Heterogeneous Fenton Reaction Research Articles

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.

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.

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.

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.

Novel heterogeneous Fenton catalysts for promoting carbon iron electron transfer by one-step hydrothermal synthesization

Carbon materials play a crucial role in promoting the Fe(III)/Fe(II) redox cycle in heterogeneous Fenton reactions. However, the electron transfer efficiency between carbon and iron is typically low. In this study, we prepared a novel heterogeneous Fenton catalyst, humboldtine/hydrothermal carbon (Hum/HTC), using a one-step hydrothermal method and achieved about 100 % reduction in Fe(III) during synthesis. Moreover, the HTC continuously provided electrons to promote Fe(II) regeneration during the Fenton reaction. Electron paramagnetic resonance (EPR) and quenching experiments showed that Hum/HTC completely oxidized As(III) to As(V) via free radical and non-free radical pathways. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) and two-dimensional correlation spectroscopy (2D-COS) analyses revealed that monodentate mononuclear (MM) and bidentate binuclear (BB) structures were the dominant bonding methods for As(V) immobilization. 40 %Hum/HTC exhibited a maximum As(III) adsorption capacity of 167 mg/g, which was higher than that of most reported adsorbents. This study provides a novel strategy for the efficient reduction of Fe(III) during catalyst synthesis and demonstrates that HTC can continuously accelerate Fe(II) regeneration in heterogeneous Fenton reactions.

Preparation of Fenton Catalysts for Water Treatment

In the heterogeneous Fenton reaction, a solid catalyst reacts with H2O2 to generate highly oxidizing free radicals, that degrade organic pollutants in aqueous solutions. In this study, impregnation calcination was used to modify activated carbon and load it with various metal compounds. The synergistic catalysis of the various metal compounds showed improved catalytic activity, and the prepared heterogeneous Fenton catalyst exhibited high catalytic activity, a wide pH range, and good stability. The concentration ratios of the Fenton catalyst impregnation solutions-were as follows: Fe3+, Cu2+, Mn2+, and Ce3+ at 0.45, 0.72, 0.19, and 0.11 mol/L, respectively. The optimal sintering temperature of AC impregnation was determined through TGA/DSC, SEM, SEM-EDS, XPS, and XRD testing. At a final calcination temperature of 900 °C, the degradation efficiency of 10 ppm methylene blue reached 98.25% at pH 5 with 5 mM H2O2. After ten soaking cycles, the degradation efficiency exceeded 90%. The structure and performance of the catalysts were characterized using EPR, BET, ICP, and UV spectroscopy, demonstrating the excellent performance of the catalyst and providing an improved treatment plan for solving wastewater problems.

Subnanoscale spatially confined heterogeneous Fenton reaction enables mineralization of perfluorooctanoic acid

Superoxide radical (•O2−) is capable of degrading perfluorinated compounds that are persistent in nature and cannot be removed by biological or advanced oxidation treatments, but the inherent drawback is the negligible reactivity of •O2−in aqueous phases due to the hydration effect. Here, we explored an innovative way to make use of •O2− by modulating a partial hydration state through spatial confinement control. We demonstrated this idea by conducting heterogeneous Fenton reaction with layered iron oxychloride (FeOCl) catalyst, wherein •O2−radicals produced and confined within the catalyst structure (interlayer spacing of 7.92 Å) showed defluorination effect dealing with perfluorooctanoic acid (PFOA) as model compound. The defluorination combined with advanced oxidation achieved mineralization. Mechanism study revealed that the confinement frustrated the hydration shell of •O2−with coordination number reduced from 3.3 (for bulk phase) to 1.89, and thereby changed its orbital electron properties and enhanced the nucleophilic ability. We further demonstrated a compact FeOCl membrane reactor with highly efficient degradation of PFOA (kobs up to 1.2 min−1) and cost-effective mineralization (2 × 10−6 $ per mgC), operated under ultrafiltration reaction mode. Our findings highlight the great interest of developing spatial confinement technology to modulate •O2−-based reactions, as well as the feasibility of combining confinement catalyst structures with heterogeneous Fenton reaction to achieve the mineralization treatment goal.

Efficient degradation of methyl orange by heterogeneous Fenton reaction using modified bentonite by a simple method

Efficient degradation of methyl orange by heterogeneous Fenton reaction using modified bentonite by a simple method

Sustainable reuse of toxic spent granular activated carbon by heterogeneous fenton reaction intensified by temperature changes

A common strategy for removing highly toxic organic compounds, such as chlorinated organic compounds, is their adsorption on granular activated carbon. Spent granular activated carbon results in a toxic residue to manage; therefore, the regeneration and reuse of granular activated carbon on the site would be advisable. This work studies the regeneration of a granular activated carbon saturated in 1,2,4-trichlorobenzene, chosen as the model chlorinated organic compounds, by heterogeneous Fenton, where iron was previously immobilised on the granular activated carbon surface. This methodology avoids the addition of iron to the aqueous phase at concentrations above the allowable limits and the need for acidification. Three successive cycles of adsorption-regeneration were carried out batchwise (5 gGAC·L−1) with a granular activated carbon saturated with 300 mg124-TCB·gGAC−1. The recovery of the adsorption capacity after regeneration was studied with H2O2 (166 mM, 1.5 the stoichiometric dosage), at different concentrations adsorbed with iron adsorbed concentrations (0–12 mgFe·gGAC−1) and temperatures (20–80 °C). Stable recovery of the adsorption capacity values of 65% were obtained at 180 min with 12 mgFe·gGAC−1 and 60 °C. The porosity and surface chemistry of the adsorbent remained very similar after different adsorption-regeneration cycles without iron leaching into the aqueous phase. The oxidant consumption was close to the stoichiometric value for the mineralization of 1,2,4−trichlorobenzene, with a low unproductive consumption of H2O2 with granular activated carbon. In addition, no aromatic or chlorinated by-products were detected in the aqueous solution obtained in the regeneration process. The negligible toxicity of the aqueous phase with the Microtox bioassay confirmed the absence of toxic oxidation by-products.

Tri-modified ferric alginate gel with high regenerative properties catalysts for efficient degradation of rhodamine B

Water pollution caused by dyes has become a focal point of attention. Among them, the heterogeneous Fenton reaction has emerged as an effective solution to this problem. In this study, we designed a ferric alginate gel (PAGM) tri-modified with poly(vinyl alcohol), graphene oxide, and MoS2 as a heterogeneous Fenton catalyst for organic dye degradation. PAGM addresses the drawbacks of alginate gel, such as poor mechanical properties and gel chain dissolution, thereby significantly extending the catalyst's lifespan. The removal rate of rhodamine B by PAGM reached 95.5 % within 15 min, which was 5.9 times higher than that of unmodified ferric alginate gel. Furthermore, due to the π–π interactions, PAGM exhibits unique adsorption properties for pollutants containing benzene rings. Additionally, PAGM can be regenerated multiple times through a simple soaking procedure without any performance degradation. Finally, the reaction column constructed with PAGM maintained an 83.5 % removal rate even after 319 h of continuous wastewater treatment. This work introduces a novel concept for the study of alginate-based gel catalysts in heterogeneous Fenton reactions.

Nitrogen-doped CNTs enhance heterogeneous Fenton reaction for IOH removal by FeOCl: Role of NCNTs and mechanism

Heterogeneous Fenton has already been usedextensively to remove emerging contaminants, however, sluggish Fe(III)/Fe(II) circulation and high mass-transport resistance are its two major limitations. In this study, a novel heterogeneous N-doped carbon nanotubes loaded nano-FeOCl (NCF) catalyst was synthesized by partial thermal decomposition to enhance its catalytic performance. By incorporating NCNTs, the specific surface area of NCF was significantly increased in comparisontoFeOCl, which promotes the accumulation of contaminants on the catalyst surface. Similarly, the degradation rate constant (k) of IOH in the NCF/H2O2 system was observed 114 times greater than that of the FeOCl/H2O2 system. Besides not significantly increased k, excessive H2O2 substantially reduced H2O2 utilization. Electron paramagnetic resonance and electrochemical analysis reflected that the NCNTs facilitated the Fe(III)/Fe(II) circulation by improving electron transfer and enhanced •OH, O2•− and 1O2 availability by exerting a confinement effect. The major reactions assumed in IOH degradation include hydrogen atom abstract, amide hydrolysis, deiodination reaction, •OH radical adduct formation, and oxidation of C-OH. This study elucidates the degradation mechanism of IOH in the heterogeneous Fenton system with carbon-based co-catalysts and provides an efficient measure for removing emerging contaminants from the environment.

The space-charge region at NiFe-MOF⊆LDH p-n junction by self-sacrificing LDH to boost oxygen evolution tandem with in-situ electro-Fenton

The rational design of p-n heterojunction was highly desirable to optimize charge distribution at space-charge region, tailoring the adsorption free energy of intermediate matters, and to boost the oxygen evolution reaction (OER) and in situ electro-Fenton (EF) reaction. Herein, a self-sacrificing strategy has been employed to construct the NiFe-MOF⊆LDH nanosheet arrays on carbon cloth (CC), directly using NiFe-LDH as template. NiFe-MOF⊆LDH exhibited outperformed OER activity with a lower overpotential of 196 mV and smaller Tafel slope of 48 mV dec-1(η10). The conferred higher valence state for Ni3+ and the more carrier density to absorb more OH– ions confirmed by in-situ Raman and density functional theory (DFT) calculation endowed the excellent OER activity, which was expected to endow the self-oxygenation to support the following EF in this system without additional O2. An electrochemical flow reactor was designed for anodic OER and cathodic EF only at low voltage of 1.6 V. Typically, the in-situ H2O2 yield rate could achieve 27.4 mmol/h at cathodic ORR reaction, which was further activated by Fe2+/Fe3+ cycling for the heterogeneous Fenton reaction. This tandem reactor could remove 96% of ibuprofen (IBF) within 120 min with long-term cycle use. In a word, coupling the OER with EF in a flow reactor has possible application in the fields of sustainable energy and environmental remediation.

Heterogeneous Fenton water purification catalyzed by iron phosphide (FeP).

Heterogeneous Fenton reaction has a great application potential in water purification, but efficient catalysts are still lacking. Iron phosphide (FeP) has a higher activity than the conventional Fe-based catalysts for Fenton reactions, but its ability as a Fenton catalyst to directly activate H2O2 remains unreported. Herein, we demonstrate that the fabricated FeP has a lower electron transfer resistance than the typical conventional Fe-based catalysts, i.e., Fe2O3, Fe3O4, and FeOOH, and thus could active H2O2 to produce hydroxyl radicals more efficiently. In the heterogeneous Fenton reactions for sodium benzoate degradation, the FeP catalyst presents a superior activity with a reaction rate constant more than 20 times those of the other catalysts (i.e., Fe2O3, Fe3O4, and FeOOH). Moreover, it also exhibits a great catalytic activity in the treatment of real water samples and has a good stability in the cycling tests. Furthermore, the FeP could be loaded onto a centimeter-sized porous carbon support and the prepared macro-sized catalyst exhibits an excellent water treatment performance and can be well recycled. This work reveals a great potential of FeP as a catalyst for heterogeneous Fenton reactions and may inspire further development and practical application of highly efficient catalysts for water purification.

Heterogeneous Fenton treatment of actual textile and dyeing wastewater by α-Cu-FeOOH nanomaterial

This work reports the successful synthesis and application of α-Cu-FeOOH in heterogeneous Fenton treatment of actual textile dyeing wastewater. The material characteristics were analyzed by SEM, EDX, BET, FTIR, and XRD methods. In heterogeneous Fenton tests, the highest TOC and color removal efficiencies were found to be 46.88 and 37.98%, respectively, in the suitable conditions of Cu/Fe molar ratio = 5%, [H2O2] = 0.1 M, [α-Cu-FeOOH] = 0.6 g/L, pH = 7, and after 60 min. The values of color and TOC after treatment well met the discharge standard for textile dyeing wastewater (QCVN 13:2015/BTNMT, Column B). The presence of copper in the material enhanced the activation of H2O2 in heterogeneous Fenton reactions under neutral environments. Therefore, α-Cu-FeOOH material has great potential for practical application in textile wastewater treatment with an initial color of 185.6 mg/L and TOC concentration of 72.54 mg/L.

Oxidized pyrite as an efficient Fenton reagent to generate active species for the degradation of carbamazepine in a wide pH range

Few studies have reported the catalytic activity of oxidized pyrite. In the paper, oxidized pyrite was first explored as a Fenton reagent to generate active species to degrade carbamazepine (CBZ) in a wide pH range (3.0–11.0). The results showed that oxidized pyrite exhibited excellent catalytic performance on the activation of H2O2 to degrade CBZ with high stability. The influences of oxidized pyrite loading, H2O2 concentration, CBZ concentration, initial pH and co-existing ions on the degradation efficiency of CBZ were studied in detail. The main active species for the degradation of CBZ were HO, O2-, e- and 1O2, which were generated from the comprehensive effects of homogeneous Fenton, heterogeneous Fenton and photo-Fenton reaction. Furthermore, a possible pathway for CBZ degradation was proposed based on the intermediates detected from UPLC-MS/MS. Finally, the potential for practical utilization of oxidized pyrite was confirmed by degrading CBZ in tap water and secondary effluent water. The obtained results provide a new idea for the environment purification using natural pyrite.

Semi-pilot scale fluidized-bed reactor applied for the Azo dye removal from seawater by granular heterogeneous fenton catalysts

Not only is water an essential source for the existence of humans but also it is a necessity for creatures' life. Reutilizing wastewater is a salient way to conquer this rigor; many physical and chemical methods have been developed to treat wastewater, one of which is the advanced oxidation process (AOP). In this study, a heterogeneous Fenton reaction was employed to degrade a non-biodegradable organic contaminant (Direct Blue 71) from synthetic seawater. An unprecedented approach and a novel self-created autoclave were employed to synthesize granulated Fe3O4/Cellulose nanocomposites, which were applied in AOPs as catalysts. Characterization of prepared nanocomposites was investigated by various methods confirming that cellulose is uniformly covered by Fe3O4 nanoparticles. The AOP was carried out in two different kinds of batch and fluidized bed reactors. The impacts of three effectual parameters on the dye removal were weighed using response surface methodology (RSM). The obtained results for both systems demonstrated that exploiting 3.1 g/L catalysts besides the presence of 12.95 mM H2O2 could remove 33.12 mg/L dye entirely. In comparison to the batch reactor, only when the process was conducted in a fluidized bed reactor, did the elimination efficiency increase dramatically. Fluidization results indicated a significant enhancement in dye removal efficiency and a sensitive decrement in the degradation process time. The experimental results were in good agreement with the pseudo-first-order kinetic model and the fluidized bed reactor had a greater K value. The synthesized catalysts were biodegradable and they had an acceptable performance up to 6 cycles after each regeneration process.

Dynamic coordination of two-phase reactions in heterogeneous Fenton for selective removal of water pollutants

The •OH-mediated heterogeneous Fenton reaction has been widely applied despite the limitations of low pollutant selectivity and unclear oxidation mechanism. Here we reported an adsorption-assisted heterogeneous Fenton process for the selective degradation of pollutants and systematically illustrated its dynamic coordination in two phases. The results showed that the selective removal was improved by (i) surface enrichment of target pollutants via electrostatic interactions including real adsorption and adsorption-assisted degradation and (ii) inducing the diffusion of H2O2 and pollutants from the bulk solution to the catalyst surface to trigger the homogeneous and surface heterogeneous Fenton reactions. Furthermore, surface adsorption was confirmed as a crucial but not necessary step for degradation. Mechanism studies demonstrated that •O2– and Fe3+/Fe2+ cycle increased •OH generation, which remained active in two phases within ⁓244 nm. These findings are critical for understanding the removal behavior of complex targets and expanding heterogeneous Fenton applications.

Light-Driven Fuel Cell with a 2D/3D Hierarchical CuS@MnS Z-Scheme Catalyst for H2O2 Generation

A photoelectrocatalytic (PEC) oxygen reduction reaction (ORR) strategy with fuel-efficient and cost-effective catalysts for on-demand hydrogen peroxide (H2O2) production is booming as an attractive alternative to the conventional anthraquinone process. Herein, we constructed a novel two-dimensional (2D)/three-dimensional (3D) hierarchical CuS@MnS p-p Z-scheme catalyst with full spectrum absorption and strong coupling interface by regulating the crystal structure, morphology, and photocharge transfer mechanism, which was used as a photocathode for PEC synthesis of H2O2 with a yield of 1.65 mM within 180 min. Taking advantage of a coupling strategy with Sn3O4/Ni foam, the as-prepared two-compartment cell with water oxidation reaction and ORR exhibited boosted activity and stability for the dual production of H2O2. An energy-saving H2O2 generation system was also constructed with a direct hydrazine/O2 fuel cell, realizing the significant advantage in reducing electricity consumption during the H2O2 synthesis. Moreover, the onsite generation of H2O2 remarkably accelerated the degradation of pollutants via a cascade heterogeneous Fenton reaction with a Fe anode. This work provides a new strategy for designing a multifunctional PEC system for the production of high-value chemicals, energy recovery, and pollutant degradation.