis was to quantify the accuracy of prediction of four types of AI models along with RSM model. Sensitivity analyses comprising correlation coefficient, mean square error (MSE) were employed to assess the adequacy of the proposed models. The mean square error (MSE) values corresponding to the validation set for MG degradation were 0.434, 0.232, 0.307, 0.177 and 0.223 while the respective coefficient of determination values were 0.9658, 0.95780 0.9440, 0.9677 and 0.9574 for the ANN, SVM, RF, GBRT and CCD models, respectively. According to these results, the AI and RSM gave a high accuracy in predicting the degradation of the methyl green dye. The four AI models have satisfactory goodness-of-fit, robustness and predictive ability compared to RSM model. The GBRT performs slightly better performance than the other models. Maximum degradation (De% > 98) was achieved at an initial dye concentration of 20 mg/L, a Fe2+ concentration of 7 mM, a hydrogen peroxide dose of 25 mM, and a temperature of 50°C. Overall, the applied statistical analysis of the results indicates that the four methods can be employed as an AI models for monitoring and prediction the degradation by Fenton process. [ABSTRACT FROM AUTHOR]

The use of heterogeneous Fenton process combined with biological and physical treatment of sanitary landfill leachate has been evaluated. Leachate used in this study was collected from the drainage system of a landfill in Borg El-Arab city – Egypt. As a pre-treatment step, the collected leachate was subjected to ammonia stripping at pH 10.0 for 6 h to reduce the ammonia toxicity for the subsequent biological treatment steps. In this step, over 80% of the ammonia content of the leachate could be removed. Then, the ammonia-stripped leachate was subjected to heterogeneous Fenton process or to aerobic biological treatment. At its optimum operating conditions namely; 37.18 g/L H2O2, 5 g/L catalyst and a reaction time of 4 h, the use of heterogeneous Fenton process achieved COD removal up to 73%. Corresponding COD removal obtained after biological treatment was 68%. To select the best sequence of the treatment steps, the ammonia-stripped sanitary landfill leachate was subjected to two treatment trains. The first one was biological treatment followed by heterogeneous Fenton process; while, the second was heterogeneous Fenton process followed by biological treatment. The highest reductions of the organic compounds and ammonia were achieved after using biological treatment followed by the heterogeneous Fenton process. The use of this treatment configuration achieved total COD, BOD and NH4-N removals of 88%, 84% and 96% respectively. Accordingly, the proposed treatment train can be considered effective in the treatment of landfill leachate and environmental protection. [ABSTRACT FROM AUTHOR]

The issue of antibiotic residue causing environmental contamination must be addressed with urgency and seriousness. The present study used a heterogeneous Fenton-subcritical water process to degrade synthetic liquid waste containing a mixture of tetracycline and erythromycin. MIL-88B(Fe) was utilized as a catalyst, produced using the solvothermal method at 150 °C. Utilizing SEM, XRD, and nitrogen sorption, the catalyst was characterized. In addition, the degradation capability of heterogeneous Fenton subcritical water was compared to that of the conventional Fenton process, subcritical water, and homogeneous Fenton-subcritical water processes. The experiment results demonstrated that the heterogeneous Fenton-subcritical water process was preferable to other methods for degrading tetracycline and erythromycin. This study found that tetracycline degraded at a maximum rate of 91.3% and erythromycin at 77.7%. MIL-88B(Fe) experiments were also conducted to determine the catalysts' efficacy.

A Fenton-like catalyst MnO2-Fe3O4/SiO2 is synthesized via a two-step approach. The prepared composite has a mesoporous structure and a high surface area of 190 m2/g. The XRD pattern describes a specific peak of Fe3O4 magnetite on the baseline of amorphous silica. Furthermore, the FTIR spectra not only show the height assigned to stretching vibrations of Si-O-Si bonds, and Fe–O–Fe connections but also exhibit a small peak that matches the Mn–O bonds. SEM images exhibit a porous network structure of the composites with some holes among 30 – 100 nm clusters. The activity of the catalyst is determined in a paracetamol degradation as a Fenton oxidation. The paracetamol removal efficiency is at 85.6% with the optimal condition as initial pH 3, catalyst dosage of 0.15 g/50mL and H2O2 concentration of 1 mL/50 mL. In addition, the catalyst can be reused at least 5 times with a low reduction of the catalytic activity from 85.6% to 80.8%. The experiment results open a direction that has high efficiency in the treatment process of excess paracetamol in pharmacy wastewater.

Paint industry wastewater is hard to treat due to its complex and changing structure. In the study, the Fenton oxidation process was used to treat this wastewater. The pH levels required for the Fenton process were obtained without any chemical addition other than Fenton's catalyst and oxidant. Reaction time, H2O2 concentration, and Fe2+ concentration were chosen as independent parameters for the experimental design employing Taguchi orthogonal arrays. These independent parameters were varied at four different levels to find out their effects on the removal efficiencies of the dependent parameters. Chemical oxygen demand (COD) and color were chosen as the dependent parameters. The removal efficiencies of COD and color were obtained at 69% and 98%, respectively. According to optimization studies, the degree of effect of H2O2 concentration, Fe2+ concentration, and reaction time on COD removal performance were obtained as 12.01%, 23.87%, and 21.67%, respectively. Moreover, the degree of effect on color removal performance of H2O2 concentration, Fe2+ concentration, and reaction time were obtained as 15.08%, 19.00%, and 22.42%, respectively. Furthermore, the results from this experimental optimization study show that the synergistic effect of Fenton oxidation on COD removal provides additional removal efficiency reaching 190% compared with H2O2's real oxidation potential. [ABSTRACT FROM AUTHOR]

In this study, color and chemical oxygen demand (COD) removal efficiencies from sugar industry wastewater were compared by applying homogeneous and heterogeneous Fenton oxidation processes. The parameters effecting the oxidation process such as iron ion concentration, catalyst amount, hydrogen peroxide concentration, pH, temperature and reaction time were examined and optimum experimental conditions were determined. Synthesized Fe(III)/SnO2 was used as catalyst in the heterogeneous Fenton process. It was aimed to eliminate the iron-containing sludge formation, which was the disadvantage of the homogeneous Fenton process, by the heterogeneous Fenton process. Under the optimum conditions, in the homogeneous Fenton process 81% color and 70% COD removal efficiency and in the heterogeneous Fenton process 94% color and 80% COD removal efficiency were achieved. Finally, a cost analysis was made. The cost analysis result showed that the heterogeneous Fenton was more economical. These results showed that the heterogeneous Fenton method is more suitable for sugar industry wastewater treatment. [ABSTRACT FROM AUTHOR]

In this study, based on the advantage of having high organic content of sludge both sludge treatment and electricity generation in the microbial fuel cell were investigated. The hydrolysis step of anaerobic digestion which is known as rate‐limiting step was tried to accelerate with the pre‐treatment methods such as Fenton and thermal/alkaline for sludge stabilization in the microbial fuel cell. The chemical oxygen demand and organic matter removal were 53% and 64% in the anaerobic chamber of the microbial fuel cell fed with raw sludge, respectively. In the microbial fuel cell fed with pre‐treated sludge using Fenton Process, these removal efficiencies were found to be 59% and 60%, respectively, while in thermal/alkaline microbial fuel cells were 83.3% and 85%, respectively. The current densities in microbial fuel cells fed with raw sludge, Fenton process sludge and thermal/alkaline sludge were 0.002, 0.221 and 38 mA/cm2, respectively. As a result, it can be concluded that, the microbial fuel cell fed with pre‐treated sludge can be used for both the sludge treatment and the electricity generation by improving the decomposition of organic matter and accelerating the rate‐limiting step in the anaerobic chamber. [ABSTRACT FROM AUTHOR]

Azo dye is widely used in the textile industry since it is cost effective and simple to use. However, it becomes a continuous source of environmental pollution due to its carcinogenicity and toxicity. Various methods had been used to remove the azo dye in solution. One of the famous and frequently used is the Fenton process. The Fenton process is one of the advanced oxidation processes where iron catalysed hydrogen peroxide to generate hydroxyl radical. Treating azo dyes in solution requires a catalyst to enhance the process of degradation. Herein, high entropy alloys (HEAs) have been proposed as a catalytic material to enhance the performance of Fenton process for azo dye degradation. HEAs have been reported as a promising catalyst due to its high surface area. The higher the number of active sites, the higher the rate of azo dye degradation as more active sites are available for adsorption of azo dyes. The results have shown that HEAs can be used as a catalyst to fasten the Fenton reaction since the degradation time is proven to be shorter in the presence of HEAs. The method derived from the result of this study will contribute in treating azo dyes for wastewater management in the Fenton process.

The addition of static mixers within reactors leads to higher productivity of a process and an additional increase in mass and energy transfer. In this study, we developed millireactors with static mixers using stereolithography, an additive manufacturing technology. Computational fluid dynamics (CFD) simulations were conducted to study the flow, identify potential dead volumes, and optimize the design of the millireactors. We produced five millireactors with various static mixers and one tubular reactor without static mixers, which served as a reference. The Fenton reaction was performed as a model reaction to evaluate the performance of the millireactors. We observed that some of the reactors with static mixers had air plugs that created a significant dead volume but still exhibited higher conversions compared to the reference reactor. Our results demonstrate the potential of stereolithography for producing intricate millireactors with static mixers, which can enhance the productivity of chemical processes.

This exploration investigates integrated treatment systems combining advanced oxidation processes (Fenton and photo-Fenton) with biological methods for the effective elimination of stubborn organic compounds in simulated textile wastewater composed of azo Dichlorotriazine dye. A comprehensive optimization of key process factors including catalyst dosage, hydrogen peroxide quantity, irradiation duration, etc. was systematically conducted for both Fenton and photo-Fenton processes to realize maximum COD and color removal. Under ideal conditions (0.4 g/L photocatalyst, 1 mL/L H2O2, and 75-Watt UV intensity for 60 min), the photo-Fenton process realized 80% COD elimination and complete decolorization, meeting industrial discharge limits without needing extra biological treatment. Statistical models correlating process parameters to treatment efficiency were developed, giving important design insights. For Fenton, effluent COD exceeded discharge thresholds, so a post-biological treatment using activated sludge was essential to comply with regulations. This integrated Fenton–biological scheme utilizes synergism between chemical and biological processes for enhanced overall treatment. Notable economic benefits were achieved by photo-Fenton over conventional UV-only and UV/H2O2 methods regarding energy consumption and operating costs. Overall, this pioneering work successfully proves integrated advanced oxidation–biological systems as a superior, sustainable alternative to traditional techniques for economically removing obstinate pollutants, such as azo Dichlorotriazine dye, as it is a simulated textile wastewater treatment used to satisfy environmental standards.

Prussian blue analogues (PBAs) have recently emerged as effective materials in different functional applications, ranging from energy storage to electrochemical water splitting, thence to more “traditional” heterogeneous catalysis. Their versatility is due to their open framework, compositional variety, and fast and efficient internal charge exchange, coupled with a self-healing ability that makes them unique. This review paper presents and discusses the findings of the last decade in the field of the catalytic and photocatalytic application of PBAs in water remediation (via the degradation of organic pollutants and heavy metal removal) and the catalytic oxidation of organics and production or organic intermediates for industrial synthesis. Analysis of the catalytic processes is approached from a critical perspective, highlighting both the achievements of the research community and the limits still affecting this field.

In an era of increasing environmental awareness, it is very important to work towards eliminating or at least reducing as many harmful industrial substances as possible. However, the implementation of green chemistry methods for wastewater treatment can be difficult especially due to complexity, the high cost of reagents, and the required long process time. This paper focuses on using waste iron (WI) to remove two kinds of amaranth dye commonly used in industry. To enhance the process, UV irradiation and hydrogen peroxide were used. The novelty of the research was the use of efficient and reusable WI as a heterogeneous catalyst in the process. WI material characteristics was done before and after the process using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray fluorescence (XRF). Zeta potential, size characterization, circularity, and direct band gap were also determined. As a result of treatment complete decolorization of both dyes was achieved, as well as 99% absorbance removal after 15-min process time. The total organic carbon (TOC) decrease after 60-min process time was in the range from 86.6 to 89.8%. Modified pseudo-second-order reaction reflects obtained results of treatment efficiency. Treatment results, confirmed by WI material characterization, indicate satisfactory stability of the catalyst and good oxidation capacity. [ABSTRACT FROM AUTHOR]

In this study, Chemical Oxygen Demand (COD) removal efficiency from wood processing wastewaters by Fenton Process (FP) and Photo Electro Fenton Process (PEFP) were examined. Important operating parameters such as pH, Fe+2 concentration/(amper for PEFP), H2O2 concentration and reaction time were optimized. Optimum operation conditions of the FP were pH 3.5, 1.4 gr/L Fe2+ concentration and 50 gr/L H2O2 concentration and 150 min. reaction time while they were pH 3.00, 9.99 mA/cm² current density and 70 gr/L H2O2 concentration and 150 min reaction time in PEFP. At the optimum conditions, COD removal efficiency of FP and PEFP was 91% and 99%, respectively. Sludge production of FP was 20% higher than PEFP at the optimum conditions. [ABSTRACT FROM AUTHOR]

This study evaluated the COD removal performances of classical-Fenton and photo-Fenton Processes by different prediction models. To optimize both Fenton processes performed in batch reactors, the effects of H2O2 dose, Fe(II) dose, H2O2/Fe(II) rate, and contact time were determined as the independent variables of the prediction models. Besides response surface methodology, three neural networks were used to more reliably and effectively predict the behaviors of dependent variables at different values of relevant parameters. Multi-Layer Perceptron trained by Levenberg–Marquardt (MLP-LM), Multi-Layer Perceptron and Single Multiplicative Neuron models trained by Particle Swarm Optimization algorithm (MLP-PSO; SMN-PSO) were studied. Models' prediction performances were evaluated by Root-Mean-Square Error (RMSE) and Mean Absolute Percent Error criteria. Regression analysis was applied to determine the performance of the best model. The results from both criteria indicated that SMN-PSO model produced the best predictive results in almost all cases. Moreover, the key process parameters were determined by applying the genetic algorithm to SMN-PSO model outputs. The optimized conditions achieved the optimum removal with over 99% desirability. The optimum Fe(II) dose was determined as 399.99 mg/L in both Fenton processes. H2O2 dose was found as 726.18 and 894.07 mg/L and removal efficiencies were achieved 86.50 and 87.49% for classical Fenton and photo-Fenton, respectively. As a result, it will be possible to simulate and improve the different Fenton processes and determine the optimum process parameters by the obtained data in the treatment of wastewater with similar characteristics without many experiments, which are difficult and costly. [ABSTRACT FROM AUTHOR]

The higher production of HO· concentration associated with the presence of a Cu2+ co-catalyst in a Fe2+/H2O2 system is reported. The synergistic effect of the co-catalyst was investigated to evaluate the possibility of further enhancement of the oxytetracycline degradation. Several experiments with different ratios of Cu2+ to Fe2+ (0.5:5, 1:5, 2:5, 3:5, and 4.5:5) were conducted to show the effect of Cu2+ co-catalysis. The parameters studied for the degradation of OTC were the initial pH (2–7), initial concentration of OTC (5–20 mg/L), and H2O2 concentration (25–180 mg/L). Almost all OTC was completely degraded at the end of the process (60 min) by (Cu2+–Fe2+)/H2O2 when the Cu2+/Fe2+ ratio was 1:5 and initial concentrations were 20 mg/L, 60 mg/L, 2 mg/L, and 0.4 mg/L of OTC, H2O2, Fe2+, and Cu2+, respectively. The effect of natural solar light was also investigated on the degradation of OTC in the Fe2+/Cu2+ system at 60 min. The results showed that the Cu2+–Fe2+/H2O2 system was more effective than the Fe2+/H2O2 system for OTC degradation, and less inhibition effect was found with the coexistence of Cl−, CO32−, HCO3−, NO3−, and NO2− ions. [ABSTRACT FROM AUTHOR]

Wastewater from the production of meat and bone meal, due to the high load of organic matter and suspended solids, is a significant problem in the process of its treatment. In this work, we examined the method of treating this wastewater using coagulation with hydrogen peroxide and the Fenton process. Treatment variants included the use of variable Fe2+/H2O2 ratios of 1:5–1:30, variable doses of 3–18.0 g/L H2O2, and 5–10 mL/L of coagulant PIX 113. The calculated reduction degrees showed that, regardless of the treatment variant used, the greatest reduction was obtained for turbidity (100%), phosphorus (99%), followed by color (97%), chemical oxygen demand (70%), and Kjeldahl nitrogen (48%). The proposed treatment options can be used as a preliminary stage in treating wastewater from the production of meat and bone meal.

Extant literature has demonstrated that conventional water treatment processes especially in developing countries struggle in completely removing detrimental organic loads. Emerging research delineates nanomaterials such as nanoscale zero valent iron (nZVI) to have excellent performance in organic matter removal from aqueous media. In this work, nZVI particles were prepared from the liquor of commercially available green tea and supported on kaolin (K‐nZVI) and investigated as an adsorbent for natural organic matter (NOM) sequestration from aquatic media. Further, the asymmetric ceramic membrane was prepared by incorporating the developed adsorbent on a concrete support for the removal of NOM. A Fenton cleaning strategy was developed to mitigate fouling. The Brunauer–Emmett–Teller (BET) results revealed the developed adsorbent surface area was greater compared to raw kaolin (27.07 and 11.64 m3 g−1, respectively). The scanning electron microscopy (SEM) imagery of the developed adsorbent showed the particle staking was presented as paper slices of varying sizes, an indication of dispersed particles with characteristic plate‐like fragments. The synthesized membrane exhibited a pHZPC value of 4.79 ± 0.03. This meant at pH above 4.79 ± 0.03, the membrane would be negatively charged, and conversely at pH below the pHZPC value. Membrane fouling due to bovine serum albumin (BSA) deposition showed a 50% flux decline in the first 60 min, coinciding with the rapid adsorption capacity within the same time frame. The optimal cleaning parameters of pH (4.5) and H2O2 (5 mM) gave the best flux recovery rates. This work demonstrated an efficient Fenton cleaning strategy to regenerate the developed membrane. [ABSTRACT FROM AUTHOR]

In this study, degradation of oxytetracycline (OTC) and chlortetracycline (CTC) was investigated by Fenton process. In experimental studies conducted for this purpose, different values of pH, Fe2+ concentration, H2O2 concentration and reaction time were tested as important parameters for the Fenton process and optimum conditions for OTC and CTC removal were determined. For both antibiotics, the optimum values of the parameters in the Fenton process were the same, and these values were found to be 3 for pH, 20 mg/L for Fe2+ concentration, 25 mg/L for H2O2 concentration, 5 min for reaction time. Under these optimum conditions, OTC degradation was 100%, CTC degradation was 99.68%, chemical oxygen demand (COD) removal efficiency for oxytetracycline (O-COD) was 89.6%, COD removal efficiency for chlortetracycline (C-COD) was 88.5%. These results show that the Fenton process is an effective method that can be used for OTC and CTC degradation. [ABSTRACT FROM AUTHOR]

The degradation and mineralization of 4-chlorophenol (4-CP) by advanced oxidation processes (AOPs) was investigated in this work, using both of UV/H2O2 and photo-Fenton UV/H2O2/Fe+3 systems.The reaction was influenced by the input concentration of H2O2, the amount of the iron catalyst, the type of iron salt, the pH and the concentration of 4-CP. A colored solution of benzoquinon can be observed through the first 5 minutes of irradiation time for UV/H2O2 system when low concentration (0.01mol/L) of H2O2 was used. The colored solution of benzoquinon could also be observed through the first 5 minutes for the UV/H2O2/Fe+3 system at high concentration (100ppm) of 4-CP. The results have shown that adding Fe+3 to the UV/H2O2 system enhanced the rate of 4-CP oxidation at a molar ratio of H2O2/Fe+3/4-CP equals to 13/0.4/1 by a factor of 7. This reduced the consumption of H2O2 by a factor of 6 and the irradiation time required for complete degradation was reduced by a factor of 6. The experimental results have shown that the optimum reagents for a complete degradation of 4-CP(50ppm) were H2O2.=0.005mol/L, Fe+3=0.16*10-3 mol/L under acidic condition (pH=3) and irradiation time of 15 min for the UV/H2O2/Fe+3 system with a molar ratio of H2O2/Fe+3/4-CP equals to 13/0.4/1.