Fenton-like Oxidation Research Articles

Hydrophobic microenvironment mediated photo-Fenton beads confining free radicals in vicinity of water-soluble contaminants for enhancing water purification

Heterogeneous photo-Fenton process can produce reactive oxygen species (ROS) on the catalysts surface; however, it will decay quickly in bulk solution, resulting in low utilization rate. Herein, we design a hydrophobic microenvironment mediated polymer beads (HMPBs) as an alternative platform to immobilize Fenton-like catalysts for efficiently confining ROS in hydrophilic area and improving mass transfer. Molecular dynamics simulation predicted that diffusion of reactants will slow down on mixed hydrophilic/hydrophobic interface so that the short-lived ROS can oxidize contaminants efficiently. Consequently, the optimal HMPBs exhibits remarkably increased degradation kinetic constants, which is about 4.4 and 1.5-fold improvement in comparison with single hydrophilic and hydrophobic beads, respectively. The continuous flow degradation system with packed column type is further developed to expanded its application for Fenton-like oxidation. Altogether, this work revealed the wettability effects on the Fenton chemstrity, manifesting a deeper understanding of ROS-based reaction behaviors on special wettability interface.

Removal of tetracycline from aqueous solution by beach sand-based silica

As a class of broad-spectrum antibiotics, tetracyclines find extensive use in human, veterinary, and aquacultural applications. Releasing tetracycline in the form of parent or derivative compounds into the aquatic environment is extremely dangerous to human health. This study investigates the ability of silica (SiO2) extracted from Beureunut beach sand to remove tetracycline in an aqueous solution by combining adsorption and Fenton-like oxidation. The beach sand was used as a precursor, and it was reacted with a sodium hydroxide solution at 80 °C before being precipitated with sulfuric acid and dried. The extraction yielded 9.22 g of silica, which was then further characterized using Fourier transform infrared (FT-IR) spectroscopy. Prior to the adsorption test, the stability of tetracycline solution was evaluated at two different temperatures (11 °C and 30 °C). The findings of a 6-day stability test performed in water showed that tetracycline was more stable at 11 °C than at 30 °C. The adsorption capacity of silica was found to be 1.68 mg/g (17.00%) at 50 mg/L tetracycline concentration after 3 hours of contact time. Meanwhile, the adsorption method combined with the Fenton-like process increased the percentage of tetracycline removal from 17.00% to 56.32%. In conclusion, combining adsorption and Fenton-like processes provides an option for greatly increasing the ability of beach sand-based silica as a potential adsorbent to remove tetracyclines from water.

Fenton-Like Oxidation Systems for Destruction of Azo Dyes in Aqueous Solutions

The kinetic regularities of degradation of the azo dye methyl orange (MO) in photoinitiated oxidizing systems have been studied using a xenon lamp (UV–Vis) as a source of quasi-solar radiation. According to the efficiency and rate of dye destruction, the considered oxidizing systems can be arranged in the following series: {UV–Vis} {UV–Vis/S2O2-8} {S2O2-8/Fe0} {UV–Vis/S2O2-8/Fe0} {UV–Vis/S2O2-8/Fe2+}. It has been established that in photoinitiated Fenton-like oxidizing systems there is not only complete conversion of MO but also its deep mineralization in aqueous solution; a decrease in the content of total organic carbon reaches 60%. In this case, the specific catalytic activity of iron ions in the combined system {UV–Vis/S2O2-8/Fe0} is much higher than in {UV–Vis/S2O2-8/Fe2+}. Using inhibitors of radical reactions, it has been proved that in the combined system {UV–Vis/S2O2-8/Fe0} both hydroxyl and sulfate anion radicals take part in oxidative degradation. An inhibitory influence of anions (bicarbonates, chlorides, nitrates, and sulfates) and natural dissolved organic matter (Suwanee River 2R101N) on the process of mineralization of total organic carbon during oxidative destruction of MO in the combined system {UV–Vis/S2O/Fe0} has been found.

Fenton-Like Oxidation Systems for Destruction of Azo Dyes in Aqueous Solutions

Fenton-Like Oxidation Systems for Destruction of Azo Dyes in Aqueous Solutions

Mediated electron transfer process in α-MnO2 catalyzed Fenton-like reaction for oxytetracycline degradation

In Fenton-like oxidation, the catalyst directly influences the reaction mechanism for the degradation of pollutants from water. Here, a α-MnO2 catalyst (OAm-1) was synthesized via a self-assembly method with the assistance of a surfactant. OAm-1 possessed a large specific surface area of 221 m2/g, abundant mesoporous structures and a large proportion of Mn(III). Further characterization exhibited that OAm-1 had abundant oxygen vacancies and excellent reducibility and conductivity. The adsorption and catalytic ability of OAm-1 were studied in the degradation of oxytetracycline (OTC) via the activation of hydrogen peroxide (H2O2). Through the radical quenching experiments, electron resonance spectroscopy (EPR), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR) analysis, Mn(III) of OAm-1 was proved to be the active sites for the chemisorption of OTC. Systematic electrochemical experiments and analysis have shown that a process of electron transfer mediated by OAm-1 occurred between the pollutant and H2O2 during a Fenton-like reaction. This work experimentally verifies the electron transfer process dominated nonradical mechanism over α-MnO2, which is helpful for understanding the catalytic mechanism of the Fenton-like oxidation.

Unraveling synergistic mechanisms of polyacrylamide coagulation and Fe2+/CaO2 Fenton-like oxidation to enhance sludge dewatering

Enhancing sludge dewatering can effectively reduce the operational costs of wastewater treatment plants. In the present study, a synergistic process combining polyacrylamide (PAM) coagulation with Fe2+/CaO2 Fenton-like oxidation was proposed to improve the performance of sludge dewatering. The findings indicate that pre-addition of PAM before Fe2+/CaO2 treatment yielded superior dewatering performance, reducing the water content from 78.6% to 73.1% and the capillary suction time (CST) from 32.9 s to 19.5 s, respectively. Even with a CaO2 dosage of 62.5 mg/g DS, the ultimate pH of the filtrate remained near neutral, and effective dewatering performance was consistently attained. Results of particle size and zeta potential revealed that the addition of PAM enhanced the particle size by electric neutralization and bridging, thus accelerating sludge filtration. Furthermore, Fe2+/CaO2 facilitated the conversion of hydrophilic organic matter in tightly bound EPS (TB-EPS) to soluble EPS (SB-EPS) and loosely bound EPS (LB-EPS), and lysis of the sludge cells, contributing to a decrease in water content. Molecular analysis of EPS through Fourier-transform infrared spectroscopy (FT-IR) further elucidated the breakdown of hydrophilic functional groups by this combined method. Additionally, the changes of Fe2+, Fe3+, and H2O2 concentrations were investigated to explore the mechanism of enhanced sludge dewatering from a kinetic perspective. Ultimately, the concentration of typical heavy metals in the treated sludge sample significantly decreased, leading to a reduction in environmental risks. Overall, this study employed the safe and stable CaO2 as the source of H2O2, combined with Fe2+ to form a Fenton-like system. Meanwhile, PAM was utilized to flocculate the sludge firstly, and then Fe2+/CaO2 oxidation system was carried out to enhance sludge dewatering, which provided a promising sludge dewatering approach with potential applications.

Boron-doped porous carbon boosts electron transport efficiency for enhancing Fenton-like oxidation capacity: High-speed driving of Fe(III) reduction

Herein, Fenton-like cocatalysts with sufficient activity and stability were developed to accelerate the Fe(III)/Fe(II) redox cycle, thereby enhancing the oxidation capacity of Fe(III)/H2O2 system. A porous engineering coupled with heteroatom doping strategy was adopted to prepare high-performance cocatalysts represented by boron-doped porous carbon (BPC). A small amount of BPC input (0.04 g/L) drives the efficient degradation of pollutants in Fe(III)/H2O2 system via •OH-dominated radical pathway. Based on characterization results, the doping of boron species optimizes the pore structure of cocatalysts and improves their co-catalytic activity. Meanwhile, boron content increase steers the reduction of Fe(III) in BPC/Fe(III)/H2O2 system through an “expressway” with higher electron transport efficiency. Theoretical calculations suggested the “electron porter” effect of BCO2 on BPC to produce free Fe(II) for H2O2 activation. The continuous-flow device using BPC as a membrane component has excellent performance in purifying micro-polluted water. This study provides a novel co-catalytic Fenton-like method for water remediation.

An ultrasonic-assisted Synthesis, Characterization, and application of Nano-Fe3O4/TiO2 as nano-catalyst for the removal of organic dye by Like-Photo-Fenton reactions

In this research, Fe3O4 nanoparticles were synthesized via a simple co-precipitation method. Subsequently, these nanoparticles were used to synthesize TiO2-Fe3O4 nanocomposites via solvothermal ultrasonic-assisted method. Obtained nanomaterials Fe3O4 and TiO2-Fe3O4 were structurally characterized by UV–visible, XRD, and SEM-EDS. Synthesized nano-catalysts were tested as catalysis of organic dye degradation. Furthermore, an optimization study was conducted to evaluate selected TiO2-Fe3O4 nanocomposites to degrade Methylene Blue (MB) in an aqueous solution through Fenton-like reactions. Several experimental variables, including pH (from 2 to 8), H2O2 concentration (from 10-2 to 5.10-1M), catalyst amount (20 to 80 mg), and target organic compound concentrations, were tested in order to optimize the Fenton-like catalytic activity of the TiO2-Fe3O4 as a nano-catalyst to degrading MB under ambient light conditions (natural sunlight). The results showed that TiO2-Fe3O4 had an efficient degradation rate of up to 85% for MB at the optimal pH 3, H2O2 at 10-1M and 40 mg/L catalyst amount. Also, the results showed the good reusability of TiO2-Fe3O4 as a nanophotocatalyst. Also, based on the results of the scavenging agent experiments, hydroxyl radicals and superoxide radicals play an important role in methylene blue (MB) photodegradation. Finally, a possible mechanism for the photocatalytic degradation of MB was proposed. In this study, the synthesis and application of TiO2-Fe3O4 nanocomposite as a nano-catalyst in the Fenton-like oxidation process demonstrated a promising eco-friendly method for treating organic pollutants in water.

Raw clays from Morocco for degradation of pollutants by Fenton-like reaction for water treatment

Three raw clays from Morocco were used as heterogeneous catalysts for Fenton-like oxidation of organic pollutants in water. The selected pollutants were two dyes used in the textile industry, Congo Red (CR) and Tartrazine (Tar, known also as a food coloring compound, E102) and Caffeine (Caf), a stimulant drug present in popular beverages such as coffee and tea, commonly used in Morocco. Two different processes were used for their degradation: (i) Fenton-like reaction; and (ii) electro-Fenton-like reaction. Process (i) was used for Tar and Caf degradation in the presence of clays from different region of Morocco (Middle Atlas - ClayMA, Fez - ClayF, and Ourika - ClayO), the best results being obtained with ClayO and ClayMA, on which 60.0% and 23.4% of conversion and 41.0% and 20.5% of mineralization were achieved for Tar and Caf, respectively. Process (ii) was used for degrading CR by clay-modified electrodes (CME) using the rawclays from Fez and Ourika regions (ClayF and ClayO). The stability of the CME was assessed by cyclic voltammetry studies, which proved that they are stable in the experimental conditions used. The electrodegradation of CR dye, performed without hydrogen peroxide in the reaction medium, achieve 67.0% of mineralization at the end of electrolysis (2 h).

Enhanced Fenton-like oxidation (Vis/Fe(III)/Peroxydisulfate): The role of iron species and the Fe(III)-LVF complex in levofloxacin degradation

Traditional Fenton and Fenton-like processes are affected by the sluggish kinetics of Fe(II) regeneration and Fe(III) accumulation. This research revealed that the degradation efficiency of pollutants was significantly increased by adding Fe(III) to the Vis/PS system. A mechanism is proposed in which photosensitivity pollutants can boost Fe(III) to produce Fe(II) under visible light irradiation. Intriguingly, Fe(III) rapidly combines with LVF in aqueous environments to form Fe(III)-LVF complexes. This research confirms that Fe(III)-pollutant complexes are generated. The proportion of complexes are calculated using mathematical models. Furthermore, the production of Fe(IV) is verified in the Vis/PS/Fe(III) system, which also plays a vital role in boosting LVF degradation. Overall, this study provides comprehensive insights into the degradation mechanism of micropollutants, involving hydroxyl radical (OH∙), Fe(IV), and Fe(III)-LVF complexes, providing an efficient and green strategy for contaminant removal during wastewater treatment.

Visible light-induced reduction of ferric iron and activation of persulfate in dissolved organic matter solutions: A green and efficient strategy to enhance fenton-like oxidation

Visible light-induced reduction of ferric iron and activation of persulfate in dissolved organic matter solutions: A green and efficient strategy to enhance fenton-like oxidation

Catalytic Oxidation of Hydroxypropyl Guargum by a Fenton-like reaction

To seek for efficient Fenton-like oxidation processing for the treatment in waste fracturing fluid containing hydroxypropyl guargum under high pH value, a series of o-phenylenediamine(L) metal complex was prepared for the oxidation catalysts. The catalyst was screened by the viscosity reduction of hydroxypropyl guargum solution oxidized by H2O2. The results show that Fe (III)L exhibits high catalytic perform for degradation of hydroxypropyl guargum in a wide pH range 7.0-13.0. The viscosity of hydroxypropyl guar gum can be reduced effectively with the 10.0% H2O2 (mass ratio to hydroxypropyl guar gum) and 10.0% Fe (III)L (mass ratio to H2O2), and the COD value can be decreased to 630 mg/L from 7880 mg/L with enough H2O2, and Fe(III)L also shows great catalytic ability in the degradation of various polymers by H2O2. The proposed mechanism of the activation of H2O2 by the complex was studied by UV spectrum.

Polyvinylpyrrolidone-induced size-dependent catalytic behavior of Fe sites on N-doped carbon substrate and mechanism conversion in Fenton-like oxidation reaction

Fe-based N-doped carbon catalysts (Fe/NC-XPVP) are synthesized through a solvent-free and one-step pyrolysis strategy, allowing for the control of Fe active center sizes and the morphology of carbon substrates. The variable-sized Fe active centers in Fe/NC-XPVP exhibit size-dependent catalytic behavior in peroxymonosulfate (PMS) activation reaction, which indicates that downsizing Fe particles to atomic level achieves performance improvement and mechanism transformation from radical to non-radical pathway. The optimal Fe/NC-1.0PVP catalyst can realize nearly 100.0 % of tetracycline degradation efficiency within 30 min. Density functional theory calculations demonstrate that the strong adsorption of PMS onto Fe-N4 sites can promote the formation of catalyst/PMS* complexes and induce the occurrence of electron transfer process, which performs great resistance to complex water environments during PMS activation. This work gives valuable insights into the precise design and regulation of metal active sites on N-doped carbon materials and provides a promising catalyst for wastewater remediation.

Ion exchange synthesis of copper-based hydroxyapatite for the catalytic degradation of phenol

Abstract Hydroxyapatite (HAP) is a material renowned for its exceptional capabilities in adsorbing and exchanging heavy metal ions, making it a widely employed substance within the environmental domain. This study aims to present a novel material, namely copper–HAP (Cu–HAP), which was synthesized via an ion exchange method. The resulting material underwent comprehensive characterization using scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and Brunauer–Emmett–Teller (BET) analysis. Subsequently, based on the principle of the Fenton-like oxidation reaction, the material was used for the degradation of phenol. The outcomes of the investigation revealed that the optimal preparation conditions for the catalyst were achieved at a temperature of 40 °C, a pH value of 5, and a relative dosage of Cu–HAP at 100 mg/g. Under the reaction conditions of a catalyst dosage of 2 g/L, a 30% hydrogen peroxide concentration of 30 mM, a phenol concentration of 20 mg/L, a pH value of 6, a temperature of 40 °C, and the degradation rate of phenol impressively reached 98.12%. Furthermore, the degradation rate remained at 42.31% even after five consecutive cycles, indicating the promising potential of Cu–HAP in the treatment of recalcitrant organic compounds within this field.

A pilot scale of electrochemical integrated treatment technology and equipment driven by solar energy for decentralized domestic sewage treatment

Based on the natural air diffusion electrode (NADE) cathode, a solar-driven electrochemical integrated sewage treatment technology and equipment in a pilot scale was developed to treat dispersed rural wastewater. The non-aeration NADE had efficient and stable H2O2 production performance, maintaining the H2O2 output between 1474 and 1535 mg h−1 within 50 h with the current efficiency of 77.4%–80.6%. This electrochemical integrated wastewater treatment system was coupled with technologies such as dual-cathode electro-Fenton, peroxi-coagulation and photoelectro-Fenton, which effectively improved the conversion and utilization efficiency of H2O2. It integrated Fenton-like oxidation, electro-oxidation and UV/H2O2, as well as Fe(OH)3-dominated flocculation, which could effectively remove various pollutants in wastewater. The integrated sewage treatment equipment (500 L d−1) realized the effective treatment of a rural decentralized domestic sewage, achieving simultaneous removal of chemical oxygen demand (COD), NH3–N, total phosphorus (TP) and bacteria. Driven by solar energy, its application feasibility, superiority and stability have been proved, providing theoretical and technical support for the efficient and low-consumption treatment of dispersed organic wastewater.

Recycling waste iron-rich algal flocs as cost-effective biochar activator for heterogeneous Fenton-like reaction towards tetracycline degradation: Important role of iron species and moderately defective structures

Harvesting aquatic harmful algal blooms (HABs) and reusing them is a promising way for antibiotic degradation. Herein, a novel iron-rich biochar (Fe-ABC), derived from algal biomass harvested by magnetic coagulation, was successfully designed and fabricated as activator for heterogeneous Fenton-like reaction. The modification methods and pyrolysis temperatures (400–800 °C) were optimized to enhance the formation of rich iron species and moderately defective structure, yielding Fe-ABC-600 with enhanced electron transfer and H2O2 activation capability. Thus, Fe-ABC-600 exhibited superior removal efficiency (95.33%) on tetracycline (TC), where the presence of multiple iron species (Fe3+, Fe2+ and Fe4+) and moderately defective structure accelerating the Fenton-like oxidation. The concentration of leaching Fe after each reaction was all below 0.74 mg/L in five cycles, ensuring the sustained degradation. And •OH was proved to be the major radical contributing to the degradation of TC, as well as the direct electron transfer mechanism together, in which the CO acted as electron regulator and electron donor. Fe-ABC as a cost-effective catalyst has notable application potentials in TC removal from wastewater owing to its remarkable advantages of high resource utilization, enhanced catalytic property, high ecological safe, notable TC degradation efficiency, low cost and environmental-friendliness.

Catalytic Activity of Rare Earth Elements (REEs) in Advanced Oxidation Processes of Wastewater Pollutants: A Review.

In recent years, sewage treatment plants did not effectively remove emerging water pollutants, leaving potential threats to human health and the environment. Advanced oxidation processes (AOPs) have emerged as a promising technology for the treatment of contaminated wastewater, and the addition of catalysts such as heavy metals has been shown to enhance their effectiveness. This review focuses on the use of rare earth elements (REEs) as catalysts in the AOP process for the degradation of organic pollutants. Cerium and La are the most studied REEs, and their mechanism of action is based on the oxygen vacancies and REE ion concentration in the catalysts. Metal oxide surfaces improve the decomposition of hydrogen peroxide to form hydroxide species, which degrade the organics. The review discusses the targets of AOPs, including pharmaceuticals, dyes, and other molecules such as alkaloids, herbicides, and phenols. The current state-of-the-art advances of REEs-based AOPs, including Fenton-like oxidation and photocatalytic oxidation, are also discussed, with an emphasis on their catalytic performance and mechanism. Additionally, factors affecting water chemistry, such as pH, temperature, dissolved oxygen, inorganic species, and natural organic matter, are analyzed. REEs have great potential for enhancing the removal of dangerous organics from aqueous solutions, and further research is needed to explore the photoFenton-like activity of REEs and their ideal implementation for wastewater treatment.

Peroxydisulfate activation using magnetic graphite intercalation compounds: A promising system for pharmaceuticals removal in treated wastewater matrix

The release of contaminants of emerging concern (CECs) from the effluents of municipal wastewater treatment plants (MWWTPs) into the environment is a major problem because of its influence on both the environment and human health. The Fenton system has been demonstrated to remove CECs from different aqueous matrices effectively. However, the Fenton system has been considered to be efficient at acidic pH, which hinders its application in MWWTPs. Herein, the Fenton-like oxidation catalyzed by iron species intercalated between carbon layers of graphite (as a recyclable catalyst) was studied to remove amoxicillin, as a model pharmaceutical, from effluents of MWWTPs. Response surface methodology (RSM) was used to optimize system parameters, including catalyst loading, peroxydisulfate (PDS) dosage, and reaction time. Amoxicillin removal in the proposed system reached more than 99% by utilizing a catalyst dosage of 2 g/L and 5 mM of PDS at neutral pH. Sensitivity analysis of model parameters indicated that the amoxicillin removal was highly sensitive to the dosage of the catalyst, while the model is less sensitive to PDS dosage and reaction time. The results indicated that the PDS activation employing magnetic graphite intercalation compounds could be used as a promising system for pharmaceutical removal from MWWTP effluents.

Optimization of iron-ZIF-8 catalysts for degradation of tartrazine in water by Fenton-like reaction

Optimization of iron zeolitic imidazole framework-8 (FeZIF-8) nanoparticles, as heterogeneous catalysts, were synthesized and evaluated by the Fenton-like reaction for to degrade tartrazine (Tar) in aqueous environment. To achieve this, ZIF-8 nanoparticles were modified with different iron species (Fe2+ or Fe3O4), and subsequently assessed through the Fenton-like oxidation. The effect of different parameters such as the concentration of hydrogen peroxide, the mass of catalyst and the contact time of reaction on the degradation of Tar by Fenton-like oxidation was studied by using the Box-Behnken design (BBD). The BBD model indicated that the optimum catalytic conditions for Fenton-like reaction with an initial pollutant concentration of 30 ppm at pH 3.0 were T = 40 °C and 12 mM of H2O2, 2 g/L of catalyst and 4 h of reaction. The maximum Tar conversion value achieved with the best catalyst, Fe1ZIF-8, was 66.5% with high mineralization (in terms of decrease of total organic carbon – TOC), 44.2%. To assess phytotoxicity, the germination success of corn kernels was used as an indicator in the laboratory. The results show that the catalytic oxidation by Fenton-like reaction using heterogeneous iron ZIF-8 catalysts is a viable alternative for treating contaminated effluents with organic pollutants and highlighted the importance of the validation of the optimized experimental conditions by mathematical models.

Fe-zeolites for the adsorption and oxidative degradation of nitroaromatic compounds in water

Nitroaromatic compounds (NACs) are prominent explosives. In this context, these toxic substances were released into the environment and cause long-lasting groundwater contamination. In preparation of a possible in-situ remediation, colloidal Fe-zeolites were investigated for their capabilities as adsorbents and oxidation catalysts. It was shown that the Fe-zeolites FeBEA35 and FeFAU55 are potent inorganic adsorbents for NACs and simultaneously capable of activating H2O2 as Fenton-like oxidation catalysts. Adsorption isotherms of 15 NACs on both zeolites were measured to evaluate the option of coupling adsorptive contaminant enrichment with oxidative degradation. The faujasite-type zeolite FeFAU55 showed a distinct S-type adsorption behaviour and reached significantly higher NAC loadings of > 20 wt%. For FeBEA35, L-type adsorption isotherms and maximum loadings qmax of about 4 wt% were obtained. Degradation of all NACs, monitored by nitrate formation, was observed. Apparent rate constants of the NACs with hydroxyl radicals in a homogeneous, stoichiometric Fenton reaction were related to the heterogeneous system to examine the role of adsorption on the oxidative degradation. Beneficial influence of the adsorption on the oxidation rates was identified. The results of this work open up promising prospects for future application of Fe-zeolites for the in-situ remediation of NAC-contaminated groundwater.