Improving the Fenton catalytic performance of FeOCl using an electron mediator

Photocatalytic Synthesis of Ammonia from Hollow Coral-Like Graphitic Carbon Nitride/FeOCl Loaded with Fe-1T MoS2 Nanosheets as Cocatalysts

Photocatalytic ammonia synthesis (PAS) represents an emerging environmentally friendly approach to ammonia production. In this work, we employed Fe doping to modify the cocatalyst 1T MoS2, enhancing the active N2 sites on Fe-1T MoS2 by inducing defects on the surface of 1T MoS2. Afterward, Fe-1T MoS2 was loaded onto a hollow coral-like graphitic carbon nitride (CCN)/FeOCl composite. Under simulated sunlight, the efficiency of 5% Fe-1T MoS2@CCN/FeOCl (Fe-MCN/FeOCl) reached 367.62 μmol g-1 h-1, surpassing 1T MoS2@CCN(MCN) by 3.2 times, CCN by 16.9 times, and g-C3N4 by 32.5 times, where 5% means the doping amount of Fe in 1T MoS2. The good performance of Fe MCN/FeOCl should be attributed to the Fe doping in Fe-MCN/FeOCl which not only increases the separation efficiency of active sites and charge carriers, but also reduces the sample impedance significantly through the heterojunction formed between CCN and FeOCl. This work also presents a method for creating more efficient and stable photocatalysts for ammonia synthesis.

A two dimensional Co(OH)2 catalytic gravity-driven membrane for water purification: a green and facile fabrication strategy and excellent water decontamination performance

Cobalt-based materials are reported to be the most efficient catalysts in sulfate radical advanced oxidation processes (SR-AOPs). A green and facile method was developed in this work to prepare uniform Co(OH)2 hexagonal nanosheets, which was void of any organic solvents via mere ambient temperature stirring. The obtained nanosheets were assembled into a catalytic gravity-driven membrane, through which the removal efficiency of a typical pharmaceutical contaminant, ranitidine (RNTD), could reach ∼100% within 20 min. Meanwhile, the catalytic membrane also demonstrated effective removal performance towards various pollutants. In order to augment the long-term stability of catalytic membranes, Co(OH)2/rGO composites were fabricated using the same strategy, and a Co(OH)2/rGO catalytic membrane was prepared correspondingly. The Co(OH)2/rGO membrane could maintain a ∼100% removal of RNTD over a constant reaction period lasting for up to 165 hours, which was approximately 11 times that of the sole Co(OH)2 membrane (15 h). Analysis of element chemical states, metal ion concentration in filtrates, and quenching experiments suggested that the combination with rGO could promote the electron transfer to accelerate the Co(II) regeneration, restrain the cobalt dissolution to alleviate the active site loss, and contribute to the production of 1O2via synergistic effects of oxygen-containing groups in rGO. Toxicity assessment was performed on RNTD and its degradation intermediates to confirm the reduction in ecotoxicity of the treated feed. Overall, this work not only offered guidance for the application of nanosheets in AOP membranes, but also had implications for the environmentally-friendly preparation protocol to obtain functional metal hydroxides.

A sustainable solution for organic pollutant degradation: Novel polyethersulfone/carbon cloth/FeOCl composite membranes with electric field-assisted persulfate activation

Sulfate radical-based advanced oxidation processes (SR-AOP) and ultrafiltration (UF) membranes have demonstrated effectiveness in treating wastewater. This investigation illuminated a pioneering two-stage procedure for fabricating polyethersulfone/carbon cloth/FeOCl (PES/CC/FeOCl) composite catalytic membranes, exhibiting proficiency in persulfate activation. Evidenced by their distinctively high degradation rates and superior stability, these innovative composite membranes efficaciously obviate tetracycline (TC), showcasing a striking TC degradation rate, with an unparalleled removal ratio peaking at 93% under applied electrical fields. The process underlying persulfate activation and TC degradation was meticulously explored through electron paramagnetic resonance (EPR) and quenching trials. These evaluations unveil that hydroxyl radicals (•OH) and sulfate radicals (SO4•-) primarily drive the eradication of diminutive organic molecules. Subsequent studies emphasized the noteworthy rejection ratio of the PES/CC/FeOCl composite membranes (90%) for sodium alginate (SA), further revealing their exceptional on-line cleansing efficiency in an electrofiltration-associated in-situ oxidation system. In essence, this study proposed a novel approach for the synthesis of composite membranes adept at the catalytic degradation of organic pollutants. This paradigm-shifting research imparted a unique lens to perceive the integration of membrane separation technology, enriching the domain of advanced wastewater treatment strategies.

Promoted wet peroxide oxidation of chlorinated volatile organic compounds catalyzed by FeOCl supported on macro-microporous biomass-derived activated carbon

Chlorinated volatile organic compounds (CVOCs) are a recalcitrant class of air pollutants, and the strongly oxidizing reactive oxygen species (ROS) generated in advanced oxidation processes (AOPs) are promising to degrade them. In this study, a FeOCl-loaded biomass-derived activated carbon (BAC) has been used as an adsorbent for accumulating CVOCs and catalyst for activating H₂O₂ to construct a wet scrubber for the removal of airborne CVOCs. In addition to well-developed micropores, the BAC has macropores mimicking those of biostructures, which allows CVOCs to diffuse easily to its adsorption sites and catalytic sites. Probe experiments have revealed HO^• to be the dominant ROS in the FeOCl/BAC + H₂O₂ system. The wet scrubber performs well at pH 3 and H₂O₂ concentrations as low as a few mM. It is capable of removing over 90% of dichloroethane, trichloroethylene, dichloromethane and chlorobenzene from air. By applying pulsed dosing or continuous dosing to replenish H₂O₂ to maintain its appropriate concentration, the system achieves good long-term efficiency. A dichloroethane degradation pathway is proposed based on the analysis of intermediates. This work may provide inspiration for the design of catalyst exploiting the inherent structure of biomass for catalytic wet oxidation of CVOCs or other contaminants.

BiVO4 As a Sustainable and Emerging Photocatalyst: Synthesis Methodologies, Engineering Properties, and Its Volatile Organic Compounds Degradation Efficiency

Bismuth vanadate (BiVO₄) is one of the best bismuth-based semiconducting materials because of its narrow band gap energy, good visible light absorption, unique physical and chemical characteristics, and non-toxic nature. In addition, BiVO₄ with different morphologies has been synthesized and exhibited excellent visible light photocatalytic efficiency in the degradation of various organic pollutants, including volatile organic compounds (VOCs). Nevertheless, the commercial scale utilization of BiVO₄ is significantly limited because of the poor separation (faster recombination rate) and transport ability of photogenerated electron-hole pairs. So, engineering/modifications of BiVO₄ materials are performed to enhance their structural, electronic, and morphological properties. Thus, this review article aims to provide a critical overview of advanced oxidation processes (AOPs), various semiconducting nanomaterials, BiVO₄ synthesis methodologies, engineering of BiVO₄ properties through making binary and ternary nanocomposites, and coupling with metals/non-metals and metal nanoparticles and the development of Z-scheme type nanocomposites, etc., and their visible light photocatalytic efficiency in VOCs degradation. In addition, future challenges and the way forward for improving the commercial-scale application of BiVO₄-based semiconducting nanomaterials are also discussed. Thus, we hope that this review is a valuable resource for designing BiVO₄-based nanocomposites with superior visible-light-driven photocatalytic efficiency in VOCs degradation.

A novel scheme to improve the photo-Fenton performance of iron oxychloride by carbon: Three existent states and roles of carbon in the degradation of tetracycline in water

The photo-Fenton process is promising for sincerely treating contaminated water. In this work, carbon-decorated iron oxychloride (C-FeOCl) is synthesized as a photo-Fenton catalyst for removing tetracycline (TC) from water. Three actual states of carbon are identified and their different roles in enhancing photo-Fenton performance are revealed. All carbon on/in FeOCl, including graphite carbon, carbon dots and lattice carbon, enhance visible light adsorption. More importantly, a homogeneous graphite carbon on the outer surface of FeOCl accelerates the transportation-separation of photo-excited electrons along the horizontal direction of FeOCl. Meanwhile, the interlayered carbon dots offer a FeOC bridge in helping the transportation-separation of photo-excited electrons along the vertical direction of FeOCl. In this way, C-FeOCl acquires isotropy in conduction electrons to ensure an efficient Fe(II)/Fe(III) cycle. These interlayered carbon dots extend the layer spacing (d) of FeOCl to about 1.10 nm, exposing the internal iron centers. The lattice carbon significantly increases the amounts of coordinatively unsaturated iron sites (CUISs) in activating hydrogen peroxide (H₂O₂) to hydroxyl radical (OH). Density functional theory (DFT) calculations confirm this activation on inner and external CUISs with a significantly low activation energy of about 0.33 eV.

Regulating Interlayer Confinement FeOCl for Accelerating Polymerization of Pollutants to Reduce Carbon Emission in Water Purification

The spatial structure regulation of catalysts could optimize the reaction pathway and enhance the mass transfer kinetics, which might realize the efficient and low-consumption removal of pollutants in Fenton-like technology. In this study, N,N-dimethylformamide (DMF) intercalation was used to adjust the interlayer spacing of FeOCl from 7.90 to 11.84 Å by a simple and rapid intercalation method, thereby enhancing the mass transfer kinetics and altering the catalytic pathway. The removal rate of BPA in the DMF-FeOCl/PS system increased by 8.78 times, showing good resistance to complex water environments (such as pH, humic acid, and anions), especially in 5 g/L high-salt wastewater. The direct electron transfer processes between Fe(IV) and pollutants mediated by interlayer Fe sites generate phenoxy radicals, and the polymerization processes occur, achieving efficient removal of pollutants and low CO₂ emissions. This study provides new insight into the efficient and low-carbon treatment of high-salt wastewater.

Oxoiron(IV)-dominated Heterogeneous Fenton-like Mechanism of Fe-Doped MoS2

Oxoiron(IV) species are a critical intermediate in the Fe-based Fenton-like process at circumneutral pH, and its oxidative reactivity is closely related to the ligands. An optional inorganic host material, MoS₂ , is selected to construct a highly reactive sulfur ligand coordinated Fe species in this work. The Fe species doped in MoS₂ is presented as the Fe^II centre and triggers the transformation of the 2H phase to the octahedral 1T phase MoS₂ . The role of the interaction between doped Fe and the MoS₂ host lattice on the formation of oxoiron(IV) is studied. A significant Fenton-like reactivity and a remarkable accumulation of oxoiron(IV) species were observed for Fe-MoS₂ . The quenching experiment was implemented to disclose the predominant role of oxoiron(IV) species in the Fe-MoS₂ /H₂ O₂ Fenton-like system. Furthermore, oxoiron(IV) species could transform into the ⋅O₂ ^- and ¹ O₂ , which further expedites the Fenton-like reaction.

Degradation of methylene blue by an E-Fenton process coupled with peroxymonosulfate via free radical and non-radical oxidation pathways

This paper reports a combined advanced oxidation process to degrade methylene blue and investigates its oxidation mechanism and degradation pathway.

Enhanced Heterogeneous Fenton-like Process for Sulfamethazine Removal via Dual-Reaction-Center Fe-Mo/rGO Catalyst

A heterogeneous Fenton-like catalyst with single redox site has a rate-limiting step in oxidant activation, which limited its application in wastewater purification. To overcome this, a bimetallic doping strategy was designed to prepare a heterogeneous Fenton-like catalyst (Fe-Mo/rGO) with a double-reaction center. Combined with electrochemical impedance spectroscopy and density functional theory calculation, it was confirmed that the formation of an electron-rich Mo center and an electron-deficient Fe center through the constructed Fe-O-Mo and Mo-S-C bonding bridges induced a higher electron transfer capability in the Fe-Mo/rGO catalyst. The designed Fe-Mo/rGO catalyst exhibited excellent sulfamethazine (SMT) degradation efficiency in a broad pH range (4.8-8.4). The catalytic performance was hardly affected by inorganic anions (Cl^-, SO₄^2- and HCO₃^-) in the complicated and variable water environment. Compared to Fe/rGO and Mo/rGO catalysts, the SMT degradation efficiency increased by about 14.6 and 1.6 times in heterogeneous Fenton-like reaction over Fe-Mo/rGO catalyst. The electron spin resonance and radical scavenger experiments proved that ·O₂^-/HO₂· and ¹O₂ dominate the SMT removal in the Fe-Mo/rGO/H₂O₂ system. Fe and Mo, as active centers co-supported on rGO, significantly enhanced the electron transfer between catalyst, oxidant, and pollutants, which accelerated the reactive oxygen species generation and effectively improved the SMT degradation. Our findings offer a novel perspective to enhance the performance of heterogeneous Fenton-like catalysts by accelerating the electron transfer rate in the degradation of organic pollutants.

Adsorption-enforced Fenton-like process using activated carbon-supported iron oxychloride catalyst for wet scrubbing of airborne dichloroethane

Wet scrubbing is a low-cost process for disposing of air pollutants. Nevertheless, this method is rarely used for the treatment of volatile organic compounds (VOCs) because of their poor water solubility. In this study, we used a unique wet scrubbing system containing H₂O₂ and activated carbon (AC)-supported iron oxychloride (FeOCl) nanoparticles to remove airborne dichloroethane (DCE). The operating conditions of the wet scrubber were optimized, and the mechanism was explored. The results showed that the adsorption of dissolved DCE onto AC promoted its transfer from air to water, while the accumulation of DCE on AC facilitated its oxidation by •OH generated on FeOCl catalyst. The wet scrubber performed well at pH 3 and low H₂O₂ concentrations. By pulsed or continuous dosing H₂O₂, the cooperative adsorption-catalytic oxidation allowed long-term DCE removal from air. Benefiting from satisfactory cost-effectiveness, avoidance of toxic byproduct formation, and less corrosion and catalyst poisoning, wet scrubbers coupled with cooperative adsorption and heterogeneous advanced oxidation processes could have broad application potentials in VOC control.

Visible-light photoelectrocatalysis/H2O2 synergistic degradation of organic pollutants by a magnetic Fe3O4@SiO2@mesoporous TiO2 catalyst-loaded photoelectrode

In this paper, we describe a method for photoelectrocatalysis (PEC)/H₂O₂ synergistic degradation of organic pollutants with a magnetic Fe₃O₄@SiO₂@mesoporous TiO₂ (FST) photocatalyst-loaded electrode. At optimal conditions of pH 3.0, 2.25% H₂O₂, working electrode (fixed FST 30 mg) potential +0.6 V (vs. SCE), and 10 mg L^-1 of all experimental pollutants, the FST PEC/H₂O₂ synergistic system exhibited high activity and stability for the removal of various organic pollutants under visible light with comparable degradation efficiencies, including MB (98.8%), rhodamine B (Rh B, 96.7%), methyl orange (MO, 97.7%), amoxicillin (AMX, 83.9%). Moreover, this system obtained TOC removal ratios of 83.5% (MB), 77.9% (Rh B), 80.2% (MO), 65.5% (AMX) within 8 min. The kinetic rate constants of the PEC/H₂O₂ synergistic system were nearly 53 and 1436 times higher than that of the PEC process and H₂O₂ photolysis under visible light, respectively. Furthermore, the main reactive oxidant species (˙OH, ˙O₂ ^-) were studied and enhanced mechanisms of the photocatalytic-electro-H₂O₂ coupling system were proposed. This work brings new insights to efficiently purify organic pollutants by PEC coupled with peroxide under solar light illumination.

Efficient removal of neonicotinoid by singlet oxygen dominated MoSx/ceramic membrane-integrated Fenton-like process

Removal of neonicotinoids (NEOs) from contaminated water is of great importance for both ecological environment and human health. However, conventional Fenton process might be insufficient for NEOs removal due to short lifetime for generated HO^• and limited Fe³⁺/Fe²⁺ redox cycle. Advancing Fenton process to produce singlet oxygen can be an effective route to improve its efficacy for NEOs removal. Herein, we developed a molybdenum sulfide modified ceramic membrane-integrated Fenton-like system to achieve efficient catalytic removal of NEOs. The reduced Mo⁰ and Mo⁴⁺ could promote the reduction process of Fe³⁺ to Fe²⁺, improving the activation efficiency of hydrogen peroxide (H₂O₂) and the generation of superoxide radical (O₂^•-). Consequently, the coexisting Mo⁶⁺ reacted with O₂^•- to generate ¹O₂. The membrane enabled the pollutants to adequately contact oxidants due to the enhanced convective mass transfer. The functionalized membrane exhibited stable catalytic performance for clothianidin (CLO, a kind of NEOs, 10 mg/L) removal (degradation efficiency > 85%). The presence of ¹O₂ enabled the dechlorination and hydroxylation of CLO and thus reduced the toxicity of wastewater. Our work sheds light on the use of functionalized ceramic membrane integrated catalytic Fenton system for effective environmental remediation.

Disinfection through Advance Oxidation Processes: Optimization and Application on Real Wastewater Matrices

Disinfection is an essential and significant process for water treatment to protect the environment and human beings from pathogenic infections. In this study, disinfection through the generation of hydroxyl (Fenton process (FP)) and sulfate (Fenton-like process (FLP)) radicals was validated and optimized. The optimization was carried out in synthetic water through an experimental design methodology using the bacteria Escherichia coli as a model microorganism. Different variables were evaluated in both processes: precursor concentration (peroxymonosulfate (PMS) and H₂O₂), catalyst concentration (Fe⁺²), and pH in the Fenton process. After that, the optimized conditions (FP: 132.36 mM H₂O₂, 0.56 mM Fe⁺² and 3.26 pH; FLP: 3.82 mM PMS and 0.40 mM Fe⁺²) were applied to real matrices from wastewater treatment plants. The obtained results suggest that both processes are promising for disinfection due to the high oxidant power of hydroxyl and sulfate radicals.

A review on the degradation of acetaminophen by advanced oxidation process: pathway, by-products, biotoxicity, and density functional theory calculation

Water scarcity and the accumulation of recalcitrance compounds into the environment are the main reasons behind the attraction of researchers to use advanced oxidation processes (AOPs). Many AOP systems have been used to treat acetaminophen (ACT) from an aqueous medium, which leads to generating different kinetics, mechanisms, and by-products. In this work, state-of-the-art studies on ACT by-products and their biotoxicity, as well as proposed degradation pathways, have been collected, organized, and summarized. In addition, the Fukui function was used for predicting the most reactive sites in the ACT molecule. The most frequently detected by-products in this review were hydroquinone, 1,4-benzoquinone, 4-aminophenol, acetamide, oxalic acid, formic acid, acetic acid, 1,2,4-trihydroxy benzene, and maleic acid. Both the experimental and prediction tests revealed that N-(3,4-dihydroxy phenyl) acetamide was mutagenic. Meanwhile, N-(2,4-dihydroxy phenyl) acetamide and malonic acid were only found to be mutagenic in the prediction test. The findings of the LC50 (96 h) test revealed that benzaldehyde is the most toxic ACT by-products and hydroquinone, N-(3,4-dihydroxyphenyl)formamide, 4-methylbenzene-1,2-diol, benzoquinone, 4-aminophenol, benzoic acid, 1,2,4-trihydroxybenzene, 4-nitrophenol, and 4-aminobenzene-1,2-diol considered harmful. The release of them into the environment without treatment may threaten the ecosystem. The degradation pathway based on the computational method was matched with the majority of ACT proposed pathways and with the most frequent ACT by-products. This study may contribute to enhance the degradation of ACT by AOP systems.

Unraveling timescale-dependent Fe-MOFs crystal evolution for catalytic ozonation reactivity modulation

Iron-based metal-organic frameworks (Fe-MOFs) have been considered competitive catalyst candidates for the effective degradation of organic pollutants via advanced oxidation processes (AOPs) due to their unique porous architecture and tunable active site structure. However, little is known about the role of synergetic relationship between porous architecture and active site exposure of Fe-MOFs on catalysis for AOPs yet. Here, we demonstrated an overlooked compromise over these two features on modulating the catalytic ozonation reactivity of MIL-53(Fe) through a timescale-dependent crystal evolution. Enabled by intramolecular hydrogen bonds, the MIL-53(Fe) was subjected to six evolution steps in terms of crystal morphology, leading to a volcano plot of catalytic ozonation reactivity for Rhodamine B (RhB) degradation versus the crystallization time. Evidence suggested that the surface area of MIL-53(Fe) decreased dramatically, while the density of accessible active site increased when prolonging crystallization time, allowing for the facile modulation of catalytic ozonation reactivity of MIL-53(Fe). Electron paramagnetic resonance and fluorescence quantification tests verified that the screened MIL-53(Fe)s had a much better capacity for ∙OH generation than benchmark ozonation catalyst α-MnO₂ and α-FeOOH. Moreover, the MIL-53(Fe) with the highest reactivity (i.e., MIL-53(Fe)-18H) could effectively destruct a broad spectrum of emerging and refractory organic pollutants and allow the thorough purification of secondary effluents discharged from textile dyeing & finishing industry for in situ reuse. Therefore, our study advances the understanding of the compromise effect between porous architecture and active site on catalysis reactivity of Fe-MOFs and promotes the rational design of more effective Fe-MOFs as well as their derivatives for environmental applications.

Highly dispersed of Ag/AgCl nanoparticles on exfoliated FeOCl nanosheets as photo-Fenton catalysts for pollutants degradation via accelerating Fe(II)/Fe(III) cycle

In this work, Ag/AgCl/FeOCl (Ag-Fe) catalysts were successfully prepared via multistep routes in which Ag was uniformly anchored to the enriched Cl sites provided by exfoliated FeOCl nanosheets. Among these Ag-Fe catalysts, 5% Ag-Fe exhibited the highest pseudo first-order kinetic constant 0.1056 min^-1 for photo-Fenton degradation of Rhodamine B (RhB), which was 11 times higher than that of FeOCl (0.0096 min^-1). Ag-Fe catalysts exposed more coordinatively unsaturated Fe active sites to coordinate with H₂O₂ due to the cleavage of Fe-Cl bond. The exposed coordinatively unsaturated Fe(III) active sites could capture the photoinduced electrons and reduce them to Fe(II), which boosted the separation efficiency of photogenerated charge carriers. Meanwhile, the photogenerated electrons of Ag⁰ transferred to the FeOCl, promoting the reduction of Fe(III) to Fe(II). In addition, the intensified visible light adsorption (SPR effect) was achieved after introducing Ag/AgCl nanoparticles on exfoliated FeOCl. Hydroxyl radicals (·OH) and holes (h⁺) were determined as the main reactive oxidative species (ROS) in the photo-Fenton degradation process.

Removal of Gaseous Hydrogen Sulfide by a FeOCl/H2O2 Wet Oxidation System

The removal of gaseous hydrogen sulfide using FeOCl/H₂O₂ was studied. The effects of the FeOCl dosage, the H₂O₂ concentration, the reaction temperature, and the gas flow rate on the removal of H₂S were investigated. The reaction products were analyzed, and the characterization of FeOCl was carried out by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and electron paramagnetic resonance spectroscopy. Furthermore, radical quenching experiments were carried out using butylated hydroxytoluene, isopropanol, and benzoquinone. It was found that the H₂S removal rate for a H₂S gas concentration of 160 ppm reached 85.6% when bubbling through 100 mL of an aqueous solution containing FeOCl (1 g/L) and H₂O₂ (0.33 mol/L) at 293 K with a flow rate of 135 mL/min. Although the dissolution of chlorine in FeOCl was found to result in reduced catalytic performance, the activity was restored after soaking the catalyst in concentrated hydrochloric acid (37%) and subsequent calcination. The mechanism of H₂S removal was also discussed, and it was found that this process was controlled by H₂S diffusion. FeOCl was found to activate H₂O₂ and produce radicals, such as ^•OH and ^•O₂ ^-, resulting in the formation of a water film rich in radicals on the FeOCl surface. Following the diffusion of H₂S into the water film, it underwent oxidation by radicals to produce SO₄ ^2-. Overall, the catalyst and the product can be effectively separated.

New and highly efficient Ultra-thin g-C3N4/FeOCl nanocomposites as photo-Fenton catalysts for pollutants degradation and antibacterial effect under visible light

The photo-Fenton reaction was widely used in the removal of pollutants in waste water, which makes it exhibit great potential in the field of environmental remediation. Hence, it is crucial to explore a new efficient and stable photo-Fenton catalyst driven by visible light. In this work, a simple two-step calcination method was used to synthesize sheet-like stacked Ultra-thin g-C₃N₄/FeOCl (CNF) materials. The morphology, composition, photo-Fenton performance, and antibacterial properties were systematically analyzed. Research results exhibited that the synthesized CNF catalysts showed enhanced visible light absorption capacity and excellent photo-Fenton performance. Compared with FeOCl alone, CNF displayed stronger degradation ability for rhodamine B (RhB) and could achieve 97% degradation within 9 min, which was about 10 times that of pure FeOCl. At the same time, the composite catalysts exhibited excellent antibacterial effects under photo-Fenton conditions. The antibacterial rate of CNF composite catalyst under photo-Fenton conditions can reach almost 99%, which was 3 times that of photocatalysis alone and 2 times that of Fenton alone. The heterojunction formed between Ultra-thin g-C₃N₄ and FeOCl promoted the separation of e^- and h⁺. Simultaneously, the presence of e^- promoted the cycle of Fe³⁺ and Fe²⁺ in FeOCl, thereby promoting the generation of hydroxyl radicals (OH) from H₂O₂ and improving the photo-Fenton activity to achieve the effect of degrading pollutants and antibacterial. The photo-Fenton catalysis and degradation mechanism were analyzed in detail. This work provided a theoretical basis for the application of CNF material in the removal of wastewater.

Self-assembly of MoS2 nanosheet adhered on Fe-MOF heterocrystals for peroxymonosulfate activation via interfacial interaction

A novel heterogeneous catalyst PB@MoS₂ was successfully synthesized via facile hydrothermal processes and identified as a superior peroxymonosulfate (PMS) activator for organic pollutants degradation under visible light irradiation. The MoS₂ nanosheet is uniformly adhered to the surface of iron-based metal-organic framework Prussian blue (PB) cube, exhibiting a tightly hydrangeas-like structure. Benefiting from strongly interfacial interaction (FeMo-sulfide) between PB and MoS₂, as confirmed by ⁵⁷Fe M̈össbauer spectra and electrochemical measurement, the PB@MoS₂ catalyst significantly accelerate the charge carrier transfer via interfacial FeMo-sulfide and thereby improve PMS activation ability to generate abundant reactive radicals. Moreover, the crucial iron active site was steadily validated by introduction of sodium oxalate trapping agent and visible light. In summary, the visible light induced Fenton-like reaction over PB@MoS₂ catalyst promoted the Fe^II/Fe^III cycling and electron transport and further triggered the reactive species (SO₄^-, OH, O₂^- and h⁺) productivity, realizing an extraordinarily high degradation and mineralization efficiency for various refractory organic pollutants. This work would provide a deep insight into develop heterogeneous Fe-based metal organic framework/MoS₂ catalyst for environmental restoration and remediation by photo-Fenton reaction.

Preparation and performance of Novel Ni-doped Iron oxychloride with High singlet oxygen generation

Singlet oxygen with lower oxide electrode potential but higher selective oxidation ability towards specific organic contaminants had been paid great attention. An efficient system with high singlet oxygen generation (over...

The mineralization ability of a chloride-resistant γ-Cu2(OH)3Cl Fenton catalyst: effects of the cation type, salt concentration and organic pollutants

A chloride-resistant heterogeneous Fenton catalyst γ-Cu2(OH)3Cl is used to mineralize aromatic organics (phenol, bisphenol A, salicylic acid and aniline) in saline solutions with different salts (MgCl2, CaCl2, NaCl and KCl) and concentrations.

Enhancing iron redox cycling for promoting heterogeneous Fenton performance: A review

Conventional water treatment methods are difficult to remove stubborn pollutants emerging from surface water. Advanced oxidation processes (AOPs) can achieve a higher level of mineralization of stubborn pollutants. In recent years, the Fenton process for the degradation of pollutants as one of the most efficient ways has received more and more attention. While homogeneous catalysis is easy to produce sludge and the catalyst cannot be cycled. In contrast, heterogeneous Fenton-like reaction can get over these drawbacks and be used in a wider range. However, the reduction of Fe (III) to Fe(II) by hydrogen peroxide (H₂O₂) is still the speed limit step when generating reactive oxygen species (ROS) in heterogeneous Fenton system, which restricts the efficiency of the catalyst to degrade pollutants. Based on previous research, this article reviews the strategies to improve the iron redox cycle in heterogeneous Fenton system catalyzed by iron materials. Including introducing semiconductor, the modification with other elements, the application of carbon materials as carriers, the introduction of metal sulfides as co-catalysts, and the direct reduction with reducing substances. In addition, we also pay special attention to the influence of the inherent properties of iron materials on accelerating the iron redox cycle. We look forward that the strategy outlined in this article can provide readers with inspiration for constructing an efficient heterogeneous Fenton system.

In situ synthesis of FeOCl@MoS2 on graphite felt as novel electro-Fenton cathode for efficient degradation of antibiotic ciprofloxacin at mild pH

The traditional Electro-Fenton (EF) is an efficient technology for wastewater treatment but suffers from the acidic condition requirement and external catalyst addition. To overcome these challenges, a GF@MoS₂@FeOCl cathode was fabricated using a facile method. The as-prepared GF@MoS₂@FeOCl cathode showed excellent performance for ciprofloxacin (CIP) degradation in EF process with RuO₂/Ti electrode as the anode. H₂O₂ was electro-generated and activated on-site at the cathode at mild pH without adding Fe²⁺. CIP was 100% removed with 74.4% of mineralization in 90 min at pH 6. The GF@MoS₂@FeOCl cathode exhibited good reusability after consecutive runs of degradation. The degradation intermediates were investigated, and the possible mechanism was proposed. This work demonstrated that the prepared GF@MoS₂@FeOCl cathode is a promising candidate for contaminants treatment in an EF system.

Constructing MoS2/Lignin-derived carbon nanocomposites for highly efficient removal of Cr(VI) from aqueous environment

Effective removal of Cr(VI) pollution from aquatic environment is in pressing need because of the detrimental effect of Cr(VI) to human health. Herein, we report a facile two-step approach to synthesis MoS₂/Lignin-derived Carbon (MoS₂@LDC) nanocomposites for highly efficient elimination of Cr(VI) from aqueous solutions. The MoS₂@LDC exhibited outstanding removal efficient for Cr(VI) (198.70 mg/g at pH = 2.0, T = 298.15 K and C_Initial = 20.0 mg/L). 99.35% of Cr(VI) can be removed by the composites in 30 min. Thermodynamic and kinetic studies suggest the removal of Cr(VI) is through both adsorption and reduction. The performance of MoS₂@LDC can be further enhanced by hydrogen plasma treatments, which was attributed to the sulfur vacancies induced improvement in the reduction activity of MoS₂ layer. The results of this work can guide the rational design of high-performance nanocomposite for efficient remediation of heavy metals in aquatic environment.

BiOBr/MoS2 catalyst as heterogenous peroxymonosulfate activator toward organic pollutant removal: Energy band alignment and mechanism insight

Utilization of heterogenous catalysts to trigger peroxymonosulfate (PMS) activation is considered an efficient strategy for environmental decontamination. Herein, a tightly bonded flake-like 2D/2D BiOBr/MoS₂ heterojunction was successfully designed through co-precipitation process. By virtue of matched energy levels and intimate interfacial coupling, the Type-II BiOBr/MoS₂ heterojunction significantly expedited charge carrier transfer and thereby promoted the catalytic performance for organic dye oxidation and Cr(VI) reduction. The specially designed BiOBr/MoS₂ heterojunction is also conducive to split PMS and continuously generated highly active species (SO₄^-, OH and O₂^-) in a photo-Fenton system, achieving extraordinary catalytic capacity for various emerging organic pollutants (including phenol, bisphenol A and carbamazepine). The photoexcited electron with prolonged lifetime and exposed Mo sites with multivalence and multiphase nature can effectively activate PMS, which further promotes the oxidation efficiency of holes, as confirmed by scavenging experiments. The excellent stability and oxidative properties could justify scale up using BiOBr/MoS₂ to a small pilot test, implementing the potential value in practical applications. This study would provide novel insight and cognition of PMS activation via a superior heterojunction for complex polluted wastewater treatment.

MoS2-assisted Fe2+/peroxymonosulfate oxidation for the abatement of phenacetin: efficiency, mechanisms and toxicity evaluation

In this study, molybdenum disulfide (MoS₂) was chosen as a co-catalyst to enhance the removal efficiency of phenacetin (PNT) in water by a ferrous ion-activated peroxymonosulfate (Fe²⁺/PMS) process. Operating parameters, such as the initial solution pH and chemical dose on PNT degradation efficiency were investigated and optimized. Under an initial pH of 3, an Fe²⁺ dose of 25 μM, a PMS dose of 125 μM and a MoS₂ dose of 0.1 g L⁻¹, the degradation efficiency of PNT reached 94.3%, within 15 min. The presence of common water constituents including Cl⁻, HCO₃⁻, SO₄²⁻ and natural organic matter (NOM) will inhibit degradation of PNT in the MoS₂/Fe²⁺/PMS system. Radical quenching tests combined with electron paramagnetic resonance (EPR) results indicated that in addition to free radical species (˙OH, SO₄˙⁻ and O₂˙⁻), nonradical reactive species (¹O₂) were also crucial for PNT degradation. The variations in the composition and crystalline structure of the MoS₂ before and after the reaction were characterized by XPS and XRD. Further, the degradation pathways of PNT were proposed according to the combined results of LC/TOF/MS and DFT calculations, and primarily included hydroxylation of the aromatic ring, cleavage of the C–N bond of the acetyl-amino group, and cleavage of the C–O bond of the ethoxy group. Finally, toxicity assessment of PNT and its products was predicted using the ECOSAR program.

Performance, mechanisms and toxicity evaluation of PNT degradation by the MoS₂/Fe²⁺/PMS system were investigated.

In situ preparation of g-C3N4 nanosheet/FeOCl: Achievement and promoted photocatalytic nitrogen fixation activity

Climate change, global warming, and population growth have led researchers to use eco-sociable procedures for the N₂ reduction reaction. It has discovered that N₂ molecule can be transformed into NH₃ in ambient circumstances with nanocomposites upon visible irradiation. In this research paper, a new visible-light-driven photocatalyst was constructed, with various weight percents of FeOCl particles (10, 20, 30, and 40%) that have adhered on NS-CN. Subsequently, multiple features of the nanocomposites were assayed in detail. The results illustrated that the NS-CN/FeOCl (20%) system has remarkable photoactivity in the NH₄⁺ production reaction in comparison with the NS-CN and CN, which showed 2.5 and 8.6 higher activity, respectively. The durability of NS-CN/FeOCl (20%) system, as a substantial factor, was assayed for 5 recycles. Moreover, the effect of electron quenchers, pH of media, and solvent was studied. At last, a feasible Z-scheme mechanism for the remarkable improvement of N₂ fixation efficiency was offered.

A facile one-step synthesis of super-hydrophilic (NH4)0.33WO3/WS2 composites: a highly efficient adsorbent for methylene blue

Super-hydrophilic ATBDs-3 composites synthesized using a hydrothermal method only needed less than 2 min to attain more than 80% of the MAC (80.45 mg g⁻¹).