Heterogeneous Fenton Reaction Research Articles

Fe-supported perlite applied for the degradation of Rhodamine B dye by Heterogeneous Fenton reaction

This study aimed to evaluate a technique of Fe ion impregnation on perlite mineral and assess its behavior in a heterogeneous Fenton-like reaction, at room temperature and under acidic and alkaline conditions in the removal of Rhodamine B dye. For the catalyst preparation, a suspension of heptahydrated ferrous sulfate (FeSO4.7H2O) was used, followed by thermal treatment (calcination). Different doses of H2O2 (35% v/v) were applied to evaluate dye removal rates. Fe leaching in reaction media was analyzed. Rhodamine B removal at pH 4, 7, 9, 10, and 11 had the respective removal rates of 99.8%, 57.4%, 73.1%, 77.5%, and 96.9% in 240 minutes of reaction. At pH 12, there was 99.7% removal in 110 minutes of reaction. Reactions performed with low dosages of hydrogen peroxide showed, at pH 4 and 11, removal percentages of 95.8% and 90.2%, respectively, in 150 minutes of reaction. Under the same conditions, at pH 12, the removal percentage was 98.6% in 105 minutes. The synthesized catalyst exhibited satisfactory activity under acidic and alkaline conditions, for three cycles, showing promise for applications in heterogeneous Fenton reactions on a large scale.

Methods and Prospects for Enhancing Heterogeneous Fenton Catalytic Activity

AbstractAs an advanced oxidation process that can efficiently remove organic pollutants in water, Fenton oxidation has attracted much attention in recent years. Compared to homogeneous Fenton, it has a wider applicability, a wide pH range, higher degradation efficiency, lower environmental impact, and lower treatment cost. However, the heterogeneous Fenton reaction also has some limitations, such as the deactivation of the catalyst, the reaction rate being limited by the solid–liquid interface mass transfer. Therefore, the development of efficient and stable heterogeneous Fenton catalytic system is the focus of Fenton reaction research at present. In this paper, the research of heterogeneous Fenton catalysis are introduced, and the construction characteristics and catalytic mechanism of iron base, copper base, transition metals and their oxides, chelating agents, carbon materials, supported catalysts, and photocatalysis are systematically summarized. In addition, the strategies for the formation of FeII and the promotion of H2O2 decomposition were discussed, and the mechanism and pathway of the heterogeneous Fenton catalyst for the efficient degradation of organic matter were summarized in order to provide technical support for further research on heterogeneous Fenton catalysts.

Expanding the pH range of Fenton-like reactions for pollutant degradation: The impact of acidic microenvironments

Heterogeneous Fenton reactions offer the opportunities to overcome iron sludge accumulation and limited recyclability of existing homogeneous Fenton process, but the sharp attenuation in their reactivity at near-neutral and even higher pH conditions, still remains a formidable challenge. In this work, we report a versatile and robust approach to create a local acidic microenvironment on BiOI with graphene oxide bonding, enabling the heterogeneous Fenton (BiOI@rGO/H2O2) system to sustainably degrade organic pollutants over a wide pH range (3.0-10.0). Notably, BiOI@rGO exhibits a superior catalytic activity (∼100% removal) and robust durability (over ten cycles) in degrading bisphenol A and tetracycline, even in real wastewater scenarios. Furthermore, immobilizing the BiOI@rGO on carbon felt to establish a continuous flow-through device achieves a stable treatment performance with a degradation efficiency exceeding 98% for micropollutants over a continuous operation. This work provides a paradigm for constructing an acidic microenvironment on the catalyst to surmount the pH limitations of the heterogeneous Fenton reactions for advanced water purification.

Bridging oxygen mediated alkaline Fenton catalysis in LDHs for water purification

In this study, we fabricate a non-redox layered double hydroxides (CuFe-LDHs) catalyst to realize Fenton catalysis under alkaline conditions. The electronic structure of bridging oxygen atoms (OB) is optimized via hybridizing with Cu2+ and Fe3+ for fast dehydrogenation and recombination of hydrogen peroxide (H2O2) without the influence of -OH. Experimental results confirm that the moderate p-band center of OB and the strong interlayer force enhance H2O2 activation from thermodynamic and kinetic perspectives, respectively. The required free energy of the rate-determining step decreases from 1.78 eV to 1.06 eV. The CuFe-LDHs/H2O2 system demonstrates extraordinary treatment performance for alkaline organic wastewater. The continuous flow reactor experiment achieves long-term stability (up to 12 h), confirming the potential of CuFe-LDHs in practical applications. This study enriches the H2O2 activation mechanism over nonmetallic sites and provides the theoretical and feasible basis for the practical application of heterogeneous Fenton reactions.

Enhanced Photo-Fenton Degradation of Antibiotics through Internal Electric Field Formation at the Interface of Mixed-Phase FeS₂

Article Enhanced Photo-Fenton Degradation of Antibiotics through Internal Electric Field Formation at the Interface of Mixed-Phase FeS₂ Hongyan Liu 1,2, Yunhang Shao 1,2, Shuai Dou 1,2 and Chengsi Pan 1,2,* 1 Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China 2 International Joint Research Center for Photoresponsive Molecules and Materials, Jiangnan University, Wuxi 214122, China * Correspondence: cspan@jiangnan.edu.cn Received: 9 September 2024; Revised: 9 October 2024; Accepted: 13 November 2024; Published: 15 November 2024 Abstract: Iron sulfide (FeS₂) is a rich mineral resource widely used as an efficient Fenton and photo-Fenton reagent due to its non-toxicity and low synthesis cost. However, the mechanism underlying its photo-Fenton degradation activity related to the two crystal phases—pyrite (P-FeS₂) and marcasite (M-FeS₂)—is still not well understood. In this study, P-FeS₂, M-FeS₂, and their mixed phase (P/M-FeS₂) were prepared through hydrothermal reactions. The results showed that P/M-FeS₂ exhibited the highest photo-Fenton degradation activity, achieving a removal rate of approximately 99% for 50 ppm of ciprofloxacin (CIP) within 3 minutes, outperforming other photo-Fenton catalysts in pollutant degradation. The study revealed that an internal electric field (IEF) is generated at the interface of M-FeS₂ and P-FeS₂ due to their differing work functions. This IEF accelerates the regeneration of the active sites (Fe²⁺ in S₂²⁻-P-FeS₂ and M-FeS₂) required for the Fenton reaction, thereby explaining the superior activity of the P/M-FeS₂ mixed phase. This study introduces the IEF theory for the first time to explain the mechanism of mixed-phase catalysts in the photo-Fenton reaction. The formation of IEF can enhance the regeneration of the active sites involved in the Fenton reaction, thereby improving both reaction activity and stability. This work highlights the significance of regulating crystal phases in the degradation of pollutants during heterogeneous Fenton reactions and offers insights for developing highly efficient Fenton catalysts.

Removal of Methylene Blue from Aqueous Solution through Adsorption and Heterogeneous Fenton Reaction using Iron Oxides Produced by Different Methods

Direct discharge of industrial wastewater containing dyes into water bodies has contributed to the scarcity of drinking water. As environmental legislation becomes stricter, it is increasingly important to develop efficient methods for wastewater treatment. Traditional methods are commonly costly and have limited efficiency. This study aimed to prepare iron oxides via different synthetic routes and evaluate the effect of synthesis method on the efficiency of these materials as adsorbents and heterogeneous Fenton catalysts for the removal of methylene blue from aqueous solution. Iron oxides were synthesized by non-hydrolytic sol–gel (NHSG) and co-precipitation (CP) methods, followed by hydrothermal treatment for different times. CP oxides demonstrated high efficiency in dye adsorption, particularly the sample subjected to hydrothermal treatment for 6 h (CP-R6). This sample achieved 94.04% removal in 120 min. NHSG materials, by contrast, were less effective. The CP series of materials showed superior catalytic performance in heterogeneous Fenton experiments, with CP-R6 reaching 98.79% decolorization in 240 min. X-ray diffraction analysis indicated that iron oxides were composed of crystalline hematite and maghemite. Scanning electron microscopy revealed that CP materials were more porous and homogeneous than NHSG materials. The results demonstrated the efficiency of the developed iron oxides in removing methylene blue via adsorption and heterogeneous Fenton degradation and clarified how synthesis method influences adsorptive and catalytic properties.

A crystallinity control strategy for controllable Heterogeneous-Homogeneous reaction and catalytic performance in wet-mechanochemical synthesized FeS2 Fenton system

In heterogeneous Fenton system, the Heterogeneous-Homogeneous reaction type induced by surface-bonded or dissolved catalytic center plays a vital role in determining Fenton performance. However, how to directionally control the reaction type with facile method still remains challenging. Herein, a novel crystallinity control strategy based on wet-mechanochemical synthesis combined with heat-treatment was applied to synthesize FeS2 nanoparticles with different crystallinity. The different crystalline FeS2 based Fenton system exhibited superior sulfamethoxazole removal performance at wide pH range (5.6–11) with •OH as dominating reactive oxygen species. The relative degradation contribution of homogeneous and heterogeneous Fenton reaction was semi-quantitatively evaluated, and the relationship between crystallinity indexes of FeS2 and degradation kinetic constants was established. It’s found that FeS2 crystallinity was directly correlated with its degradation efficiency, which first increased and then declined with crystallinity increasing. Crystallinity control strategy effectively determined dominating reaction type (homogeneous or heterogeneous) and further regulated catalytic performance in FeS2 Fenton system based on the interaction of specific surface area and Fe2+ dissolution ability. This work provides a novel crystallinity control strategy to build a correlative bridge among crystallinity, dominating reaction type and catalytic performance in FeS2 Fenton system.

Enhancing the Fenton catalytic activity of Fe-MOFs by incorporation of carbon nanotubes: The crucial role of C-O-Fe coordination structure

Fe-based metal–organic frameworks (MOFs) have garnered significant attention as catalysts for heterogeneous Fenton reactions, while the limited efficiency of the Fe(III)/Fe(II) redox cycle hinders their widespread use in wastewater treatment. Herein, we successfully incorporated carbon nanotubes (CNTs) into MIL-101(Fe) to modulate the coordination environment of Fe for achieving better catalytic activity. The MIL-101(Fe)/CNTs/H2O2 system shows outstanding performance in degrading various pollutants, with the catalytic activity of the MIL-101(Fe)/CNTs composites (98.8%) significantly surpassing that of MIL-101(Fe) alone (26.4%) or CNTs alone (3.5%). Multiple experimental findings suggest that this synergistic effect is primarily attributed to the C-O-Fe bridge bonds resulting from the interaction of surface carboxyl groups on CNTs with Fe in MIL-101(Fe). This unique coordination structure accelerates the redox cycle of Fe(III)/Fe(II), thereby promoting the generation of hydroxyl radicals (HO•). Furthermore, the MIL-101(Fe)/CNTs composites demonstrate excellent reusability and stability, maintaining effectiveness over a wide pH range from 3.0 to 6.5. This study provides new insights into regulating the microstructure of Fe-based MOFs to enhance their Fenton catalytic activity.

The Construction of Iodine-Doped Carbon Nitride as a Metal-Free Nanozyme for Antibacterial and Water Treatment.

Metal-free photocatalysis that produces reactive oxygen species (ROS) shows significant promising applications for environmental remediation. Herein, we constructed iodine-doped carbon nitride (I-CN) for applications in the photocatalytic inactivation of bacteria and the heterogeneous Fenton reaction. Our findings revealed that I-CN demonstrates superior photocatalytic activity compared to pure CN, due to enhanced light adsorption and a narrowed band gap. Antibacterial tests confirmed that I-CN exhibits exceptional antibacterial activity against both Escherichia coli and Staphylococcus aureus. The results showed that I-CN effectively generates superoxide radicals and hydroxyl radicals under light irradiation, resulting in enhanced antibacterial activity. In addition, I-CN can also be applied for a heterogeneous photo-Fenton-like reaction, achieving a high performance for the degradation of sulfamethoxazole (SMX), a typical antibiotic, via the photocatalytic activation of peroxymonosulfate (PMS). These results shed new light on the fabrication of metal-free nanozymes and their applications for disinfection and water decontamination.

Boosted photo-Fenton-like process for selective degradation of emerging contaminants by dehydrated Fe-based metal–organic framework with thermodynamically-favorable center metal electron density and confinement effect

The Heterogeneous Fenton reaction has long stood out as a highly effective technology for water purification. However, it is nowadays facing challenges such as low selectivity, sluggish Fe(III) reduction, and limited H2O2 conversion efficiency. Herein, dehydrated MIL-100(Fe)-250 was synthesized through thermal treatment, demonstrating superior efficiency in removing emerging contaminants, with a three-fold efficiency higher than undehydrated sample. The dehydrated MIL-100(Fe)-250 exhibited selective acceleration in the removal of quinolones and phenolic organics, rendering the system resistant to interference from coexisting matter. Through in-situ diffuse reflectance infrared Fourier-transform spectroscopy and density functional theory calculation, it was manifested that dehydration process regulates the steric hindrance and local electron density of Fe ions. This adjustment enhances charge transfer, thereby facilitating Fe(III) reduction and promoting the H2O2 activation and conversion efficiency. Moreover, the quasi-steady-state concentrations of hydroxyl radical in MIL-100(Fe)-250 were found to be 2.2 times higher than that those in undehydrated sample. Impressively, the dehydrated MIL-100(Fe)-250 displayed adaptability across a broad pH range of 5.0–9.0. The present study underscores the significant potential of porous MIL-100(Fe)-250 with spatial confinement, which imparts a clear size exclusion effect. As a result, this catalyst emerges as a promising candidate for eliminating contaminants in real water matrices, offering a viable strategy for water pollution control.

Study of catalytic properties and grinding performance of single-crystal SiC heterogeneous Fenton reaction grinding discs

Study of catalytic properties and grinding performance of single-crystal SiC heterogeneous Fenton reaction grinding discs

Magnetite-driven Bio-Fenton degradation of chloroacetanilide herbicides by a newly isolated hydrogen peroxide producing bacterium Desemzia sp. strain C1

The efficiency of the Fenton reaction is markedly contingent upon the operational pH related to iron solubility. Therefore, a heterogeneous Fenton reaction has been developed to function at neutral pH. In the present study, the Bio-Fenton reaction was carried out using magnetite (Fe(II)Fe(III)2O4) and H2O2 generated by a newly isolated H2O2-producing bacterium, Desemzia sp. strain C1 at pH 6.8 to degrade chloroacetanilide herbicides. The optimal conditions for an efficient Bio-Fenton reaction were 10 mM of lactate, 0.5% (w/v) of magnetite, and resting-cells (O.D.600 = 1) of strain C1. During the Bio-Fenton reaction, 1.8–2.0 mM of H2O2 was generated by strain C1 and promptly consumed by the Fenton reaction with magnetite, maintaining stable pH conditions. Approximately, 40–50% of the herbicides underwent oxidation through non-specific reactions of •OH, leading to dealkylation, dechlorination, and hydroxylation via hydrogen atom abstraction. These findings will contribute to advancing the Bio-Fenton system for non-specific oxidative degradation of diverse organic pollutants under in-situ environmental conditions with bacteria producing high amount of H2O2 and magnetite under a neutral pH condition.

Preparation of novel Fe-containing zeolite-A for KN-R decolorization by Fenton-like reaction.

Herein, novel catalysts of Fe-containing zeolite-A (Fe/zeolite-A) were synthesized by exchanging iron ions into zeolite-A framework, and short-chain organic acids (SCOAs) were employed as chelating agents. Reactive Brilliant Blue KN-R (KN-R) was used as a model pollutant to evaluate the performance of these catalysts based on the heterogeneous Fenton reaction. The results showed that Fe-OA/3A, which applied zeolite-3A as the supporter and oxalic as the chelating agent, presented the most prominent KN-R decolorization efficiency. Under the initial pH of 2.5, 0.4 mM KN-R could be totally decolorized within 20 min. However, the mineralization efficiency of KN-R was only 58.2%. Therefore, anthraquinone dyes were introduced to modify zeolite-3A. As a result, the mineralization efficiency of KN-R was elevated to 92.7% when using Alizarin Violet (AV) as the modifier. Moreover, the modified catalysts exhibited excellent stability, the KN-R decolorization efficiency could be maintained above 95.0% within 20 min after operating for nine cycles. The mechanism revealed that the Fe(II)/Fe(III) cycle was accelerated by AV-modified catalyst thus prompting the KN-R decolorization in Fenton-like system. These findings provide new insights for preparing catalysts with excellent activity and stability for dye wastewater treatment.

Continuous Heterogeneous Fenton for Swine Wastewater Treatment: Converting an Industry Waste into a Wastewater Treatment Material

Swine wastewater (SW) was treated using industrial wastes as raw materials in a pre-treatment process (coagulation or adsorption), followed by a continuous heterogeneous Fenton reaction. Before the treatment conducted as a continuous operation, two different batch optimization strategies were evaluated, in which the effects of H2O2 concentration and pH were studied. The results show that using excessive H2O2 results in the same behavior, regardless of whether the pH is 3 or 7.5, while at low H2O2 concentrations, the acidic pH improves the chemical oxygen demand (COD) removal due to a higher solubility of iron. The partial addition of H2O2 after 60 min of the reaction proved to be unbeneficial. Considering other perspectives, a continuous Fenton process using iron filings (IF) as the iron source ([H2O2] = 50 mg/L) was applied after the SW pre-treatment, consisting of adsorption with red mud (RM) or coagulation with poly-diallyldimethylammonium chloride (PDADMAC). The RM adsorption presented higher COD removal and lower toxicity than the PDADMAC coagulation, revealing to be a suitable material for this purpose, but for both pre-treatments, the application of a subsequent continuous Fenton process revealed to be essential to achieve the COD discharge limits imposed by the Portuguese law. In addition, high amounts of dissolved iron were present in the samples (55–58 mg/L) after the Fenton process. However, after the overall treatment, the samples showed no harmful characteristics for Lepidium sativum, being classified as “non-toxic”, contrary to the initial wastewater.

Highly Efficient Removal of Chromium, Methylene Blue and Methyl Orange Using Electrospun Polyurethane as a Support in Heterogeneous Fenton Reaction

Highly Efficient Removal of Chromium, Methylene Blue and Methyl Orange Using Electrospun Polyurethane as a Support in Heterogeneous Fenton Reaction

Nanoconfinement-triggered oligomerization pathway for efficient removal of phenolic pollutants via a Fenton-like reaction

Heterogeneous Fenton reaction represents one of the most reliable technologies to ensure water safety, but is currently challenged by the sluggish Fe(III) reduction, excessive input of chemicals for organic mineralization, and undesirable carbon emission. Current endeavors to improve the catalytic performance of Fenton reaction are mostly focused on how to accelerate Fe(III) reduction, while the pollutant degradation step is habitually overlooked. Here, we report a nanoconfinement strategy by using graphene aerogel (GA) to support UiO-66-NH2-(Zr) binding atomic Fe(III), which alters the carbon transfer route during phenol removal from kinetically favored ring-opening route to thermodynamically favored oligomerization route. GA nanoconfinement favors the Fe(III) reduction by enriching the reductive intermediates and allows much faster phenol removal than the unconfined analog (by 208 times in terms of first-order rate constant) and highly efficient removal of total organic carbon, i.e., 92.2 ± 3.7% versus 3.6 ± 0.3% in 60 min. Moreover, this oligomerization route reduces the oxidant consumption for phenol removal by more than 95% and carbon emission by 77.9%, compared to the mineralization route in homogeneous Fe2++H2O2 system. Our findings may upgrade the regulatory toolkit for Fenton reactions and provide an alternative carbon transfer route for the removal of aqueous pollutants.

A Procedure for Rational Probe Liquids Selection to Determine Hansen Solubility Parameters

AbstractHansen Solubility Parameters (HSP), viewed in the context of similarity whenever dispersion is focused, offer valuable insights into the surface characteristics of nanoparticles. However, existing methods for determining HSP via the sedimentation of nanoparticles require multiple probe liquids, resulting in time‐consuming, costly experiments with potential health risks. To address this, we developed a two‐step strategy that enables a systematic selection of liquids. The key element of the approach is to first identify the rough location of the Hansen sphere in the three‐dimensional Hansen space using a well‐chosen set of probe liquids of different polarities and chemical structures. Then, depending on the outcome of the first step, a particular choice of liquids is made for the final HSP determination. Taken together, the introduced procedure reduces the amount of required liquids for experiments from currently more than ten to a maximum of seven chosen based on a well‐defined, coherent methodology. Validation was performed on carbon black, non‐pigmentary nano‐scale titania, silicon/carbon composites, and lanthanum cobaltite particles, i. e., relevant materials that are commonly utilized in fuel cells, batteries, cyclohexene oxidation, catalytic combustion, photocatalysis, and heterogeneous Fenton reactions. The study showcases the potential to save time, costs, and efficiently determine HSP values in a comparable manner.

Theoretical study of p-block metal-nitrogen-carbon single-atom catalysts for heterogeneous Fenton-like reaction

Heterogeneous Fenton reaction has been widely used in water purification and environmental remediation due to the highly reactive nature of hydroxyl radicals. Nevertheless, the intrinsic structure-activity relationship for heterogeneous Fenton...

Heteroatom-doped carbon nanomaterials as potential heterogeneous Fenton reaction catalysts

A volcano relationship between the catalytic activity and the adsorption energies of reaction intermediates was found for the H2O2 dissociation on heteroatom-doped carbon nanomaterials.

Comparative Study of Organics Removal from Refinery Wastewater by Photocatalytic Fenton Reaction Coupled with Visible Light and Ultraviolet Irradiation

The study investigates photocatalytic advanced oxidation processes using iron-doped zeolite catalysts in heterogeneous Fenton reactions to degrade organic contents as chemical oxygen demand. The research revealed that the heterogenous photocatalytic Fenton process was the most successful treatment method under acidic circumstances and generated a greater rate of chemical oxygen demand degradation in a concise amount of radiation time. Compared to the heterogenous Fenton process with ultraviolet irradiation, it increased oxidation and was affected by catalyst load, power of hydrogen pH, hydrogen peroxide amounts, and temperature. The findings showed that the iron-doped zeolite catalyst, pH, and temperature significantly degraded the chemical oxygen demand. The experiment determined that the optimal conditions were obtained at a catalyst load of 0.07 g, pH of 3, with 20% excess of hydrogen peroxide, 40 °C in 2 hours for the ultraviolet/ iron-doped zeolite/hydrogen peroxide system that gave 99.84 % of the removal of the chemical oxygen demand. The heterogeneous photocatalytic Fenton method accompanied the reactions by hydroxyl radical production, which quickly reached its maximal reduction.