Heterogeneous Fenton-like System Research Articles

Efficient degradation of methylene blue at near neutral pH based on heterogeneous Fenton-like system catalyzed by Fe2O3/MnO2

The contamination of aquatic environments by organic dye contaminants in industrial wastewater has attracted widespread global attention. The heterogeneous Fenton-like process presents an attractive method for degrading dye pollutants, especially when such reactions are conducted under neutral pH. In this study, Fe2O3/MnO2 composite was employed as a novel heterogeneous catalyst for activating hydrogen peroxide (H2O2) to oxidize and subsequently degrade methylene blue (MB) under neutral pH. Multiple characterization results have confirmed the presence of MnO2 and Fe2O3 as the primary phases of the synthesized compound catalyst. Degradation experiments have demonstrated that the degradation efficiency of MB approaches 100% under the conditions of H2O2 concentration of 0.30% and Fe2O3/MnO2 amount of 0.888 g/L. Furthermore, the Fe2O3/MnO2 catalyst exhibits consistent and outstanding catalytic activity within a broad pH range from 5 to 9 benefiting from the strong interface interaction in Fe2O3/MnO2. The investigation into the kinetics of the Fenton-like reaction indicates that the catalytic degradation of MB by Fe2O3/MnO2 in conjunction with H2O2 follows pseudo-first-order kinetics. Moreover, supplementary scavenging experiments have demonstrated the crucial role played by hydroxyl radicals (·OH) in the catalytic oxidation mechanism of MB. This study offers a promising catalyst for the treatment of dye-containing wastewater under neutral pH condition.

Preparation of magnetic biochar used bioleached sludge to enhance tetracycline removal in a heterogeneous Fenton-like system

The environmental application of iron (Fe)-rich acidic sludge generated after bioleaching is still a challenge. Pyrolysis offers a promising avenue for converting this sludge into biochar. In this study, magnetic biochar (BLS-BC7) was prepared from acidic Fe-rich sludge and employed as a catalyst for tetracycline (TC) degradation by hydrogen peroxide (H2O2). Furthermore, compared with the original sludge-based biochar, BLS-BC exhibited a 2.3 times higher specific surface area, providing more active sites for the catalytic reactions. The scanning electron microscopy and Raman results indicated that BLS-BC7 was coated with a large number of particles on its surface, presenting a rough appearance with a high degree of defects, thereby providing more active sites for biochar. Characterization via photoelectron spectroscopy, elemental analysis, and Fourier transform infrared spectroscopy results indicated that BLS-BC contained a higher amount of oxygen functional groups, along with an increased content of CO and the formation of Fe–O, facilitating H2O2 activation to generate reactive oxygen species (ROS). Additionally, quenching experiments and electron paramagnetic resonance spectroscopy demonstrated the generation of multiple ROS such as 1O2, ·OH, and O2−·, in the BLS-BC7/H2O2 system. This resulted in a TC removal rate of 100 % within 120 min, with a mineralization rate of 53.4 %. The biochar exhibited easy recoverability and strong reusability, maintaining a TC removal rate of 91.3 % after five cycles of experiments. The X-ray diffraction patterns before and after the reaction showed that BLS-BC7 exhibited strong stability, with no apparent change in peak positions before and after use.

Boosting the Ni(II)-EDTA decomplexation and Ni(II) immobilization in a heterogeneous Fenton-like system with L-cysteine functionalized zero-valent iron

The remarkable stability and detrimental environmental impacts of nickel(II)-ethylenediaminetetraacetic acid (Ni(II)-EDTA) complexes originated from electroplating effluents have sparked a growing curiosity about their efficient remediation. In this study, L-cysteine functionalized zero-valent iron (C-ZVIbm) was synthesized via a ball-milling method and employed as a heterogeneous Fenton-like catalyst to decomplex Ni(II)-EDTA and immobilize Ni(II) from wastewater. The results demonstrated that the pseudo-second-order kinetic rate constant (2.096 L·mol−1·min−1) for EDTA degradation in the C-ZVIbm/H2O2 system was 123.3 times that in the ZVIbm/H2O2 system (0.017 L·mol−1·min−1). The incorporation of L-cysteine onto the surface of ZVI significantly enhanced the H2O2 activation, reactive oxygen species (OH, O2−, and 1O2) generation, and the sequential Ni(II)-EDTA decomplexation and EDTA degradation. The results of capture experiments revealed that 1O2 played a crucial role in the degradation of EDTA in the C-ZVIbm/H2O2 system. The optimization of the experimental variables indicated that the degradation of EDTA and the reduction/adsorption of Ni(II) were antagonistic in the C-ZVIbm/H2O2 system, resulting in an efficient reduction/immobilization of Ni(II) and an inhibition of EDTA degradation at a higher dosage of C-ZVIbm. Our findings provide new insights into the promising heterogeneous Fenton-like process that enables the decomplexation of Ni(II)-EDTA, the degradation of EDTA, and the synchronous immobilization of Ni(II).

Decolorization of C.I. Reactive Blue 78 dyeing wastewater in the chitosan-gelatin composite copper polymer/sodium persulfate system

Chitosan-gelatin composite copper polymer (CG for short) was prepared as an adsorption catalyst. The CG was combined with sodium persulfate to construct a heterogeneous Fenton-like system, which was applied to the decolorization of C.I. Reactive Blue 78 dyeing wastewater. The effects of sodium persulfate, CG, temperature, initial dyeing wastewater pH value and additives (sodium chloride, sodium carbonate) on the decolorization were investigated. The results show that the decolorization percentage of 0.1 g/L C.I. Reactive Blue 78 dyeing wastewater can reach 93.84 % under the conditions of sodium persulfate dosage of 0.3 g/L, CG dosage of 0.8 g/L, decolorization at 40 °C for 30 min. At the same time, the catalytic system has the characteristic of good decolorization effect on C.I. Reactive Blue 78 dyeing wastewater within a wide pH values range of 3–9. Even for dyeing wastewater containing 0.4 g/L high concentration C.I. Reactive Blue 78, the decolorization percentage can reach over 90 % after decolorization at 40 °C for 2 h. Moreover, CG can be reused. After repeated use of CG four times, the decolorization percentage of C.I. Reactive Blue 78 dyeing waste remains above 90 %. In addition, the weight loss rate of CG after each decolorization is less than 12 %. However, the presence of sodium chloride and sodium carbonate in the dyeing wastewater is not conducive to the decolorization of C.I. Reactive Blue 78 by the system.

Highly fast and efficient coupled Fe/Sn galvanic nanocatalyst with H2O2 Fenton-like process for synergistic reduction–oxidation of nitroaromatic compound

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

Exothermic Reaction in the Cleaning of Wastewater by a Fe2O3/Coconut Shell Activated Carbon/H2O2 Heterogeneous Fenton-like System

Energy utilization in wastewater degradation has important implications for sustainability; however, efficient multiphase Fenton-like catalysts are still needed. In this study, a heterogeneous Fe2O3/coconut shell activated carbon (CSAC) Fenton-like catalyst was prepared and evaluated with respect to degradation performance and exothermic reaction for the treatment of organic wastewater. Fe2O3@CSAC retained the porous morphology of CSAS, and Fe2O3 was uniformly loaded on the surface of CSAS. In the reaction system, the degradation rate of wastewater was higher and a large amount of heat was released; therefore, it could be applied to the energy recovery from wastewater source heat pump technology. The degradation rate of 300 mL of o-phenylenediamine solution with a concentration of 0.04 mol·L−1 was 89.0% under 0.25 mol·L−1 H2O2, 532 g·L−1 Fe2O3@CSAC, pH 7.1, and an initial reaction temperature of 30 °C, elevated to 7.9 °C. These findings clearly demonstrate the degradation performance and exothermic laws of the Fe2O3@CSAC/H2O2 multiphase Fenton-like system.

Coupled homogeneous/heterogeneous Fenton-like system to enhance the synchronized decontamination of aqueous tetracycline and Salmonella typhi

Aqueous chemical and biological co-contaminants containing heavy metals, antibiotics and antibiotic resistant bacteria (ARB) are harmful for the ecological environment. An innovative degradation-inactivation mechanism and a coupled homogeneous and heterogeneous Fenton-like system were proposed herein to synchronously decontaminate aqueous tetracycline (TC) and TC-resistant Salmonella typhi (TRST). Results showed that the homogeneous Cu(II)/PMS system, wherein, trace Cu(II) and TC co-existed to form cupric complexes that activated PMS, effectively caused TC degradation and TRST inactivation by Cu(III) oxidation. However, the inactivation efficiency was only ∼ 47 % in mono Cu(II)/PMS system because of the generation of limited radicals from the conversion of Cu(III). After the addition of Fe/N/S-doped biochar (Fe/N/S-BC) to Cu(Ⅱ)-TC-TRST ternary contaminants, the heterogeneous Fe/N/S-BC/PMS system superposed on the effect of homogeneous Cu(II)/PMS system by generating abundant reactive oxygen species (ROS) and promoting TC degradation and TRST inactivation. Despite the competition of Cu(II) and TC, the coupled homogeneous/heterogeneous Fenton-like system enhanced the inactivation of TRST increasing to ≥98 %. Both radical (•OH, •O2–etc) and nonradical (Cu(III) and 1O2) pathways participated in the synchronized decontamination of TC and TRST and its antibiotic resistant genes (ARGs) in Cu(II)-TC-TRST ternary contaminants.

Degradation of perfluorooctanoic acid (PFOA) using multiphase fenton-like technology by reduced graphene oxide aerogel (rGAs) combined with BDD electrooxidation

Perfluorooctanoic acid (PFOA) pollution in aqueous environments has attracted considerable attention. Due to its high chemical stability, PFOA is very difficult to degrade, posing potential risks to human health. Therefore, it is of significance to find an efficient and eco-friendly way to remove PFOA from the environment. In this study, reduced graphene oxide aerogel (rGA) was loaded with Fe3O4 and Cu nanoparticles (NPs) to obtain Fe3O4-rGA and Cu-rGA, which were then prepared into cathodes using the microbubble templating method. Heterogeneous Fenton-like system coupling Fe3O4/Cu-rGA cathodes and boron-doped diamond (BDD) electrodes were used to efficiently degrade PFOA in aqueous solutions. The parameters for PFOA degradation were optimized to be initial current density of 20.0 mA cm−2, initial electrolyte pH of 6, and electrolyte (Na2SO4) concentration of 10 mM. After 360 min, the Fe3O4-rGA and Cu-rGA systems achieved PFOA removal efficiencies of 98.25 % and 98.91 %, respectively, which were 16.7 % and 17.5 %, respectively, higher than that achieved by the system using a commercial graphite electrode. PFOA was completely removed, in 720 min and the F− production rates were 62.29 % and 65.48 % in the Fe3O4-rGA and Cu-rGA systems, respectively. PFOA degradation followed pseudo first-order kinetics in both systems (R2 > 0.99). The results of free radical quenching experiment and electrochemical performance experiment showed that the abundant active sites and excellent electrocatalytic properties of Fe3O4-rGA and Cu-rGAs promoted the formation of ⋅OH radicals for efficient PFOA degradation. In conclusion, coupling heterogeneous Fenton-like systems with Fe3O4 or Cu NPs-loaded rGA and BDD electrooxidation have great potential in the treatment of PFOA wastewaters in the future.

Facile synthesis of fine-grained CoFe2O4 anchored on porous carbon for simultaneous removal of tetracycline and arsenite via peroxymonosulfate activation

The coexistence of tetracycline (TC) and arsenite (As(III)) in livestock wastewater threatens public health, and the heterogeneous Fenton-like system is a practical approach for the simultaneous removal of TC and As(III). In this work, fine CoFe2O4 nanoparticles are facilely anchored on heretically porous carbon (CoFe2O4@PC) via a microwave-assisted calcination method and used for eliminating TC and As(III) via peroxymonosulfate (PMS) activation. The CoFe2O4@PC/PMS system exhibits excellent performance in the simultaneous removal of 96% of 10 mg/L TC and 86% of 50 μM As(III) within 30 min, whereas the porous carbon can boost the mass transfer efficiency and protect CoFe2O4 against Co and Fe ions leaching. The CoFe2O4@PC/PMS system maintains satisfactory activity and stability in a broad pH range (3–11) and anti-interference capacity (anions, humic acid and water matrices). Meanwhile, the CoFe2O4@PC with the strong magnetic property was readily recovered from the reaction solution. Moreover, the cooperation of radical (·OH, ·SO4- and ·O2–) and nonradical (1O2) pathways was documented to play critical roles in enhancing the oxidation of TC and As(III), which effectively reduces the toxicity of degradation intermediates. This work offers a facile strategy for constructing spinel-based catalysts and opens a broad prospect for removing TC and As(III) in livestock wastewater.

Concurrent mitigation and facile monitoring of xenobiotics by a highly efficient and recyclable nanoengineered catalyst

Recurrent waves of novel COVID-19 and its variants have resulted in the usage of antimicrobials to hitherto unprecedented levels, aggravating the threat of antibiotic-resistant pathogens. We devised a facile yet robust nano-bio-engineering strategy for the detection, mitigation, and degradation of tetracycline and erythromycin antibiotics in water bodies. The strategy includes magnetic single-walled carbon nanotubes (MSCN) based adsorption and degradation of these antibiotics. Antibiotics were detected and their degradation was monitored using bioengineered biosensors showing high specificity and sensitivity (1.33 and 51.24 ppb for tetracycline and erythromycin, respectively). The MSCN followed pseudo-second-order kinetics with >75% adsorption of antibiotics. The degradation efficiency of >93% in 4 h at pH 7 and 313 K was attained by adding H2O2, activating the heterogeneous Fenton-like reaction-based degradation system. The universality of this approach was proven by showing the degradation of other xenobiotics. This strategy manifests a novel approach for mitigating xenobiotics and their detrimental environmental effects.

Highly dispersed natural Goethite/Fe3O4 heterogeneous Fenton-like catalyst for efficient tetracycline degradation: Rapid accumulation of hydroxyl radicals by Fe–O–Si bonds

A highly dispersed catalyst (Fe3O4/NFe) was prepared with Fe3O4 and natural goethite (NFe) to remove TC in the heterogeneous Fenton-like system. A large amount of ≡Si–O–Si on NFe could be destroyed by the grinding method to produce ≡SiO• on the surface. Fe3O4 nanoparticles were successfully grown on the NFe with the formation of Fe–O–Si bonds, the Fe3O4/NFe retained the magnetic performance and the larger dispersion from predecessors. In the Fe3O4/NFe/H2O2 process, the degradation performance of tetracycline (TC) could reach 90.1% in 30 min. Moreover, the toxicity of TC and its intermediates was estimated in ECOSAR software. The ESR analysis and quenching experiments revealed the contribution of •OH, HO2•, and ≡SiO• in TC removal. A part of •OH, HO2• in solution could decompose TC, and the ≡SiO• on surface also directly remove TC. The strong interactions of Fe–O–Si bonds improved the generation of abundant •OH, and the total concentration of •OH by Fe3O4/NFe in 30 min is 244.7 μmol/L. In DFT analysis, the electrons redistribution between Fe3O4 and NFe could easily provide the electrons to activate H2O2, and improved the adsorption of H2O2 in Fe3O4/NFe/H2O2 system. The removal rate of TC still reached 73.3% by Fe3O4/NFe after five cycles. In the present work, this Fe3O4/NFe has been shown to be a promising alternative to traditional homogeneous Fenton method.

Heterogeneous Fenton-like Photocatalytic Process towards the Eradication of Tetracycline under UV Irradiation: Mechanism Elucidation and Environmental Risk Analysis

The problem of the deep elimination of antibiotics in environmental bodies is exceptionally warranted. In this work, a ternary nanocomposite of FeNi3/SiO2/CuS (FSC) was fabricated and then integrated with UV light irradiation and hydrogen peroxide as the heterogeneous Fenton-like photocatalytic system for the decomposition of tetracycline (TC) from aqueous media. During this process, various influencing parameters such as pH, catalyst dosage, initial content of TC, hydrogen peroxide (H2O2) dose, and operating time were explored. At optimized circumstances, i.e., 5 of pH, 10 mg/L of TC concentration, 150 mg/L of H2O2 dosage, and 200 min of degradation time, the elimination proportion of TC was 96%. The results of capture agent tests clarified that hydroxyl radical (HO•) played the predominant role in the photocatalytic decontamination of TC. Moreover, with the elevated contact time and content of H2O2, the efficiency of TC decontamination increased significantly. Additionally, the findings of the stability and reusability experiments of the fabricated nanocomposite showed that the percentage of TC removal decreased by only about 5% after six cycles. Furthermore, the photocatalytic mechanism of the decontamination of TC over the FSC photocatalyst was elucidated. Eventually, the non-carcinogenic risk analysis in the surface water sample was carried out using multiple photocatalytic processes for the first time. These outcomes obtained in this study validate that coupling the photocatalytic system and the H2O2 oxidation agent facilitates the elimination of a great variety of pharmaceutical contaminants from aqueous media.

Molecular structure-dependent contribution of reactive species to organic pollutant degradation using nanosheet Bi2Fe4O9 activated peroxymonosulfate

Iron-based catalysts have attracted increasing attention in heterogeneous activation of peroxymonosulfate (PMS). However, the activity of most iron-based heterogenous catalysts is not satisfactory for practical application and the proposed activation mechanisms of PMS by iron-based heterogenous catalyst vary case by case. This study prepared Bi2Fe4O9 (BFO) nanosheet with super high activity toward PMS, which was comparable to its homogeneous counterpart at pH 3.0 and superior to its homogeneous counterpart at pH 7.0. Fe sites, lattice oxygen and oxygen vacancies on BFO surface were believed to be involved in the activation of PMS. By using electron paramagnetic resonance (EPR), radical scavenging tests, 57Fe Mössbauer and 18O isotope-labeling technique, the generation of reactive species including sulfate radicals, hydroxyl radicals, superoxide and Fe (IV) were confirmed in BFO/PMS system. However, the contribution of reactive species to the elimination of organic pollutants very much depends on their molecular structure. The effect of water matrices on the elimination of organic pollutants also hinges on their molecular structure. This study implies that the molecular structure of organic pollutants governs their oxidation mechanism and their fate in iron-based heterogeneous Fenton-like system and further broadens our knowledge on the activation mechanism of PMS by iron-based heterogeneous catalyst.

A strategy of eliminating phosphate inhibiting the degradation of metronidazole by hydroxylamine assisted heterogeneous Fenton-like system

The heterogeneous Fenton-like process using hydroxylamine (HA) possessed the merit of rapid oxidation performance is very fascinating for water treatment. However, the existence of phosphate limits the oxidation rate of organic pollutants. This study uncovered the role of phosphate in HA-assisted Fenton-like process and provided a feasible strategy to dispel the negative influence of phosphate upon introduction of aluminum and ferric ions. Besides, optimized reaction conditions as nMET of 0.04 g/L, H2O2 of 1.3 mM and HA of 0.4 mM were acquired by response surface methodology (RSM) with MNZ degradation efficiency of 95.21% and leaching Fe ions of 2.26 mg/L. Hydroxyl radical (HO) and superoxide radical (O2−) were responsible for MNZ removal. Subsequently, the toxicities assessment of formed MNZ byproducts was clarified based on the analysis of MNZ decomposition pathways.

Construction lamellar BaFe12O19/Bi3.64Mo0.36O6.55 photocatalyst for enhanced photocatalytic activity via a photo-Fenton-like Mo6+/Mo4+redox cycle

The novel BaFe12O19/Bi3.64Mo0.36O6.55 composite materials were constructed as magnetically recyclable photo-Fenton-like degradation systems. The composite catalyst not only promoted the effective transfer of photo-generated electrons and improved the Mo6+/Mo4+ cycle consequent, but also activated hydrogen peroxide to generate oxidizing free radicals. BaFe12O19/Bi3.64Mo0.36O6.55–0.25 exhibited an outstanding degradation performance for tetracycline hydrochloride it is 1.3 times to Bi3.64Mo0.36O6.55. The thermal catalytic performance of the Bi3.64Mo0.36O6.55 monomer is similar to that of the BaFe12O19/Bi3.64Mo0.36O6.55 material without light. However, the removal rate of BaFe12O19/Bi3.64Mo0.36O6.55 material reaches 84.5% after 60 min with light, far exceeding that of Bi3.64Mo0.36O6.55 material. By way of the contrast experiment with light and without light, it is further demonstrated that interfacial interaction between BaFe12O19 and Bi3.64Mo0.36O6.55 acted a key role in the photocatalytic reaction system. It is also a good advantage that pollutants can be efficiently degraded without adjusting the pH. The characterization of photocurrent and X-ray photoelectron spectroscopy (XPS) also further proved the synergy between the two materials, which is useful to the separation of electrons and holes. The synergy ultimately improves the degradation performance. Besides, BaFe12O19/Bi3.64Mo0.36O6.55 can be easily separated by an external magnetic field after the photocatalytic activity reaction owing to BaFe12O19's magnetic properties. It provides a new research idea for the construction and iron-based heterogeneous Fenton-like system for magnetic degradation of antibiotics.

Novel urchin-like Co5Mn-LDH hierarchical nanoarrays: Formation mechanism and its performance in PMS activation and norfloxacin degradation

In this study, Co5Mn-layered double hydroxide (Co5Mn-LDH) was synthesized by hydrothermal process. The SEM image of Co5Mn-LDH shows the urchin-like sphere with the approximate diameter of 7.0–8.0 μm assembled by the numerous rods with a width of about 30–40 nm. Investigation on the formation mechanism of Co5Mn-LDH indicated that NH4F dosage and reaction time played an essential role in modulating the morphology and structure of Co5Mn-LDH. Co5Mn-LDH, as a heterogeneous Fenton-like catalyst, could efficiently activate peroxymonosulfate (PMS) and degrade norfloxacin (NOR) in the pH range of 3.0–9.0. The degradation efficiency of NOR was 98.7% at its natural pH, and the COD removal rate reached 83.3% within 8 min. On the one hand, the abundant Co2+ and Mn3+ in Co5Mn-LDH can simultaneously react with PMS to generate various reactive oxygen species (ROS), while the resulted Co3+ and Mn4+ could convert to original Co2+ and Mn3+, behaving similarly to the Harber-Weiss cycle. On the other hand, the regeneration of Co2+ could also rely on the oxidation and reduction between Co3+/Co2+ and Mn4+/Mn3+. Co(OH)6 octahedron structure and rich surface hydroxyl groups within LDH are favorable to the transformation between Co2+/Mn3+ and Co3+/Mn4+. Such mechanism provides new insights into the nature of reactions in heterogeneous Fenton-like system.

Copper-incorporated dendritic mesoporous silica nanospheres and enhanced chemical mechanical polishing (CMP) performance via Cu2+/H2O2 heterogeneous Fenton-like system

The structure-dependent properties of abrasive particles play an extremely important role in atomic and close-to-atomic scale manufacturing. In this work, copper-incorporated dendritic mesoporous silica (D-mSiO2) nanoparticles were fabricated via a simple synthesis strategy of solvothermal post-treatment approach. As revealed by XRD, FTIR, HAADF-STEM and the corresponding EDX elemental mapping, some Cu ions were converted into CuO nanocrystals, and others were incorporated into D-mSiO2 frameworks. High-resolution AFM confirmed that the Cu- modified D-mSiO2 abrasives afforded nearly defect-free and atomically planarized dielectric film surfaces with angstrom-level roughness, and at the same time, enabled a significant improvement in removal efficiency. The involved Cu2+-catalyzed heterogeneous Fenton-like reaction in the presence of H2O2 might be responsible for the productions of highly reactive species in polishing slurries, thus contributing to the hydration layer formation and the material removal enhancement. The developed Cu-modified D-mSiO2 material is an efficient candidate for functional abrasive systems with better surface planarization capacity and superior material removal rate. Furthermore, the Cu2+/H2O2 heterogeneous Fenton-like system can be expected to a promising method to supplement in existing free radical-assisted polishing.

Efficient Fe(III) reduction and persulfate activation induced by ligand-to-metal charge transfer under visible light enhances degradation of organics

Efficient transformation of Fe(III) to Fe(II) enhances the efficiency of persulfate-based Fenton-like process (e.g., Fe(II)-PS system). Here, we developed a novel heterogeneous Fenton-like system driven by visible light (organic-Fe(III)-PS-TiO2-Vis) for effective reduction of Fe(III), activation of PS and degradation of organic pollutants without the need for external reducing agents or modifications in TiO2. The visible light-induced ligand-to-metal (organic-to-TiO2) charge transfer (LMCT) remarkably boosting Fe(III) reduction to increase reactive oxygen species (ROS) via PS activation, and further enhanced the self-degradation and mineralization of various organics, including phenolics (bisphenol A and phenol), antibiotics (ibuprofen and tetracycline), and dyes (methylene bule and rhodamine B). Compared with traditional Fe(II)-PS and Fe(II)–H2O2 systems, the organic-Fe(III)-PS-TiO2-Vis process requires a lower dosage of iron salt. The effective pH range has been broadened to neutral conditions due to effective prevention of Fe(III) precipitation and rapid circulation of Fe(III)/Fe(II). The comprehensive mechanistic study indicated that a synergistic effect was generated via Fe(III) reduction, PS activation, ROS generation and organic decomposition, resulting in sustainable and excellent catalytic performance of this novel Fenton-like process. Further, the results of cycling experiments and tests involving real industrial wastewater highlight the enormous potential of the proposed LMCT-mediated heterogeneous Fenton-like process in environmental remediation.

Simple and green method for preparing copper nanoparticles supported on carbonized cotton as a heterogeneous Fenton-like catalyst

In this study, copper nanoparticles supported on carbonized cotton as a heterogeneous Fenton-like three-dimensional (3D) structure catalyst were constructed for catalytic degradation of polyvinyl alcohol (PVA), Rhodamine-B, and Reactive Red X-3B. Herein, cotton in natural fibers was used as a carbon source, which provides a new method for the preparation of catalysts supported by carbon materials. In copper@carbonized cotton nanoparticles (CCCNs), the carbon layer is produced during the calcination process, which not only enhances the conversion of Cu0 to Cu+/Cu2+, but also accelerates the electron transfer and promotes the catalytic decomposition of hydrogen peroxide (H2O2) to generate·OH radicals. In a wide pH range (3−7), the CCCNs/H2O2 system could effectively degrade PVA, and the removal rates of PVA and TOC were found to be 99.5% and 98.68%, respectively. The optimized experimental conditions are as follows: pH, 7; mass ratio of Cu(OH)2CO3 to cotton, 10:4; catalyst dosage, 2.6 g L−1; reaction temperature, 65 °C; H2O2 dosage, 0.16 g mL−1, and without adjusting pH. In addition to the high catalytic activity, CCCNs exhibited good stability and reusability due to the strong 3D carbon layer. The CCCN composite material has been proven to be ideal catalyst to enhance the removal rate of the heterogeneous Fenton-like reaction system in removing organic pollutants present in wastewater.

Preparation of BiFeO3 and photodegradation of tetracycline pollutant in the UV-heterogeneous Fenton-like system.

Surplus tetracycline in the water body causes damage to the ecology balance and human health. Therefore, this work established an efficient strategy, namely, the BFO-based UV-heterogeneous Fenton-like system, to eliminate TC pollution. The photocatalytic oxidation system has been integrated with the heterogeneous Fenton-like system, cooperated with the photolysis of H2O2. These synergistic effects could boost the generation of reactive species for the TC degradation and mineralization, due to the reduction of Fe(III) to Fe(II) by photogenerated electrons and the separation of photogenerated electron-hole pairs. The prepared BFO was stable with no secondary pollution, and could be recovered by an extra magnet to reuse. Compared with other single oxidation systems, this coupled system showed an outstanding performance in TC disposal, and TC and TOC removal efficiencies could reach 100% and 74.92%, respectively. Moreover, the mechanisms for TC degradation involved that TC was degraded by oxidation species, such as superoxide radicals, hydroxyl radicals, and positive holes, and intermediate products in the TC degradation process mainly were products at m/z = 459, m/z = 445, and m/z = 134. The promising TC disposal efficiency achieved by the integration between BFO-based photocatalytic and heterogeneous Fenton-like system sheds light on applying BFO to control water pollution.