Magnetic field assisted Fenton reactions for the enhanced degradation of methyl blue

Magnetic field was tentatively introduced into Fenton reactions system for the degradation and discoloration of methyl blue as the represent of organic chemical dye, which was a bio-refractory organic pollutant in industry wastewater. It was found that under optimal Fenton reaction conditions, with the assistant of magnetic field in Fenton reactions, the degradation rate of methyl blue, the decomposition rate of H2O2 and the conversion rate of Fe^2＋ were accelerated, the extent of them would be improved by the increase of magnetic field intensity. Meanwhile, the mineralization of methyl blue （CODer） was improved by over 10% with magnetic field.

Interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials： A review

The heterogeneous Fenton reaction can generate highly reactive hydroxyl radicals（·OH）from reactions between recyclable solid catalysts and H2O2 at acidic or even circumneutral pH.Hence,it can effectively oxidize refractory organics in water or soils and has become a promising environmentally friendly treatment technology.Due to the complex reaction system,the mechanism behind heterogeneous Fenton reactions remains unresolved but fascinating,and is crucial for understanding Fenton chemistry and the development and application of efficient heterogeneous Fenton technologies.Iron-based materials usually possess high catalytic activity,low cost,negligible toxicity and easy recovery,and are a superior type of heterogeneous Fenton catalysts.Therefore,this article reviews the fundamental but important interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials..OH,hydroperoxyl radicals/superoxide anions（HO2./O2^-.）and high-valent iron are the three main types of reactive oxygen species（ROS）,with different oxidation reactivity and selectivity.Based on the mechanisms of ROS generation,the interfacial mechanisms of heterogeneous Fenton systems can be classified as the homogeneous Fenton mechanism induced by surface-leached iron,the heterogeneous catalysis mechanism,and the heterogeneous reaction-induced homogeneous mechanism.Different heterogeneous Fenton systems catalyzed by characteristic iron-based materials are comprehensively reviewed.Finally,related future research directions are also suggested.

Fe_(2)O_(3)/TiO_(2)/reduced graphene oxide-driven recycled visible-photocatalytic Fenton reactions to mineralize organic pollutants in a wide pH range

Photocatalytic Fenton reactions combined the advantages from both photocatalysis and Fenton reaction in mineralizing organic pollutants. The key problems are the efficiency and recycling stability. Herein, we reported a novel Fe_(2)O_(3)/TiO_(2)/reduced graphene oxide(FTG) nanocomposite synthesized by a facile solvothermal method. The TiO_(2)in FTG degraded organic pollutants and mineralized intermediates via photocatalysis under visible light irradiation, which could also promote Fenton reaction by accelerating Fe^(3+)-Fe^(2+)recycle. Meanwhile, the Fe_(2)O_(3)rapidly degraded organic pollutants via Fenton reactions, which also promoted photocatalysis by enhancing visible light absorbance and diminishing photoelectronhole recombination. The high distribution of TiO_(2)and Fe_(2)O_(3)on rGO, together with their strong interaction resulted in enhanced synergetic cooperation between photocatalysis and Fenton reactions, leading to the high mineralization efficiency of organic pollutants. More importantly, it could also inhibit the leaching of Fe species, leading to the long lifetime of FTG during photocatalytic Fenton reactions in a wide pH range from 3.4 to 9.2.

Fenton reactions drive nucleotide and ATP syntheses in cancer

We present a computational study of tissue transcriptomic data of 14 cancer types to address： what may drive cancer cell division？ Our analyses point to that persistent disruption of the intraceUular pH by Fenton reactions may be at the root of cancer development. Specifically, we have statistically demonstrated that Fenton reactions take place in cancer cytosoi and mitochondria across all the 14 cancer types, based on cancer tissue gene-expression data integrated via the Michaelis-Menten equation. In addition, we have shown that （i） Fenton reactions in cytosol of the disease cells will continuously increase their pH, to which the cells respond by generating net protons to keep the pH stable through a combination of synthesizing glycolytic ATPs and consuming them by nucleotide syntheses, which may drive cell division to rid of the continuously synthesized nucleotides; and （ii） Fenton reactions in mitochondria give rise to novel ways for ATP synthesis with electrons ultimately coming from H2O2, largely originated from immune cells. A model is developed to link these to cancer development, where some mutations may be selected to facilitate cell division at rates dictated by Fenton reactions.

Oxygen vacancy boosting Fenton reaction in bone scaffold towards fighting bacterial infection

Bacterial infection is a major issue after artificial bone transplantation due to the absence of antibacterial function of bone scaffold,which seriously causes the transplant failure and even amputation in severe cases.In this study,oxygen vacancy(OV)defects Fe-doped Ti O2(OV-FeTiO2)nanoparticles were synthesized by nano TiO2and Fe3O4via high-energy ball milling,which was then incorporated into polycaprolactone/polyglycolic acid(PCLGA)biodegradable polymer matrix to construct composite bone scaffold with good antibacterial activities by selective laser sintering.The results indicated that OV defects were introduced into the core/shell-structured OV-FeTiO2nanoparticles through multiple welding and breaking during the high-energy ball milling,which facilitated the adsorption of hydrogen peroxide(H2O2)in the bacterial infection microenvironment at the bone transplant site.The accumulated H2O2could amplify the Fenton reaction efficiency to induce more hydroxyl radicals(·OH),thereby resulting in more bacterial deaths through·OH-mediated oxidative damage.This antibacterial strategy had more effective broad-spectrum antibacterial properties against Gram-negative Escherichia coli(E.coli)and Gram-positive Staphylococcus aureus(S.aureus).In addition,the PCLGA/OV-FeTiO2scaffold possessed mechanical properties that match those of human cancellous bone and good biocompatibility including cell attachment,proliferation and osteogenic differentiation.

Catalytic degradation of methylene blue by Fenton like system: model to the environmental reaction

To develop more efficient chemical methods for the demineralization of organic pollutants from water bodies, which one was also mimic to the nature, a degradation of methylene blue by Fe(Ⅲ) and H 2O 2 in the absence of light instead of Fe(Ⅱ) and H 2O 2 was studied. Results showed that use of Fe (Ⅲ) is more promising than Fe(Ⅱ). The present study reflects that Fenton reaction is more efficient, in the presence of a small amount of salicylic acid is added which is a one of the priority pollutant.

Enhanced Fenton,photo-Fenton and peroxidase-like activity and stability over Fe_3O_4/g-C_3N_4 nanocomposites

We prepared the Fe3O4/g‐C3N4nanoparticles(NPs)through a simple electrostatic self‐assembly method with a3:97weight ratio to investigate their Fenton,photo‐Fenton and oxidative functionalities besides photocatalytic functionality.We observed an improvement of the Fenton and photo‐Fenton activities of the Fe3O4/g‐C3N4nanocomposites.This improvement was attributed to efficient charge transfer between Fe3O4and g‐C3N4at the heterojunctions,inhibition of electron‐hole recombination,a high surface area,and stabilization of Fe3O4against leaching by the hydrophobic g‐C3N4.The obtained NPs showed a higher degradation potential for rhodamine B(RhB)dye than those of Fe3O4and g‐C3N4.As compared to photocatalysis,the efficiency of RhB degradation in the Fenton and photo‐Fenton reactions was increased by20%and90%,respectively.Additionally,the horseradish peroxidase(HRP)activity of the prepared nanomaterials was studied with3,3,5,5‐tetramethylbenzidinedihydrochloride(TMB)as a substrate.Dopamine oxidation was also examined.Results indicate that Fe3O4/g‐C3N4nanocomposites offers more efficient degradation of RhB dye in a photo‐Fenton system compared with regular photocatalytic degradation,which requires a long time.Our study also confirmed that Fe3O4/g‐C3N4nanocomposites can be used as a potential material for mimicking HRP owing to its high affinity for TMB.These findings suggest good potential for applications in biosensing and as a catalyst in oxidation reactions.

Treatment of pharmaceutical wastewater containing recalcitrant compounds in a Fenton-coagulation process

The advanced treatment using integrated Fenton＇s reaction and coagulation process was investigated in this study. Before the advancement, the pharmaceutical wastewater containing lincomycin hydrochloride was pretreated by UASB （upflow anaerobic sludge bed） and a SBR （sequencing batch reactor） process. The residual recalcitrant compounds, measured by gas chromatographymass spectrometry （GC-MS）, mainly consisted of alcohols, phenols, and nitrogenous and sulfur compounds. The experimental results indicated that when the Fenton＇s reaction was conducted at pH=3.0, H2O2CODOcr=0.27, H2O2/Fe^2＋=3：1 and 30 min of reaction time, and the coagulation process operated at a sulfate aluminum concentration of 800 mg/L and pH value of 5.0, the color and COD in the wastewater decreased by 94% and 73%, respectively; with a finale COD concentration of 267 mg/L and color level of 40 units, meeting the secondary standard of GB8978-1996 for industrial wastewater.

Mechanism of Photo-Fenton Degradation of Ethanol and PVA

Contrast degradation experiments between ethanol and polyvinyl alcohol (PVA) were conducted during H2O2, UV/H2O2, Fenton, and Photo-Fenton processes in this study. UV/VIS spectra showed' that complexes between Fe(Ⅲ) and organics were easily formed and degraded within reaction time. Compared with ,the degradation of complex, hydroxyl radicals acted weakly in Fenton or Photo-Fenton process. Hydroxyl radi'cals involved in Photo-Fenton process were deemed to be generated from the split decomposition of H2O2, photolysis of Fe_aq^3+, and degradation of hydrated Fe(Ⅳ)-complex but not traditional Fenton reaction. Experimental evidence to support this point was presented in this paper.

Different Heterogeneous Fenton Reaction Based on Foam Carrier Loaded with Photocatalysts

The effect of heterogeneous Fenton reaction was studied on methylene blue（MB） and Nitrosomonas europaea（N. europaea） cells. Four Fenton systems were prepared and compared with each other, including Nickel Foam（NF）/TiO2, NF/Bi2WO6, Ceramic foam（CM）/TiO2, and CM/Bi2WO6. The order of effect of fenton reaction ranked as NF/TiO2〉CM/TiO2〉NF/Bi2WO6〉CM/Bi2WO6. In acid or alkaline solution, the removal efficiency also decreased compared with neutral solution. With lower p H values, the nanoparticles were easier to break off from NF skeleton. Thus the synergetic effect of photocatalysis and fenton reaction can not take action. As for CM skeleton, the bond –Si-O-can bind with TiO2 or Bi2WO6. The membrane fluidity was used as an indicating parameter. After being treated by Fenton reaction, N. europaea surface was rougher than the native bacterium and the bulges on cell surface became irregular, which is attributed to change of lipopolysaccharide patches. Polarization of N. europaea cell membrane in acid medium increased more obvious than alkaline medium.

A Novel and Convenient Assay for the Determination of OH Produced by Fenton Reaction

A novel, simple and convenient method for the determination of hydroxyl radicals isestablished. Hydroxyl radicals produced by Fenton reaction is trapped by spin trap reagent phenyl-t-butyl nitrone (PBN), and the free radical adduct of PBN can be detected by single sweeposcillopolarography, with its second order derivative cathodic wave at -0.52V vs SCE. Theoptimum experimental conditions for the detemination is discussed, and the scavenging effects ofsome compounds on OH was also studied.

Effects of ultrasound-assisted Fenton treatment on structure and hypolipidemic activity of apricot polysaccharides

In order to improve the hypolipidemic activity of apricot polysaccharide,the methods of modifying polysaccharide were preliminarily screened,and the modification process conditions were further optimized by response surface methodology.Subsequently,the structure characterization and hypolipidemic activity of polysaccharide obtained by ultrasound-assisted Fenton treatment(EAP-UF)were studied.The results of Box-Behnken design indicated that under the optimal conditions of ultrasound-assisted Fenton degradation,the binding rate of sodium taurocholate and sodium glycocholate were 62.10%and 59.87%,respectively.Furthermore,the molecular weight,particle size,PDI value and roughness of EAP-UF decreased obviously,while the contents of hydroxyl,carbonyl carboxyl and rhamnose increased obviously.What's more,EAP-UF could significantly reduce the content of fat accumulation,triglyceride and total cholesterol in Caenorhabditis elegans.Taken together,ultrasound-assisted Fenton treatment is an effective method to enhance the hypolipidemic activity of polysaccharides.

Boosting Chemodynamic Therapy by the Synergistic Effect of Co‑Catalyze and Photothermal Effect Triggered by the Second Near‑Infrared Light

In spite of the tumor microenvironments responsive cancer therapy based on Fenton reaction(i.e.,chemodynamic therapy,CDT)has been attracted more attentions in recent years,the limited Fenton reaction efficiency is the important obstacle to further application in clinic.Herein,we synthesized novel FeO/MoS2 nanocomposites modified by bovine serum albumin(FeO/MoS2-BSA)with boosted Fenton reaction efficiency by the synergistic effect of co-catalyze and photothermal effect of MoS2 nanosheets triggered by the second near-infrared(NIR II)light.In the tumor microenvironments,the MoS2 nanosheets not only can accelerate the conversion of Fe3+ions to Fe2+ions by Mo4+ions on their surface to improve Fenton reaction efficiency,but also endow FeO/MoS2-BSA with good photothermal performances for photothermal-enhanced CDT and photothermal therapy(PTT).Consequently,benefiting from the synergetic-enhanced CDT/PTT,the tumors are eradicated completely in vivo.This work provides innovative synergistic strategy for constructing nanocomposites for highly efficient CDT.

Removal of phenol by activated alumina bed in pulsed high-voltage electric field

A new process for removing the pollutants in aqueous solution-activated alumina bed in pulsed high-voltage electric field was investigated for the removal of phenol under different conditions. The experimental results indicated the increase in removal rate with increasing applied voltage, increasing pH value of the solution, aeration, and adding Fe^2＋. The removal rate of phenol could reach 72.1% when air aeration flow rate was 1200 ml/min, and 88.2% when 0.05 mmol/L Fe^2＋ was added into the solution under the conditions of applied voltage 25 kV, initial phenol concentration of 5 mg/L, and initial pH value 5.5. The addition of sodium carbonate reduced the phenol removal rate. In the pulsed high-voltage electric field, local discharge occurred at the surface of activated alumina, which promoted phenol degradation in the thin water film. At the same time, the space-time distribution of gas-liquid phases was more uniform and the contact areas of the activated species generated from the discharge and the pollutant molecules were much wider due to the effect of the activated alumina bed. The synthetical effects of the pulsed high-voltage electric field and the activated alumina particles accelerated phenol degradation.

Degradation of Acid Orange 7 in an Atmospheric-Pressure Plasma-Solution System(Gliding Discharge)

In this work, a plasma-solution system was applied to the degradation of Acid Orange 7 （AO？）. The effects of initial concentration and type of feed gases （air, oxygen, nitrogen or argon） were studied. As the initial concentration increased from 100 mg/L to 160 mg/L, the discolouration rate of AO7 decreased from 99.3% to 95.9%, whereas the COD removal rate decreased from 37.9% to 22.6%. Air provided the best discolouration and COD removal rates （99.3% and 3？.9%, respectively）. In the presence of a zero-valent iron （ZVI） catalyst, the AO？ COD removal rate increased to 76.4%. The degradation products were analysed by a GC-MS, revealing that the degradation of the dye molecule was initiated through the cleavage of the -N=N- bond before finally being converted to organic acids.

Nitrogen-doped titanium dioxide/schwertmannite nanocomposites as heterogeneous photo-Fenton catalysts with enhanced efficiency for the degradation of bisphenol A

Potential health risks related to environmental endocrine disruptors(EEDs)have aroused research hotspots at the forefront of water treatment technologies.Herein,nitrogen-doped titanium dioxide/schwertmannite nanocomposites(N-TiO_(2)/SCH)have been successfully developed as heterogeneous catalysts for the degradation of typical EEDs via photo-Fenton processes.Due to the sustainable Fe(Ⅲ)/Fe(Ⅱ)conversion induced by photoelectrons,as-prepared N-TiO_(2)/SCH nanocomposites exhibit much enhanced efficiency for the degradation of bisphenol A(BPA;ca.100% within 60 min under visible irradiation)in a wide pH range of 3.0-7.8,which is significantly higher than that of the pristine schwertmannite(ca.74.5%)or N-TiO_(2)(ca.10.8%).In this photo-Fenton system,the efficient degradation of BPA is mainly attributed to the oxidation by hydroxyl radical(·OH)and singlet oxygen(^(1)O_(2)).Moreover,the possible catalytic mechanisms and reaction pathway of BPA degradation are systematically investigated based on analytical and photoelectrochemical analyses.This work not only provides a feasible means for the development of novel heterogeneous photo-Fenton catalysts,but also lays a theoretical foundation for the potential application of mineral-based materials in wastewater treatment.

Honeycomb-like biochar framework coupled with Fe_(3)O_(4)/FeS nanoparticles as efficient heterogeneous Fenton catalyst for phenol degradation

Achieving an efficient and stable heterogeneous Fenton reaction over a wide pH range is of great significance for wastewater treatment.Here,a pollen-derived biochar catalyst with a unique honeycomb-like structure,coupled with the dispersion of magnetic Fe_(3)O_(4)/FeS(Fe/S)nanoparticles,was synthesized by simple impregnation precursor,followed by pyrolysis.The prepared Fe/S-biochar catalyst demonstrated outstanding phenol degradation efficiency across a wide pH range,with 98%of which eliminated even under neutral conditions(pH 7.0).The high catalytic activity was due to the multilevel porous structure of pollenderived biochar provided enough active sites and allowed for better electron transfer,then increases oxidation ability to promote the reaction.Moreover,the acid microenvironment formed by SO_(4)^(2-)group from Fe/S composite extended the pH range for Fenton reaction,and S^(2-)facilitated the conversion of≡Fe^(3+)to≡Fe^(2+),resulting in remarkable degradation efficiency.Further,biochar can effectively promote cycling stability by limiting Fe leaching.This work may provide a general strategy for designing 3D framework biochar-based Fe/S catalysts with excellent performance for heterogeneous Fenton reactions.

Efficient Fe（Ⅲ）/Fe（Ⅱ） cycling triggered by MoO2 in Fenton reaction for the degradation of dye molecules and the reduction of Cr（Ⅵ）

There is a relatively low efficiency of Fe(Ⅲ)/Fe(Ⅱ) conversion cycle and H2 O2 decomposition(<30%) in conventional Fenton process,which further results in a low production efficiency of ·OH and seriously restricts the application of Fenton.Herein,we report that the commercial MoO2 can be used as the cocatalyst in Fenton process to dramatically accelerate the oxidation of Lissamine rhodamine B(L-RhB),where the efficiency of Fe(Ⅲ)/Fe(Ⅱ) cycling is greatly enhanced in the Fenton reaction meanwhile.And the L-RhB solution could be degraded nearly 100% in 1 min in the MoO2 cocatalytic Fenton system under the optimal reaction condition,which is apparently better than that of the conventional Fenton system(~50%).Different from the conventional Fenton reaction where the ’OH plays an important role in the oxidation process,it shows that 1 O2 contributes most in the MoO2 cocatalytic Fenton reaction.However,it is found that the exposed Mo^4+ active sites on the surface of MoO2 powders can greatly promote the rate-limiting step of Fe^3+/Fe^2+ cycle conversion,thus minimizing the dosage of H2 O2(0.400 mmol/L) and Fe^2+(0.105 mmol/L).Interestingly,the MoO2 cocatalytic Fenton system also exhibits a good ability for reducing Cr(Ⅵ) ions,where the reduction ability for Cr(Ⅵ) reaches almost 100% within 2 h.In short,this work shows a new discovery for M002 cocatalytic advanced oxidation processes(AOPs),which devotes a lot to the practical water remediation application.

Self-powered electrochemical system by combining Fenton reaction and active chlorine geheration for organic contaminant treatment

Environmental deterioration,especially water pollution,is widely dispersed and could affect the quality of people's life at large.Though the sewage treatment plants are constructed to meet the demands of cities,distributed treatment units are still in request for the supplementary of centralized purification beyond the range of plants.Electrochemical degradation can reduce organic pollution to some degree,but it has to be powered.Triboelectric nanogenerator(TENG)is a newly-invented technology for low-frequency mechanical energy harvesting.Here,by integrating a rotary TENG(R-TENG)as electric power source with an electrochemical cell containing a modified graphite felt cathode for hydrogen peroxide(H2O2)along with hydroxyl radical(·OH)generation by Fenton reaction and a platinum sheet anode for active chlorine generation,a self-powered electrochemical system(SPECS)was constructed.Under the driven of mechanical energy or wind flow,such SPECS can efficiently degrade dyes after power management in neutral condition without any O2 aeration.This work not only provides a guideline for optimizing self-powered electrochemical reaction,but also displays a strategy based on the conversion from distributed mechanical energy to chemical energy for environmental remediation.

Reinventing MoS2 Co-catalytic Fenton reaction:Oxygen-incorporation mediating surface superoxide radical generation

To better understand the mechanisms of hydrogen peroxide(H_(2)O_(2))’s decomposition and reactive oxygen species(ROS)’s formation on the catalyst’s surface is always a critical issue for the environmental application of Fenton/Fenton-like reaction.We here report a new approach to activate H_(2)O_(2) in a co-catalytic Fenton system with oxygen incorporated MoS2,namely MoS_(2−x) O_(x) nanosheets.The MoS_(2−x) O_(x) nanosheets assisted co-catalytic Fenton system exhibited superior degradation activity of emerging antibiotic contaminants(e.g.,sulfamethoxazole).Combining density functional theory(DFT)calculation and experimental investigation,we demonstrated that oxygen incorporation could improve the intrinsic conductivity of MoS_(2−x) O_(x) nanosheets and accelerate surface/interfacial charge transfer,which further leads to the efficacious activation of H_(2)O_(2).Moreover,by tuning the oxygen proportion in MoS_(2−x) O_(x) nanosheets,we are able to modulate the generation of ROS and further direct the oriented-conversion of H_(2)O_(2) to surface-bounded superoxide radical(·O_(2−surface)).It sheds light on the generation and transformation of ROS in the engineered system(e.g.,Fenton,Fenton-like reaction)for efficient degradation of persistent pollutants.