Three-dimensional electro-Fenton system with iron-carbon packing as a particle electrode for nitrobenzene wastewater treatment

Traditional Fenton oxidation is an effective method for reducing pollutants that are difficult to degrade.Owing to the large amounts of Fe(II),acids,and alkalis added in the reaction,large amounts of Fenton sludge are produced,increasing treatment costs and restricting the method’s application.In this study,we developed a three-dimensional electro-Fenton system by adding iron-carbon filler and investigated the effects of different electrolytic cell structure arrangements,particle electrode dosages,sponge iron(SI)to granular activated carbon(GAC)dosage ratios,current densities,H_(2)O_(2)dosages,and cathodic aeration on nitrobenzene(NB)wastewater treatment.The optimal system conditions were a particle electrode dosage of 100 g/L,SI:GAC mass ratio of 3:1,current density of 30 mA/cm^(2),H_(2)O_(2)dosage of 50 mmol/L,cathodic aeration of 0.8 L/min,and hydraulic retention time of 120 min.The average NB removal rate and chemical oxygen demand reached 67.38%±1.05%and 70.60%±1.15%,respectively,for which the increase in Fenton sludge was 891.8 mg/L.Different from the traditional Fenton process,additional Fe(II)was not required in the process used herein,reducing iron sludge accumulation and lowering the operating costs of using Fenton sludge as a hazardous waste treatment.In addition,the process applied in this study was able to reduce the chemical amounts used and increase the treatment efficiency.The reductions in sludge treatment costs and secondary pollutants make the proposed process an efficient and sustainable alternative for treating NB wastewater.

Electro-Fenton法的影响因素及研究进展

Electro-Fenton法是一种新型的电催化氧化技术,具有"环境友好"的特点,是一种高级氧化技术(AOPs)。结合国内外Electro-Fenton法的研究近况,阐述Fenton法的作用机理及主要影响因素,主要受pH值、O2流量、温度、电流密度、Fe2+离子浓度、电极间距离、电解质及电极材料等因素影响,结合具体的废水对主要反应参数进行总结,分析作用机理。对Electro-Fenton法的研究发展趋势提出了一些观点。

Removal of citrate and hypophosphite binary components using Fenton,photo-Fenton and electro-Fenton processes

Both citrate and hypophosphite in aqueous solution were degraded by advanced oxidation processes （Fe^2＋/H2O2, UV/Fe^2＋/H2O2, and electrolysis/Fe^2＋/H2O2） in this study. Comparison of these techniques in oxidation efficiency was undertaken. It was found that Fenton process could not completely degrade citrate in the presence of hypophosphite since it caused a series inhibition. Therefore, UV light （photo-Fenton） or electron current （electro-Fenton） was applied to improve the degradation efficiency of the Fenton process. Results showed that both photo-Fenton and electro-Fenton processes could overcome the inhibition of hypophosphite, especially the electro-Fenton.

Personal Review:Progress and prospect in electro-Fenton process for wastewater treatment

As a novel advanced oxidation process (AOP), electro-Fenton process is powerful for degrading most organic compounds including toxic and non-biodegradable ones, and so has attracted great attention. This paper reviews this process in detail including the mechanism, electrolytic bath, electrode materials, aerations and operation parameters. The application of electro-Fenton method in wastewater treatment is evaluated and summarized. Future work in this field is suggested, and three main directions of new electrode exploitation, development of assisted technologies and mechanistic study should be strengthened.

Degradation of acid fuchsine by a modified electro-Fenton system with magnetic stirring as oxygen supplying

The current modified electro-Fenton system was designed to develop a more convenient and efficient undivided system for practical wastewater treatment. The system adopted a cathode portion that employed magnetic stirring instead of common oxygen gas diffusion or gas sparging to supply oxygen gas for the electrolyte solution. Key factors influencing the cathode fabrication and activit） were investigated. The degradation of acid fuchsine with a self-made graphite-polytetrafluorethylene cathode was studied using spectrophotometer. It was found that the cathode generated hydrogen peroxide with high current efficiency and the hydrogen peroxide yield of the cathode did not decay after 10 times reuse. With the Pt anode at a ferrous ion concentration of 0.5 mmol/L, a pH of 3, and using magnetic stirring, dye decolorization could be rapidly accomplished but the destruction of benzene rings and intermediates was fairly difficult. With a Fe anode, dye degradation was more complete.

Kinetic degradation of amoxicillin by using the electro-Fenton process in the presence of a graphite rods from used batteries

This study reports the removal of amoxicillin(AMX)in aqueous media using the electroFenton process in the presence of a graphite cathode recovered from used batteries.The impact of the relevant parameters on the electroFenton process,namely the applied current intensity,the temperature,the initial concentration of AMX and the initial concentration of ferrous ions were investigated.The results showed that the optimal values were:I=600 mA,T=25℃,[AMX]_(0)=0.082 mmol·L^( 1) and[Fe^(2+)]=1 mmol·L^(1),leading to 95%degradation and 74%mineralization.The model parameters of AMX mineralization were determined using nonlinear methods,showing that it follows a pseudosecondorder kinetic.The Energy consumption(EC)calculated under the optimal values was found to be 0.79 kWhg 1,which was of the same order of magnitude of those reported in other findings;while it is noteworthy that the electrodes used in our study are of a lower cost.

N-doped carbon-coated Fe_(3)N composite as heterogeneous electro-Fenton catalyst for efficient degradation of organics

Herein,the application of a N-doped graphitic-carbon-coated iron nitride composite dispersed in a N-doped carbon framework(Fe_(3)N@NG/NC)is investigated as a heterogeneous electro-Fenton(HE-EF)catalyst for the efficient removal of organics.The simultaneous carbonization and ammonia etching of iron-based metal organic framework(Fe-MOF)materials yielded well-dispersed N-doped carbon-coated Fe_(3)N nanoparticles with a diameter of~70 nm.The Fe_(3)N and pyridinic N endowed the composite with high HE-EF activity for decomposing the electrogenerated H_(2)O_(2) to•OH.The Fe_(3)N@NG/NC exhibited outstanding HE-EF performance in removing various organic pollutants with low iron leaching.A removal rate of 97-100%could be obtained for rhodamine B(RhB),dimethyl phthalate,methylene blue,and orange Ⅱ in 120 min at a pH of 5.0.When the solution pH was set to 3.0,5.0,7.0,and 9.0,the removal rate of RhB reached 100%,96%,92%,and 81%,respectively,in 60 min at an optimum voltage of 0.0 V(vs.reversible hydrogen electrode(RHE)).Moreover,the concentration of leached iron was expected to be below 0.03 mg/L in a wide pH range of 3.0-9.0.In addition,the RhB removal efficiency remained as high as 90%after six cycles in the reusability experiments.This work highlights the MOF-derived Fe_(3)N composite as an efficient HE-EF catalyst and the corresponding catalytic mechanism,which facilitates its application in wastewater treatment.

Simultaneous utilization of electro-generated O_(2)and H_(2)for H_(2)O_(2)production:An upgrade of the Pd-catalytic electro-Fenton process for pollutants degradation

The Electro-Fenton(EF)process is one of the promising advanced oxidation processes(AOPs)for environmental remediation.The H_(2)O_(2) yield of EF process largely determines its performance on organic pollutants degradation.Conventional Pd-catalytic EF process generates H_(2)O_(2) via the combination reaction of anodic O_(2) and cathodic H;.However,the relatively expensive catalyst limits its application.Herein,a hybrid Pd/activated carbon(Pd/AC)-stainless steel mesh(SS)cathode(PACSS)was proposed,which enables more efficie nt H_(2)O_(2)generation.It utilizes AC,the support of Pd catalyst,as part of cathode for H_(2)O_(2) generation via 2-electron anodic O_(2) reduction,and SS serve as a current distributor.Moreover,H_(2)O_(2) could be catalytically decomposed upon AC to generate highly reactive·OH,which avoids the use of Fe;.Compared with conventional Pd catalyst,H_(2)O_(2) concentration obtained by PACSS cathode is248.2%higher,the O_(2)utilization efficiency was also increased from 3.2%to 10.8%.Within 50 min,26.3%,72.5%,and 94.0%H_(2)O_(2) was decomposed by Pd,AC,and Pd/AC.Fluorescence detection results implied that Pd/AC is effective upon H_(2)O_(2) activation for·OH generation.Finally,iron-free EF process enabled by PACSS cathode was examined to be effective for reactive blue 19(RB19)degradation.After continuous running for 10 cycles(500 min),the PACSS cathode was still stable for H_(2)O_(2)generation,H_(2)O_(2)activation,and RB19 degradation,showing its potential application for organic pollutants degradation without increase in the running cost.

Efficient H_(2)O_(2)Electrosynthesis and Its Electro-Fenton Application for Refractory Organics Degradation

Hydrogen peroxide(H_(2)O_(2))in situ electrosynthesis by O_(2)reduction reaction is a promising alternative to the conventional Fenton treatment of refractory wastewater.However,O_(2)mass transfer limitation,cathodic catalyst selectivity,and electron transfer in O_(2)reduction remain major engineering obstacles.Here,we have proposed a systematic solution for efficient H_(2)O_(2)generation and its electro-Fenton(EF)application for refractory organic degradation based on the fabrication of a novel ZrO_(2)/CMK-3/PTFE cathode,in which polytetrafluoroethylene(PTFE)acted as a hydrophobic modifier to strengthen the O_(2)mass transfer,ZrO_(2)was adopted as a hydrophilic modifier to enhance the electron transfer of O_(2)reduction,and mesoporous carbon CMK-3 was utilized as a catalyst substrate to provide catalytic active sites.Moreover,feasible mass transfer of O_(2)from the hydrophobic to the hydrophilic layer was designed to increase the contact between O_(2)and the reaction interface.The H_(2)O_(2)yield of the ZrO_(2)/CMK-3/PTFE cathode was significantly improved by approximately 7.56 times compared to that of the co nventional gas diffusion cathode under the same conditions.The H_(2)O_(2)generation rate and Faraday efficiency reached125.98 mg·cm^(-2)·h^(-1)(normalized to 5674.04 mmol·g^(-1)·h^(-1)by catalyst loading)and 78.24%at-1.3 V versus standard hydrogen electrode(current density of-252 mA·cm^(-2)),respectively.The high H_(2)O_(2)yield ensured that sufficient OH was produced for excellent EF performance,resulting in a degradation efficiency of over 96%for refractory organics.This study offers a novel engineering solution for the efficient treatment of refractory wastewater using EF technology based on in situ high-yield H_(2)O_(2)electrosynthesis.

Monolithic Mesh-Type Fe-Pd/γ-Al₂O₃/Al Bifunctional Catalysts for Electro-Fenton Degradation of Rhodamine B

A novel Fe-Pd bifunctional catalyst supported on mesh-type γ-Al2O3/Al was prepared and applied in the degradation of Rhodamine B (RhB). The monolithic mesh-type Fe-Pd/γ-Al2O3/Al bifunctional catalyst could be separated from the solution directly and could synthesize H2O2 in situ. The characterization results showed that Fe could improve the dispersion of Pd0, and the electronic interactions between Pd and Fe could increase the Pd0 contents on the catalyst, which increased the productivity of H2O2. Furthermore, DFT calculations proved that the addition of Fe could inhibit the dissociation of O2 and promote the nondissociative hydrogenation of O2 on the surface of Fe-Pd/γ-Al2O3/Al, which resulted in the increasement of H2O2 selectivity. Finally, the in-situ synthesized H2O2 by Pd was furtherly decomposed in situ by Fe to generateOH radicals to degrade organic pollutants. Therefore, Fe-Pd/ γ-Al2O3/Al catalysts exhibited excellent catalytic activity in the in-situ synthesis of H2O2 and the degradation of RhB due to the synergistic effects between Pd and Fe on the catalyst. It provided a new idea for the design of bifunctional electro-Fenton catalysts. Ten cycles of experiments showed that the catalytic activity of Fe-Pd/γ-Al2O3/Al catalyst could be maintained for a long time.

Removal of 17β-Estradiol by Electro-Fenton Process

The Electrochemical advanced oxidation method “Electro-Fenton” has been applied to remove 17β-estradiol (17β)- estra-1,3,5(10)-triéne-3,17-diol) in aqueous-acetonitrile mixture. This endocrine disrupting is a steroid hormone, releases from humans, animals and residual pharmaceuticals into the environmental water and usually causes suspected undesirable effects in aquatic organisms. The degradation of this organic compound by Electro-Fenton process was showed using a carbon felt cathode and platinum anode. The evolution of the concentration during treatment was followed up by high performance liquid chromatography (HPLC). The influence of operating conditions on the degradation of 17β-estradiol by Electro-Fenton step, such as initial concentration and catalyst concentration, has been investi- gated and discussed. We showed that the degradation reaction obeyed apparent first-order reaction kinetics, with absolute rate constant determined as 5.12 × 109 M–1 s–1 by competitive kinetics method taking Benzoic Acid as reference compound. The results confirm the efficiency of the Electro-Fenton process to degrade organic pollutant in aqueous-acetonitrile mixture.

Electro-Fenton法处理某企业羊栖菜废水的实验研究

针对羊栖菜生产废水含盐量高、COD浓度较高、导电性较好等特点,采用electro-Fenton法对其进行处理。探究了该处理过程中初始pH、电流、电压、m(Fe^(2+))∶m(H_2O_2)等对COD去除率的影响。结果表明,最佳运行条件为:pH=3.0,电流20 A,电压15 V,m(Fe^(2+))∶m(H_2O_2)=1∶2,反应经过60 min,此时,COD的去除率为82%。同时,说明了采用Electro-Fenton法处理羊栖菜废水具有反应效率高、运行效果稳定等优点,并且对海带、淡菜等其他海产品加工类废水处理具有指导、借鉴的价值。

Electro-Fenton体系降解RhB特性研究

随着有机染料在多个领域的大规模应用,染料废水污染已然成为水污染最主要的来源之一,然而其高效处理依旧存在一定困难。近年来,Electro-Fenton技术因其高效、绿色被广泛应用和研究。以罗丹明B(RhB)作为染料废水的典型污染物,利用Electro-Fenton技术对其进行降解特性研究,旨在探究其最佳反应条件。结果表明:阴极材料为碳纤维,阳极材料为Pt,C(RhB)=0.010 mmol·L^(-1),C(Na_(2)SO_(4))=70 mmol·L^(-1),C(Fe^(2+))=0.1 mmol·L^(-1),T=30℃,pH=3,E=10 V,该条件下体系氧化效能最高,能够实现RhB在5 min内完全降解。

纳米Fe^0为铁源的Electro-Fenton对甲基橙废水的脱色

以纳米Fe0为铁源的Electro-Fenton(Fe0/E-Fenton)对甲基橙废水的脱色进行了研究。与Fe2+/E-Fenton体系和商用铁粉为铁源的E-Fenton体系相比较,Fe0/E-Fenton对甲基橙的脱色效果更好。Fe0/E-Fenton对甲基橙脱色过程中,相对稳定的溶液的pH值和充足的Fe2+量有利于E-Fenton试剂对甲基橙脱色反应。同时考察了Fe0/E-Fenton反应中初始pH值和纳米Fe0投加量对甲基橙脱色的影响。研究结果表明,当甲基橙初始浓度为20mg·L-1时,溶液pH值和纳米Fe0的投加量分别为3.0和17mg·L-1,甲基橙溶液在45min内完全脱色。

电芬顿法(Electro-Fenton Process)处理废水

电芬顿法(electro-Fenton)是在Fenton试剂的基础上,在二价铁离子(Fe2+)和过氧化氢(H2O2)作用下,产生强氧化性的羟基自由基(●OH)并由其氧化难降解废水,其中Fe2+和H2O2分别由电化学过程产生。本文概述了电芬顿过程的基本原理,通过介绍国内外电芬顿的发展情况,详细介绍了电芬顿的影响因素,包括pH、阴极电极、催化剂及其他因素等,并展望了其未来的发展方向。

A novel electro-Fenton hybrid system for enhancing the interception of volatile organic compounds in membrane distillation desalination

Membrane distillation(MD)is a promising alternative desalination technology,but the hydrophobic membrane cannot intercept volatile organic compounds(VOCs),resulting in aggravation in the quality of permeate.In term of this,electro-Fenton(EF)was coupled with sweeping gas membrane distillation(SGMD)in a more efficient way to construct an advanced oxidation barrier at the gas-liquid interface,so that the VOCs could be trapped in this layer to guarantee the water quality of the distillate.During the so-called EF-MD process,an interfacial interception barrier containing hydroxyl radical formed on the hydrophobic membrane surface.It contributed to the high phenol rejection of 90.2% with the permeate phenol concentration lower than 1.50 mg/L.Effective interceptions can be achieved in a wide temperature range,even though the permeate flux of phenol was also intensified.The EF-MD system was robust to high salinity and could electrochemically regenerate ferrous ions,which endowed the long-term stability of the system.This novel EF-MD configuration proposed a valuable strategy to intercept VOCs in MD and will broaden the application of MD in hypersaline wastewater treatment.

Three-dimensional heterogeneous electro-Fenton system with reduced graphene oxide based particle electrode for Acyclovir removal

New pollutant pharmaceutical and personal care products(PPCPs),especially antiviral drugs,have received increasing attention not only due to their increase in usage after the outbreak of COVID-19 epidemics but also due to their adverse impacts on water ecological environment.Electro-Fenton technology is an effective method to remove PPCPs from water.Novel particle electrodes(MMT/rGO/Fe_(3)O_(4))were synthesized by depositing Fe3O4 nanoparticles on reduced graphene oxide modified montmorillonite and acted as catalysts to promote oxidation performance in a three-dimensional electro-Fenton(3D-EF)system.The electrodes combined the catalytic property of Fe3O4,hydrophilicity of montmorillonite and electrical conductivity of graphene oxides,and applied for the degradation of Acyclovir(ACV)with high efficiency and ease of operation.At optimal condition,the degradation rate of ACV reached 100%within 120 min,and the applicable pH range could be 3 to 11 in the 3D-EF system.The stability and reusability of MMT/rGO/Fe_(3)O_(4)particle electrodes were also studied,the removal rate of ACV remained at 92%after 10 cycles,which was just slightly lower than that of the first cycle.Potential degradation mechanisms were also proposed by methanol quenching tests and FT-ICR-MS.

Electro-Fenton法处理印染废水应用研究进展

Electro-Fenton法是利用电解的方法产生Fe2+和H2O2,新生的Fe2+和H2O2作用产生·OH。作为一种新兴的废水处理技术,在处理难降解有机废水方面,国内外已开展了广泛的研究,对于处理高浓度难降解有机废水效果良好。阐述了Electro-Fenton法的发展、分类、反应机理及其在印染废水处理中的应用研究现状,并指出Electro-Fenton法存在的主要问题和今后的发展方向。

Combination of the direct electro-Fenton process and bioremediation for the treatment of pyrene-contaminated soil in a slurry reactor

A combined treatment technology （DEF-BIO） using the direct electro-Fenton （DEF） process and bioremediation （BIO） was established in this study. The performance of the DEF-BIO process on the remediation of a pyrene （PYR）-contaminated soil was evaluated in a slurry reactor. The appropriate order of application was to conduct the DEF process followed by BIO, evaluated through analysis of the degradation characteristics of each process individually. In addition, the application time of the DEF process affected the efficiency of the combined process. The optimum time to apply the DEF process was determined through an analysis of the induced changes in PYR intermediates, pH, soil organic matter （SOM） and bacteria. The optimum application time of the DEF process was 6 h. All the induced changes were beneficial for the BIO phase. The removal of PYR was 91.02% for DEF- BIO after 72h, and the efficiency was almost 50% increased, compared with the individual DEF and BIO treatments. Therefore, the combined process of DEF-BIO process may be an efficient and promising method for the remediation.

Recent advances and trends of heterogeneous electro-Fenton process for wastewater treatment-review

Electrochemical advanced oxidation processes (EAOPs) are effective and environmentally friendly for the treatment of refractory organic pollutants.Among EAOPs,heterogeneous electro-Fenton (EF) process with in-situ formation of hydrogen peroxide (H_(2)O_(2)) is an eco-friendly,cost-effective and easy-operable technology to generate hydroxyl radicals (;OH) with high redox potential.The generation of;OH is determined by the synergistic H_(2)O_(2)formation and activation.The surface catalytic mechanisms for H_(2)O_(2)activation in the heterogeneous EF process were discussed.Some required features such as heteroatom doping and oxygen groups for H_(2)O_(2)formation via selective two-electron oxygen reduction reaction (ORR) with carbonaceous electrode are summarized.The solid Fenton catalysts and integrated functional cathodes that widely used in heterogeneous EF for wastewater treatment are grouped into few classes.And the brief discussion on catalytic activity and stability of materials over different experimental conditions are given.In addition,the application of heterogeneous EF process on the remediation of emerging contaminants is provided.The challenges and future prospects of the heterogeneous EF processes about catalytic fall-off and multi-step/complex techniques for water purification are emphasized.