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Magnetite nanoparticles (Fe3O4 NPs) are among the most effective Fenton-Like heterogeneous catalysts for degrading environmental contaminants. However, Fe3O4 NPs aggregate easily and have poor dispersion stability because of their magnetic properties, which seriously decrease their catalytic efficiency. In this study, a novel environmentally friendly method for synthesising Fe3O4@CA was proposed. Fe3O4 NPs were immobilized on the 3D cellulose aerogels (CAs) in order to augment the degradation efficiency of p-nitrophenol (PNP) treatment and make the separation of the catalyst accessible by vacuum filtration method. Besides, CAs were fabricated from a cellulose source extracted from water hyacinth by using different cross-linking agents, such as kymene (KM) and polyvinyl alcohol–glutaraldehyde system (PVA–GA), and other drying methods, including vacuum thermal drying and freeze drying, were evaluated in the synthesis process. As-synthesized samples were analysed by various methods, including Powder X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis and Brunauer–Emmett–Teller. Then, using ultraviolet–visible spectroscopy, the difference in the degradability of PNP of the obtained material samples was also investigated to determine their potential applications. Results highlighted that the Fe3O4-3@CA-KF catalyst with an Fe3O4 loading of 0.40 g/gCA used KM as a cross-linker and the freeze-drying method demonstrated the highest PNP removal efficiency (92.5 %) in all Fe3O4@CA samples with a H2O2 content of 5 g/L. The degradation kinetics and well-fitted pseudo-first-order model were investigated. Notably, after five successive PNP degradation experiments, this catalyst retained ∼80 % of the ability to degrade PNP, indicating its outstanding reusability. In environmental remediation, this study provides valuable insights into the development of simply separated and high-efficiency catalysts for heterogeneous catalytic reactions.

Plant polysaccharides exhibit many biological activities that are remarkably affected by molecular size and structures. This study aimed to investigate the degradation effect of ultrasonic-assisted Fenton reaction on the Panax notoginseng polysaccharide (PP). PP and its three degradation products (PP3, PP5, and PP7) were obtained from optimized hot water extraction and different Fenton reaction treatments, respectively. The results showed that the molecular weight (Mw) of the degraded fractions significantly decreased after treatment with the Fenton reaction. But the backbone characteristics and conformational structure were similar between PP and PP-degraded products, which was estimated by comparing monosaccharides composition, functional group signals in FT-IR spectra, X-ray differential patterns, and proton signals in 1H NMR. In addition, PP7, with an Mw of 5.89 kDa, exhibited stronger antioxidant activities in both the chemiluminescence-based and HHL5 cell-based methods. The results indicated that ultrasonic-assisted Fenton degradation might be used to improve the biological activities of natural polysaccharides by adjusting the molecular size. [ABSTRACT FROM AUTHOR]

Iron-containing MOFs have attracted extensive interest as promising Fenton-like catalysts. In this work, magnetic Fe 3 O 4 nanofiber (FNS)/MOFs composites with stable structure, included FNS/MIL-88B, FNS/MIL-88A and FNS/MIL-100, were prepared via the in-situ solvothermal method. The surface of the obtained fibers was covered by a dense and continuous MOFs layer, which could effectively solve the agglomeration problem of MOFs powder and improved the catalytic performance. The adsorption and catalytic properties of FNS/MOFs composites were evaluated by removal of norfloxacin. FNS/MIL-88B showed the best performance with a maximum adsorption capacity up to 214.09 mg/g, and could degrade 99% of NRF in 60 min. Meanwhile, FNS/MIL-88B had a saturation magnetization of 20 emu/g, and could be rapidly separated by an applied magnetic field. The self-supported nanofibers allowed the adequate contact between MOFs and pollutants, and promoted the catalytic activity and high stability. We believe that this work provided a new idea for the design and preparation of Fenton-like catalysts especially MOFs composites. [Display omitted] • A series of Fe 3 O 4 /MILs composite fibers were prepared by in-situ method. • The magnetic nanofibers could be used effectively for removal of organic contaminants. • FNS/MIL-88B exhibited a maximum adsorption capacity of 214.09 mg/g for NRF. • FNS/MIL-88B had a removal efficiency of 98% for NRF in 60 min by Fenton-like reaction. • FNS/MIL-88B could be easily separated and retained 86% of removal efficiency for NRF after 5 cycles. [ABSTRACT FROM AUTHOR]

Plant polysaccharides exhibit many biological activities that are remarkably affected by molecular size and structures. This study aimed to investigate the degradation effect of ultrasonic-assisted Fenton reaction on the Panax notoginseng polysaccharide (PP). PP and its three degradation products (PP3, PP5, and PP7) were obtained from optimized hot water extraction and different Fenton reaction treatments, respectively. The results showed that the molecular weight (Mw) of the degraded fractions significantly decreased after treatment with the Fenton reaction. But the backbone characteristics and conformational structure were similar between PP and PP-degraded products, which was estimated by comparing monosaccharides composition, functional group signals in FT-IR spectra, X-ray differential patterns, and proton signals in 1H NMR. In addition, PP7, with an Mw of 5.89 kDa, exhibited stronger antioxidant activities in both the chemiluminescence-based and HHL5 cell-based methods. The results indicated that ultrasonic-assisted Fenton degradation might be used to improve the biological activities of natural polysaccharides by adjusting the molecular size.

The application of microwave energy in the synthesis of catalytic materials has been indicated to induce desirable effects that lead to improved activity. Herein, bimetallic oxides immobilised on silica were prepared by incipient-wetness impregnation method and the resulting catalysts were subjected to microwave irradiation. The catalysts were characterised with X-ray diffraction, X-ray photoelectron spectroscopy and cyclic voltammetry. A comparison of the activities of the catalyst thermally treated in microwave oven with that thermally treated in conventional oven showed that the former exhibited superior performance. Microwave power and duration of irradiation had influence on the crystallite size of the catalysts which in turn had effect on their activities for heterogeneous Fenton degradation of methylene blue in aqueous solution. It was also observed that Fe/Mn ratio in the catalyst significantly affected its activity. The bimetallic catalyst was highly effective for the destruction of the target organic pollutant, with 97% of the dye degraded in 60 min at near neutral pH when the optimised catalyst was used. The material can be an attractive heterogeneous catalyst for Fenton decontamination of water containing harmful organic substances. [ABSTRACT FROM AUTHOR]

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Boric acid (H 3 BO 3) modified Bi 2 Fe 4 O 9 (H 3 BO 3 @Bi 2 Fe 4 O 9 , BBFO) materials were prepared by surface H 3 BO 3 treatment on Bi 2 Fe 4 O 9 (BFO) employing mechanical ball milling method. XPS analysis and FT-IR spectra demonstrates that H 3 BO 3 was successfully fastened on BFO surface through intense friction and collision between mixed powder (H 3 BO 3 and BFO) and abrasive. And EPR result illustrates that the more abundant oxygen vacancy (OVs) has been introduced into BFO surface in H 3 BO 3 modification process. The Fenton degradation rate for oxytetracycline (OTC) of BBFO-2 materials reaches 75.0 % within 60 min, which is 21.8 % higher than that of BFO treated by ball milling process without H 3 BO 3 modification (HBFO). And the H 2 O 2 utilization rate (23.4 %) of BBFO-2 materials is higher than that of HBFO (7.6 %), which ascribes to the H 3 BO 3 modification and the introduction of abundant OVs by the surface electrons accumulation and transfer for strengthening the Fe3+/Fe2+ cycle and H 2 O 2 decomposition. The possible degradation pathways and Fenton reaction mechanism was speculated by ESR and HPLC-MS analysis. The manuscript provides a scientific reference and theoretical basis for investigating the preparation and enhancement mechanism of surface modification strategy for Fe-based Fenton catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

A Fe-pillared montmorillonite (Fe-MMT) functionalized bio-based foam (Fe-MMT@CS/G) was developed by using chitosan (CS) and gelatin (G) as the matrix for high-efficiency elimination of organic pollutants through the integration of adsorption and Fenton degradation. The results showed that the mechanical properties of as-obtained foam were strengthened by the addition of certain amounts of Fe-MMT. Interestingly, Fe-MMT@CS/G displayed efficient adsorption ability for charged pollutants under a wide range of pH. The adsorption processes of methyl blue (MB), methylene blue (MEB) and tetracycline hydrochloride (TCH) on Fe-MMT@CS/G were well described by the Freundlich isotherm model and pseudo-second-order kinetic model. The maximum adsorption capacities were 2208.24 mg/g for MB, 1167.52 mg/g for MEB, and 806.31 mg/g for TCH. Electrostatic interactions, hydrogen bonding and van der Waals forces probably involved the adsorption process. As expected, this foam could exhibit better removal properties toward both charged and uncharged organic pollutants through the addition of H 2 O 2 to trigger the Fenton degradation reaction. For non-adsorbable and uncharged bisphenol A (BPA), the removal efficiency was dramatically increased from 1.20 % to 92.77 % after Fenton degradation. Additionally, it presented outstanding recyclability. These results suggest that Fe-MMT@CS/G foam is a sustainable and efficient green material for the alleviation of water pollution. [Display omitted] [ABSTRACT FROM AUTHOR]

XRD patterns of (a) Nd-Ce doped Fe 3 O 4 -chitosan (b) Fe 3 O 4 -chitosan. Nd-Ce doped Fe 3 O 4 -chitosan nanocomposite with a core–shell structure was prepared with the combination of a co-precipitation and a crosslinking method. The obtained magnetic nanocomposites were characterized systematically through the use of a UV–VIS, XRD, EDXA, SEM, FT-IR spectroscopy, TGA, Mass spectroscopy, TEM and an AGFM. The results revealed that the magnetic nanoparticles were spherical shaped with inverse spinel structure. The size of the nanoparticles were estimated 15 nm approximately. Magnetic measurement revealed that the saturation magnetization of the nanocomposite was 59.6 emu/g. It was found that the magnetic response and the catalytic activity of Fe 3 O 4 -chitosan nanocomposite increased when it doped with Nd+3 and Ce+3. The catalytic activity of Fe 3 O 4 -chitosan and Nd-Ce doped Fe 3 O 4 -chitosan nanocomposites were evaluated in Fenton degradation of Direct Red 81, and the degradation products were studied. The kinetic of degradation using Nd-Ce doped Fe 3 O 4 -chitosan was also investigated. Kinetic study revealed that the dye degradation obeyed pseudo-second-order Blanchard kinetic model. TGA results depicted the stability of Nd-Ce doped Fe 3 O 4 -chitosan nanocomposite in high temperatures. [ABSTRACT FROM AUTHOR]

Abstract Fe@Fe 2 O 3 core-shell nanowire is a promising heterogeneous Fenton iron catalyst to degrade organic pollutants. So far, the roles of hydroxylamine (HA) in Fe@Fe 2 O 3 /HA system for pollutant degradation still remain unknown. In this study, the HA-facilitated degradation of rhodamine B (RhB) and p-nitrophenol (PNP) by Fe@Fe 2 O 3 was reported and the underlying mechanisms were explored. Results show that addition of HA significantly enhanced degradation of organic pollutants and a higher HA dosage caused a faster degradation rate. The degradation process was completely inhibited by scavengers, indicating the hydroxyl radical (HO) from bulk solution dominated the reactions. HA in the Fe@Fe 2 O 3 /H 2 O 2 /HA system was highly efficient to promote the generation of HO by accelerating both the Fe3+/Fe2+ cycle and the H 2 O 2 decomposition. Meanwhile, HA itself was rapidly decomposed along with the pollutants degradation. About 50.5% of RhB and 46.4% of PNP were mineralized in the presence of HA. The effective pH value for degradation was expanded from 4.0 to 5.0. The EE/O calculations demonstrate that a higher energy input for PNP was required than that for RhB. This study will shed lights on the reactivity of the Fe@Fe 2 O 3 /HA system and provide an alternative pathway for removal of organic contaminants. Highlights • The HA-facilitated degradation of RhB and PNP by Fe@Fe 2 O 3 nanowires was reported. • The reactivity of the Fe@Fe 2 O 3 /HA system and the roles of HA were investigated. • HA in Fe@Fe 2 O 3 /HA system accelerated the Fe3+/Fe2+ cycle and H 2 O 2 decomposition. • EE/O calculations show a higher energy input for PNP was required than that for RhB. [ABSTRACT FROM AUTHOR]

In this work, FeM composites consisting of montmorillonite and variable amounts of Fe3O4 were successfully synthesized via a facile co-precipitation process. They were characterized using X-ray photoelectron spectroscopy (XPS), a field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDX), a transmission electron microscope (TEM), N2 adsorption–desorption, and Fourier transform infrared spectroscopy (FTIR) techniques to explain the effect of Fe3O4 content on the physicochemical properties of the Fe3O4–montmorillonite (FeM) composites. The FeM composites were subsequently used as heterogeneous Fenton catalysts to activate green oxidant (H2O2) for the subsequent degradation of ofloxacin (OFL) antibiotic. The efficiency of the FeM composites was studied by varying various parameters of Fe3O4 loading on montmorillonite, catalyst dosage, initial solution pH, initial OFL concentration, different oxidants, H2O2 dosage, reaction temperature, inorganic salts, and solar irradiation. Under the conditions of 0.75 g/L FeM-10, 5 mL/L H2O2, and natural pH, almost 81% of 50 mg/L of OFL was degraded within 120 min in the dark, while total organic carbon (TOC) reduction was about 56%. Although FeM composites could be a promising heterogeneous catalyst for the activation of H2O2 to degrade organic pollutants, including OFL antibiotic, the FeM-10 composite shows a significant drop in efficiency after five cycles, which indicates that more studies to improve this weakness should be conducted.

A hetero-Fenton catalyst comprising of Fe3O4 nanoparticles loaded on zeolite (FeZ) has been synthesized using a facile co-precipitation method. The catalyst was characterized using various characterization methods and then, subsequently, was used to degrade ofloxacin (OFL, 20 mg·L−1), an antibiotic, via a heterogeneous Fenton process in the presence of an oxidizing agent. The effects of different parameters such as Fe3O4 loading on zeolite, catalyst loading, initial solution pH, initial OFL concentration, different oxidants, H2O2 dosage, reaction temperature, and inorganic salts were studied to determine the performance of the FeZ catalyst towards Fenton degradation of OFL under different conditions. Experimental results revealed that as much as 88% OFL and 51.2% total organic carbon (TOC) could be removed in 120 min using the FeZ catalyst. Moreover, the FeZ composite catalyst showed good stability for Fenton degradation of OFL even after five cycles, indicating that the FeZ catalyst could be a good candidate for wastewater remediation.

Magnetite nanoparticles (Fe 3 O 4 NPs) are among the most effective Fenton-Like heterogeneous catalysts for degrading environmental contaminants. However, Fe 3 O 4 NPs aggregate easily and have poor dispersion stability because of their magnetic properties, which seriously decrease their catalytic efficiency. In this study, a novel environmentally friendly method for synthesising Fe 3 O 4 @CA was proposed. Fe 3 O 4 NPs were immobilized on the 3D cellulose aerogels (CAs) in order to augment the degradation efficiency of p -nitrophenol (PNP) treatment and make the separation of the catalyst accessible by vacuum filtration method. Besides, CAs were fabricated from a cellulose source extracted from water hyacinth by using different cross-linking agents, such as kymene (KM) and polyvinyl alcohol-glutaraldehyde system (PVA-GA), and other drying methods, including vacuum thermal drying and freeze drying, were evaluated in the synthesis process. As-synthesized samples were analysed by various methods, including Powder X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis and Brunauer-Emmett-Teller. Then, using ultraviolet-visible spectroscopy, the difference in the degradability of PNP of the obtained material samples was also investigated to determine their potential applications. Results highlighted that the Fe 3 O 4 -3@CA-KF catalyst with an Fe 3 O 4 loading of 0.40 g/g CA used KM as a cross-linker and the freeze-drying method demonstrated the highest PNP removal efficiency (92.5 %) in all Fe 3 O 4 @CA samples with a H 2 O 2 content of 5 g/L. The degradation kinetics and well-fitted pseudo-first-order model were investigated. Notably, after five successive PNP degradation experiments, this catalyst retained ∼80 % of the ability to degrade PNP, indicating its outstanding reusability. In environmental remediation, this study provides valuable insights into the development of simply separated and high-efficiency catalysts for heterogeneous catalytic reactions., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

A novel heterogeneous catalyst (TEA/GO@Fe 3 O 4 ) was synthesized by simple one-step hydrothermal method. Surprisingly, TEA/GO@Fe 3 O 4 showed an extremely fast decomposition rate for methylene blue (MB). According to the characterization results, the superior properties of the TEA/GO@Fe 3 O 4 can be attributed to following factors: (1) the application of GO prevents the agglomeration of Fe 3 O 4 nanoparticles, (2) the delocalized π electrons of GO and the lone pair electrons of triethanolamine and its oxidant products (TEA) promoted the regeneration of Fe 2+ , (3) the negative surface charge of TEA/GO@Fe 3 O 4 and the coordination between Fe and S can accelerate the diffusion rate of MB toward the surface of catalyst, (4) the prepared materials were superparamagnetic with a negligible coercivity and remanence, (5) the Fe 3 O 4 nanoparticles were immobilized on the surface of GO and functionalized by the TEA. Finally, the presumption mentioned above was proved by TEM, FTIR, XRD, XPS, Zeta potential and the degradation experiments. After the degradation reaction, the catalyst can be quickly separated by external magnetic field. Therefore, the TEA/GO@Fe 3 O 4 is a promising catalyst for the degradation of MB. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysts overcome the drawbacks of the homogeneous Fenton process, and have attracted considerable attention for degradation of organic pollutants in wastewater. In this study, a heterogeneous Fenton catalyst system was developed for the degradation of cationic dye by incorporating ferric oxide nanoparticles into modified diatomite composite. The catalyst was synthesized through two simple steps: firstly, the raw diatomite was modified by soaking into nitric acid; then, through forced hydrolysis strategy, the ferric oxide nanoparticles were incorporated into the pre-treated diatomite. The resultant catalyst were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. This novel diatomite Fe2 O3 catalyst demonstrated distinct catalytic activity and desirable efficiency for degradation of organic dye. Methylene Blue (MB) was completely decomposed within 20 min, and the decomposition efficiency was remained higher than 90% after 5 cycles of catalyst regeneration. The simplicity and low cost of the demonstrated catalytic material is promising for the efficient degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

Dyes pollution is one of the most serious environmental issues and has drawn increasing public concern. Nano-β-FeOOH can be used to remove dyes in wastewater. However its application is limited due to the problem of easy agglomeration and loss. In this paper, β-FeOOH was in-situ immobilized on a polydopamine (PDA) decorated ceramic ultrafiltration substrate (∼ 5 nm) to prepare a kind of ceramic supported loose composite nanofiltration membrane. The surface morphology and structure of the membranes were analyzed by FESEM, XPS, FTIR, XRD, and TG, which proved the construction of the PDA interlayer on the substrate and the successful in-situ formation of β-FeOOH film. Under the optimized preparation conditions (30 g L−1 FeCl 3 •6 H 2 O solution, 0.02 M HCl solution, 18 h mineralization time), the water flux of the obtained membrane is 38 L m−2 h−1 at 0.2 MPa with a dye rejection around 20%. Further, H 2 O 2 was added to activate the Fenton reactions of the immobilized β-FeOOH. Through the combined effects of loose nanofiltration and Fenton oxidation, the dyes removal reaches 98%. In long-term test, the removal of dyes is more than 97% after 6 cycles, and the prepared membrane can treat different kinds of dyes, indicating that the composite membrane has good stability. This research provides a simple way for preparing loose composite membrane with the function of Fenton degradation of dyes. It would have broad applications in industrial wastewater treatment. [Display omitted] • β-FeOOH was in-situ formed on a PDA decorated ceramic ultrafiltration substrate. • Combined loose nanofiltration and Fenton degradation of dye wastewater. • High efficiency and good stability of the membrane in dyes removal. [ABSTRACT FROM AUTHOR]

Nanoscale zero-valent iron (nZVI) incorporated with nanomagnetic diatomite (DE) composite material was prepared for catalytic degradation of methylene blue (MB) in heterogeneous Fenton system. The material was constructed by two facile steps: Fe3O4 magnetic nanoparticles were supported on DE by chemical co-precipitation method, after which nZVI was incorporated into magnetic DE by liquid-phase chemical reduction strategy. The as-prepared catalyst was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, magnetic properties measurement and nitrogen adsorption-desorption isotherm measurement. The novel nZVI@Fe3O4- diatomite nanocomposites showed a distinct catalytic activity and a desirable effect for degradation of MB. MB could be completely decolorized within 8 min and the removal efficiency of total organic carbon could reach to 90% after reaction for 1 h. [ABSTRACT FROM AUTHOR]

A major deficiency of the traditional Fenton technology in practical application is the production of a large amount of sludge. In this paper, we first synthesized a kind of magnetic alginate/PVA hydrogel microspheres by inverse emulsion method along with coprecipitation method. Through the cross-linking action of iron ions, sodium alginate and polyvinyl alcohol formed a stable interpenetrating network structure, in which the magnetic Fe 3 O 4 nanoparticles were stably wrapped. After drying, a novel alginate/PVA hydrogel-supported magnetic Fe 3 O 4 particles were obtained. FTIR,XRD，SEM and EDS were used to confirm the composition and structure of the composite material. Furthermore, the resultant alginate/PVA hydrogel-supported Fe 3 O 4 particles perform excellent broad-spectrum catalytic activity for Fenton degradation of organic dyes. Especially, compared with the classical Fenton catalyst, the double-crosslinked structure in the alginate/PVA hydrogel endows the magnetic Fe 3 O 4 particles with high stability and recyclability. After reuse for six times, the mass loss of the composite material is only 10 %, which can avoid the generation of iron sludge in Fenton-like reaction to the greatest extent. [Display omitted] [ABSTRACT FROM AUTHOR]

The activation of hydrogen peroxide (H 2 O 2) by Fe/carbon composites has been widely used for the removal of antibiotics. However, the secondary pollution of iron ions limits the application of Fe2+/H 2 O 2 system. In this work, three kinds of hydrogel materials combining metal-organic framework (MOF)-derived magnetic Fe/porous carbon (MagFePC) with sodium alginate (SA), polyacrylic acid (PAA) and agarose (AG) were prepared by different methods for removal of norfloxacin (NOR) antibiotics in simulated wastewater. After comparison, MagFePC/SA hydrogels synthesized by a titration forming method were found to have the advantages of good toughness, abundant pores and best Fenton activity. MagFePC/SA can effectively activate H 2 O 2 to remove NOR under neutral conditions, and there was almost no leaching of iron ions, causing no secondary pollution to the environment. The effects of pH, ionic strength and surfactants on the degradation performance for NOR were studied. Mechanism study revealed that ·O 2 − and 1O 2 were the main active species for the degradation of NOR, and the materials still had good stability and reusability after repeated cycles. More important, we built a simple automated unit for wastewater treatment under laboratory conditions that can completely degrade a 5 mg/L NOR solution at a flow rate of 2 mL/min. Current works showed that MagFePC/SA had the advantages of simple synthesis, outstanding degradability, excellent stability and eco-friendly reaction, which was a wastewater treatment material with good prospect for industrial application. [Display omitted] • Magnetic Fe/porous carbon/sodium alginate hydrogels were obtained by a titration forming method. • Fe species in hydrogels could activate H 2 O 2 to effectively remove norfloxacin (NOR). • Hydrogels limited the dissolution of irons and reduced the secondary pollution. • The degradation system achieved the automatic treatment of wastewater under laboratory conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • An iron-clay-cyclodextrin-polymer composite exhibits efficient removal of PFAS. • PFAS confinement on the catalytic surface enables effective oxidation by OH radicals. • Rapid oxidation and defluorination occur, achieving ∼ 73% mineralization of PFOA and PFOS. • Continuous catalytic activity is maintained over five consecutive oxidation cycles. The removal and oxidation of seven perfluorinated compounds were studied in the presence of an iron-clay-cyclodextrin polymer composite (Fe-MMT-βCD-DFB). The iron-clay backbone served as a heterogeneous Fenton catalyst, and the cyclodextrin polymer, cross-linked with polyfluorinated aromatic molecules, was used to promote removal and surface-confinement of the perfluorinated compounds. The composite exhibited superior adsorption (∼90%) and efficient oxidation (>70%) towards the high molecular weight PFAS: PFHpA, PFOA, PFNA, PFDA, and PFOS. The lower molecular weight PFAS: PFBA and PFHxA, showed lower adsorption affinity towards the composite but were almost completely degraded once adsorbed to the surface (>90%). The oxidation was very rapid, reaching over 65% degradation of PFOA and PFOS within the first 10 min. EPR and probe measurements revealed that hydroxyl radicals were responsible for the high degradation rates. In addition, fluoride ion measurements coupled with TOC and LC/MS analysis showed high defluorination and mineralization rates of PFOA and PFOS (73.2% and 73.5%, respectively). The composite also displayed excellent performance in a mixed solution with the seven different PFAS, especially towards the degradation of high MW compounds. Furthermore, the composite's degradation activity remained stable even after five cycles of adsorption and degradation. Taken together, the results suggest that composites that promote surface confinement of the pollutants near the catalytic active sites can be used to efficiently remove and destroy highly recalcitrant pollutants under benign environmental conditions. [ABSTRACT FROM AUTHOR]

All remediation pathways in aqueous solutions come down to three dominant ones - physical, chemical, and combinations thereof. Materials proposed for adsorption and oxidative degradation can induce positive or negative effects on cells compared to the pollutants themselves. Present research deals with the effects different methods for pesticide remediation have and how they impact cytotoxicity. With this particular intention, Fe-modified zeolites (obtained via citrate/oxalate complexes) of three zeotypes (MFI, BEA and FAU) were prepared and tested as adsorbents and Fenton catalysts for the removal of the acetamiprid pesticide. The materials are characterized by AFM, FTIR spectroscopy and ICP-OES. A different effect of the zeolite framework and modification route was found among the samples, which leads to pronounced adsorption (FAU), efficient Fenton degradation (MFI) or synergistic effect of both mechanisms (BEA). The cytotoxic effects of acetamiprid in the presence of zeolites, in pristine and modified forms, were tested on the MRC-5 human fibroblast cell line. A complete survey of the toxicity effect behind different pesticide removal methods is presented. Since neither adsorption nor catalytic degradation is the best option for pesticide removal, the focus is shifted to a combination of these methods, which proved to be optimal for pesticide toxicity reduction., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Water is a supreme requirement for the existence of life, the contamination from the point and non-point sources are creating a great threat to the water ecosystem. Advance tools and techniques are required to restore the water quality and metal-organic framework (MOFs) with a tunable porous structure, striking physical and chemical properties are an excellent candidate for it. Fe-based MOFs, which developed rapidly in recent years, are foreseen as most promising to overcome the disadvantages of traditional water depolluting practices. Fe-MOFs with low toxicity and preferable stability possess excellent performance potential for almost all water remedying techniques in contrast to other MOF structures, especially visible light photocatalysis, Fenton, and Fenton-like heterogeneous catalysis. Fe-MOFs become essential tool for water treatment due to their high catalytic activity, abundant active site and pollutant-specific adsorption. However, the structural degradation under external chemical, photolytic, mechanical, and thermal stimuli is impeding Fe-MOFs from further improvement in activity and their commercialization. Understanding the shortcomings of structural integrity is crucial for large-scale synthesis and commercial implementation of Fe-MOFs-based water treatment techniques. Herein we summarize the synthesis, structure and recent advancements in water remediation methods using Fe-MOFs in particular more attention is paid for adsorption, heterogeneous catalysis and photocatalysis with clear insight into the mechanisms involved. For ease of analysis, the pollutants have been classified into two major classes; inorganic pollutants and organic pollutants. In this review, we present for the first time a detailed insight into the challenges in employing Fe-MOFs for water remediation due to structural instability. [Display omitted] • Strategies of designing and synthesis of Fe-MOFs are reviewed. • Fe-MOFs utilization in organic pollutant removal is reviewed. • Mechanisms involved in the Fe-MOFs based water treatment are discussed. • The structural integrity of Fe-MOFs, challenges and possible research perspectives are provided. [ABSTRACT FROM AUTHOR]

Taking inspirations from nature, we endeavor to develop catalytically self-propelled nanojets from a type of tubular clay minerals, halloysite nanotubes (HNTs), and utilize them as catalysts targeted for catalysis where the traditional means of mechanical agitation cannot be implemented. Nanojets of Fe 3 O 4 @HNTs/Pt were prepared by impregnating platinum nanoparticles (Pt NPs) in lumens of HNTs and selective grafting of magnetite (Fe 3 O 4 ) particles on the external surface. The HNT-based nanojets were validated to be highly suitable both in free bulk solution and in microfluidic flow. An example of Fenton degradation catalyzed by these jets was demonstrated. The powerful movement of Fe 3 O 4 @HNTs/Pt (368 ± 50 μm·s -1 ) fueled by 5.0% wt. H 2 O 2 was found to follow a bubble propulsion mechanism, and the motion exhibits collective behavior as swarms. The clay tubes were for the first time observed to self-assemble into fish-like aggregates during swimming, reflecting natural occurrence of motion-evolution philosophy. Guided motion was realized by employing magnetic manipulation which makes jets feasible for reactors with complex microchannels/reactors.

In this work, FeM composites consisting of montmorillonite and variable amounts of Fe3O4 were successfully synthesized via a facile co-precipitation process. They were characterized using X-ray photoelectron spectroscopy (XPS), a field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDX), a transmission electron microscope (TEM), N2 adsorption–desorption, and Fourier transform infrared spectroscopy (FTIR) techniques to explain the effect of Fe3O4 content on the physicochemical properties of the Fe3O4–montmorillonite (FeM) composites. The FeM composites were subsequently used as heterogeneous Fenton catalysts to activate green oxidant (H2O2) for the subsequent degradation of ofloxacin (OFL) antibiotic. The efficiency of the FeM composites was studied by varying various parameters of Fe3O4 loading on montmorillonite, catalyst dosage, initial solution pH, initial OFL concentration, different oxidants, H2O2 dosage, reaction temperature, inorganic salts, and solar irradiation. Under the conditions of 0.75 g/L FeM-10, 5 mL/L H2O2, and natural pH, almost 81% of 50 mg/L of OFL was degraded within 120 min in the dark, while total organic carbon (TOC) reduction was about 56%. Although FeM composites could be a promising heterogeneous catalyst for the activation of H2O2 to degrade organic pollutants, including OFL antibiotic, the FeM-10 composite shows a significant drop in efficiency after five cycles, which indicates that more studies to improve this weakness should be conducted. [ABSTRACT FROM AUTHOR]

A hetero-Fenton catalyst comprising of Fe3O4 nanoparticles loaded on zeolite (FeZ) has been synthesized using a facile co-precipitation method. The catalyst was characterized using various characterization methods and then, subsequently, was used to degrade ofloxacin (OFL, 20 mg·L−1), an antibiotic, via a heterogeneous Fenton process in the presence of an oxidizing agent. The effects of different parameters such as Fe3O4 loading on zeolite, catalyst loading, initial solution pH, initial OFL concentration, different oxidants, H2O2 dosage, reaction temperature, and inorganic salts were studied to determine the performance of the FeZ catalyst towards Fenton degradation of OFL under different conditions. Experimental results revealed that as much as 88% OFL and 51.2% total organic carbon (TOC) could be removed in 120 min using the FeZ catalyst. Moreover, the FeZ composite catalyst showed good stability for Fenton degradation of OFL even after five cycles, indicating that the FeZ catalyst could be a good candidate for wastewater remediation. [ABSTRACT FROM AUTHOR]

• The reactivation process in low voltage electric field has been designed. • The cyclic catalytic performance of catalyst enhanced by the reactivation process. • The reactivation supplemented the surface electrons of recovery catalysts. Some Fenton Fe 3 O 4 catalysts have the problem that the catalytic performance gradually weakens with increasing number of cycles, which brings economic losses and treatment difficulties to industrial wastewater treatment. In this work, the cyclic catalytic performance of Fenton N-rGO/Fe 3 O 4 NPs catalysts for methylene blue (MB) has been enhanced by the reactivation process under the electric field. The effects of chemical reactions, voltage and electrolytic time on the cyclic performance of Fenton catalysts during the reactivation were discussed in detail. The first and fourth complete degradation of MB by fresh catalysts need 10 min and 20 min. After 2 h of reactivation using H 2 O as electrolyte at 1.0 V, the fourth complete degradation of MB only took 10 min. Zeta potential and CV curves showed that recovered catalyst has supplemented with surface electrons during the reactivation process. Characterizations demonstrated that the structure and composition of catalyst would not be influenced during the reactivation process. In short, the reactivation process under low voltage electric field is of great significance to Fenton Fe 3 O 4 catalysts in the field of industrial water treatment. [ABSTRACT FROM AUTHOR]

Acetylation has been shown to delay fungal decay, but the underlying mechanisms are poorly understood. Brown-rot fungi, such as Rhodonia placenta (Fr.) Niemelä, K.H. Larss. & Schigel, degrade wood in two steps, i.e., oxidative depolymerization followed by secretion of hydrolytic enzymes. Since separating the two degradation steps has been proven challenging, a new sample design was applied to the task. The aim of this study was to compare the expression of 10 genes during the initial decay phase in wood and wood acetylated to three different weight percentage gains (WPG). The results showed that not all genes thought to play a role in initiating brown-rot decay are upregulated. Furthermore, the results indicate that R. placenta upregulates an increasing number of genes involved in the oxidative degradation phase with increasing WPG. [ABSTRACT FROM AUTHOR]

Iron-clay-cyclodextrin composites were designed as sorbent catalysts to adsorb and oxidize pollutants from water. The clay-iron backbone served as a mechanical support and as a heterogeneous Fenton catalyst, and the cyclodextrin monomers or polymers cross-linked with polyfluorinated aromatic molecules were used to accommodate adsorption of the pollutants. The composite based on iron-clay-cyclodextrin-polymers (Fe-MMT-βCD-DFB) exhibited superior adsorption and degradation of the model pollutants, bisphenol A (BPA), carbamazepine (CBZ), and perfluorooctanoic acid (PFOA), compared to the monomer-based composite and the native iron clay. The variety of adsorption sites, such as the polyfluorinated aromatic cross-linker, cyclodextrin toroid, and iron-clay surface, resulted in high adsorption affinity toward all pollutants; BPA was primarily adsorbed to the cyclodextrin functional groups, CBZ showed high affinity toward the Fe-MMT surface and the Fe-MMT-βCD-DFB composite, whereas PFOA was adsorbed mainly to the βCD-DFB polymer. Degradation, using H 2 O 2 , was highly efficient, reaching over 90% degradation in 1 h for BPA and CBZ and ∼80% for PFOA. The composite also showed excellent degradation efficiency in a multicomponent system with all three model pollutants. Furthermore, the composite's activity remained steady for five consecutive cycles of adsorption and degradation. The ability to remediate a broad range of pollutants, and the high overall removal exhibited by this novel material, demonstrates the potential for future application in water remediation technologies.