Three-dimensional electro-Fenton Research Articles

Fe3O4@Fe2O3 carbon aerogel particle electrodes for three-dimensional electro-Fenton oxidation: A novel mechanism promoted by non-radical pathway

Three-dimensional electro-Fenton (3D-EF) has exhibited strengths over traditional electro-Fenton (EF) process for water decontamination, but recent researches on 3D-EF are focused on the decontamination mechanism driven by the radical pathway which was environmentally sensitive and poor in anti-interference capability. This study explored the non-radical mechanism in the 3D-EF process by preparing a novel Fe3O4@Fe2O3/carbon aerogel-700 (FFCA-700) particle electrode (PE) to construct a 3D-EF system promoted by non-radical pathway. The electrodes induced electric field spontaneously polarized FFCA-700 into PEs which led to higher active surface areas of electrodes and the enhancement of mass transfer. Numerous polarized FFCA-700 served as electron donor for dissolved O2 to obtain electron to form ·O2– while the increase in positive charge of the graphitized carbon, caused by the functional group containing electron-rich oxygen, was conducive for ·O2– to transform to 1O2 thus promoting the non-radical pathway. Tetracycline (TC) was selected as the model pollutant to evaluate and compare the remediation performance of different systems. The results suggested that FFCA-700-3D-EF system performed well for pollutant removal in real wastewater. Overall, this study provided a reference for the design and optimization of CPEs and the guidance for the mechanism studies on remediation of organically contaminated wastewater by 3D-EF process.

Photocatalysis coupled electro-Fenton process for treatment of acrylamide wastewater: an optimised study

ABSTRACT Electro-Fenton is a commonly used approach for pollutant removal from different wastewater that requires high energy consumption. Coupling electro-Fenton with solar energy could potentially overcome high power consumption. Thus, this study combined photocatalysis with three-dimensional electro-Fenton to treat acrylamide (AM) wastewater. The removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH3−N), and total organic carbon (TOC) in photocatalysis-coupled electro-Fenton were studied. The effects of current density, iron powder dosage, plate spacing, and photocatalyst dosage on COD and NH3−N removal were also optimised using response surface methodology (RSM). The photocatalysis coupled three-dimensional electro-Fenton reduced energy consumption compared to single photocatalysis or electro-Fenton technology. The COD and NH3−N removal rates were 82.444% and 92.810%, respectively, at the current density of 16.000 mA/cm2, iron powder dosage of 1.330 g, plate spacing of 16.643 mm, photocatalyst dosage of 0.2 g. This study demonstrated that organic pollutants can be degraded efficiently at a low concentration of catalysts coupled with the electro-Fenton process, offering a low-energy consumption treatment of wastewater.

Treatment of bio-treated coking wastewater in a 3DEF system with Fe-loaded needle coke particle electrodes

As one of the most representative hard-to-biodegrade industrial wastewater, coking wastewater is poor in biodegradability and has a high concentration of organic matter. Consequently, even after treatment using biochemical technology, the discharge standards cannot be reached. We used the self-developed Fe-loaded needle coke electrodes (Fe-NCPEs) as particle electrodes and established a three-dimensional electro-Fenton (3DEF) system for the treatment of bio-treated coking wastewater (BTCW) in this study. The 3DEF system's conditions for treating BTCW were optimized using Response Surface Method (RSM). When the initial pH was 4.69, the applied voltage was 11.1 V, the Fe-NCPE dosage was 11.63 g L−1, and the COD was reduced from 387 to 57.3 mg L−1 and the colour removal rate reached 99 % after 3 h of reaction, meeting local coking wastewater discharge standards. The power consumption is only 15 kWh per ton of BTCW, indicating that this system can treat the BTCW with high efficiency and low energy consumption. UV-Vis, FTIR, and GC-MS analysis illustrated that cyclic aromatic compounds, esters, and ethers can be efficiently degraded to alkanes and olefins by the 3DEF system. The ·OH quenching experiments showed that in the 3DEF system, the ·OH is the main reactive group, which can oxidize the large hard-to-degrade organic compounds in BTCW to small organic compounds, and even to CO2 and H2O. Dynamic experiments showed that the 3DEF system can successfully remove pollutants from BTCW under continuous flow conditions with an HRT of 3 h, allowing it to meet emission standards.

Degradation of 2,4-dinitrotoluene from aqueous solutions by three-dimensional electro-Fenton with magnetic activated carbon particle electrodes (GAC/Fe3O4)

Abstract 2,4-Dinitrotoluene (2,4-DNT) is a broadly applied nitroaromatic compound with multiple applications, and its simple production has resulted in its extensive utilization in producing explosives, dyes, and rubber. This substance is hazardous and induces genetic mutations in humans, fish, and microorganisms. Thus, this research was done to assess the effectiveness of the three-dimensional electro-Fenton (3D/EF) process employing magnetic activated carbon particle electrodes (GAC/Fe3O4) in eliminating 2,4-dinitrotoluene from water-based solutions. In this experimental investigation, Fe3O4 nanoparticles were created using the chemical co-precipitation technique. The G/β-PbO2 anode was fabricated by electrochemically depositing PbO2 layers on graphite sheets. G/β-PbO2 and stainless steel were utilized as the anode and cathode, respectively. The structure, particle size, and properties of the GAC/Fe3O4 nanocomposite were analyzed using FESEM, XRD, and EDX. The morphology of the G/β-PbO2 electrode was also examined using SEM. The Taguchi experimental design method was employed to identify the optimal conditions. The outcomes demonstrated that higher reaction time and current density, as well as lower pH and pollutant concentration, resulted in improved 3D/EF efficiency. Accordingly, the optimum values of parmeters were identified to be a concentration of 2,4-DNT = 50 mg/L, pH = 3, electrolysis time = 100 min, and current density = 8 mA/cm2. With these parameters, the degradation efficiency of 2,4-DNT through the examined system was 98.42 %, alongside removal efficiencies of 84.69 % for COD and 79.67 % for TOC. Additionally, the results indicated an increase in the average oxidation state (AOS) (from 1.27 to 1.95) and carbon oxidation state (COS) (from 1.27 to 2.75) in the 3D/EF process, along with a decrease in the COD/TOC ratio (from 1.81 to 1.36), indicating the effectiveness of the 3D/EF system in enhancing the biodegradability of 2,4-DNT. Overall, the combined 3D/EF process with a G/β-PbO2 anode has relatively high efficiency in degrading solutions containing DNT and can be considered a viable treatment option for wastewater containing substances such as 2,4-DNT.

Efficient carbamazepine removal from wastewater using a continuous three-dimensional electro-Fenton system at natural pH

This research presents an innovative approach for removing carbamazepine (CBZ), a persistent pharmaceutical contaminant, using a three-dimensional electro-Fenton (TDEF) system. The preliminary phase involved validating the configuration of the TDEF reactor. First, commercial electrodes, metal-mixed oxide as the anode, and stainless steel as the cathode were selected. After that, a third particulate electrode was introduced, working with two options: vineyard biochar and a lab-made conglomerate of perovskite and carbon black. Additionally, two collector systems were evaluated for easy recovery and reuse of this three-dimensional particulate electrode: a thermoplastic tube and a silicone bag. Among the tested configurations, the perovskite conglomerate retained within a silicone bag proved the most effective, achieving a 91 % CBZ removal efficiency at a natural pH (6.5) during a 5-hour batch operation. Considering excellent results, the system's efficacy was confirmed working on fortified tertiary wastewater (FTW) in continuous mode, emphasizing the adaptability to real-world conditions. Moreover, the reusability of microparticles was confirmed for three consecutive cycles, as well as through the characterization study using FTIR, without important modifications in the material after use. Results confirmed the technology's potential for removing CBZ operating with real conditions. Thus, the proposed process represents an alternative treatment to remove CBZ efficiently in a wide range of concentrations from real wastewater in a continuous treatment with a reasonable energy cost (ca. 27 kW/h·gCZP). This novel system represents a cost-effective, straightforward experimental setup suitable for future scaling and industrial applications.

Enhancing the treatment efficiency of three-dimensional electro-Fenton system for organic wastewater: An analysis from the comprehensive perspective of H2O2 generation

For optimizing H2O2 generation in three-dimensional electro-Fenton (3D-EF) to enhance efficacy in treating organic wastewater, a comprehensive analysis from various perspectives of H2O2 generation was provided. By quantifying the generation of H2O2 within the reaction system and comparing it with the changing trends in organic wastewater treatment efficiency, a close correlation between H2O2 generation and organic wastewater treatment was revealed. A reliable and accurate kinetic model for H2O2 generation was formulated by building upon the reactions of H2O2 with electrodes and coexisting substances. The mathematical formulation of the kinetic model pinpointed pivotal factors influencing H2O2 generation, including current density, dissolved oxygen concentration, and the Fe catalytic activity substance. The experimental data and fitted results under various conditions indicated that the model could reasonably and accurately describe the relationship between pivotal factors and the quantity of generated H2O2. Crucial strategies were proposed to enhance H2O2 generation in the 3D-EF system by drawing from the impact rules of pivotal factors on H2O2 generation. These strategies primarily focused on improving electrode performance, optimizing reactor conditions, and refining particle electrode preparation processes.

Three-dimensional electro-Fenton system with steel-slag based particle electrode for the treatment of refinery spent caustic

Refinery spent caustic (RSC) is a highly contaminated wastewater originated from the petroleum refining industry with complicated chemistry and high toxicity. In this work, a novel three-dimensional electro-Fenton (3DEF) system assisted by electromagnetic induction was developed to treat an actual RSC with a chemical oxygen demand (COD) concentration of 27000–33000 mg/L. Industrial waste steel slag was used as both the particle electrode and the Fenton’s catalyst. Under optimal conditions, COD removal reached 93.6% within 90 min. Electromagnetic induction significantly enhanced COD degradation by promoting the corrosion of steel slag, inhibiting the electrode passivation, and enhancing the thermal activation of hydrogen peroxide. The reusability of steel slag was also enhanced by electromagnetic induction. Radical quenching tests demonstrate that hydroxyl radicals (•OH) played a main role in the pollutant degradation. The system is of good economic and environmental benefits with a total treatment cost of about 1.015 $/m3, achieving the objective of “treating waste with waste”.

Three-dimensional electrochemical Fenton degradation of CIP by doping Ce and Cu in Jacaranda shell base as particle electrodes

Currently, ciprofloxacin (CIP) in water environments has attracted wide attention. In order to degrade CIP by electrocatalysis, it is very important to develop catalysts with high catalytic activity as particle electrodes. In this study, Jacaranda shell was made into biochar (BC) by calcination, Ce and Cu modified BC (Ce-Cu/BC) was prepared by a simple impregnation and calcination method as a particle electrode in a three-dimensional electro-Fenton (3D/EF) system to degrade CIP. Characterization of the Ce-Cu/BC particle electrodes was conducted using SEM, XRD, and XPS, revealing the porous structure of the calcined jacaranda shell base, confirming successful loading of Ce and Cu. Optimal operating conditions for CIP removal were determined to be 4 g/100 mL particle electrodes dosage, initial pH of 5, 8 V voltage, and 2 mM Fe2+ concentration, resulting in a maximum CIP removal rate of 84.97% with an energy consumption of 1.32 W•h. Stability tests demonstrated the robustness of Ce-Cu/BC, while comparative tests and radical extinction experiments highlighted the high electrocatalytic activity of the 3D/EF system, primarily attributed to the indirect oxidation of •OH, an active substance generated within the system LC-MS and UV full-band scanning analyses were employed to propose potential CIP degradation pathways.

Preparation of particle electrodes for landfill leachate treatment by doping Cu2+-modified needle coke with Fe-based oxides extracted from iron tailings

Landfill leachate is a typically difficult-to-degrade organic wastewater that, if not treated properly will cause serious harm to human health and the ecological environment. Three-dimensional electro-Fenton (3DEF) technology has received widespread attention because of its high mass transfer efficiency and current utilisation, and no secondary pollution. In this study, the Fe/Cu-loaded needle coke particle electrode (Fe/Cu-NCPE) was prepared, using which a 3DEF system was constructed with DSA as the anode and Ni/ACF as the cathode to treat mature landfill leachate. The optimal preparation conditions of the Fe/Cu-NCPE were obtained as Cu2+-modified needle coke: Fe-based oxides: binder = 32:8:15, particle size of 5 ± 0.5 mm, and Cu2+ loading of 3 %. The spectral analysis shows that the Fe/Cu-NCPE prepared in this study is a kind of particle electrode with superior performance and good stability. The optimum conditions for treating landfill leachate at an applied voltage of 9 V, an initial pH of 2, and a Fe/Cu-NCPE dosage of 25 g/L resulted in the removal of COD, colour, TN, and NH3-N of 94.2 %, 99 %, 90.3 %, and 93.8 %, respectively. In the 3DEF system for landfill leachate treatment, H2O2 is generated at the cathode and polarized Fe/Cu-NCPE surface, which is activated by loaded Fe2+ and Cu+ in a Fenton(-like) reaction to produce •OH; Meanwhile active chlorine is generated by anodic electrocatalytic oxidation of Cl-. They attack humic acid and other organics in the wastewater as well as nitrogenous reductive substances to degrade them.

Accelerated Cr (VI) removal by a three-dimensional electro-Fenton system using green iron nanoparticles.

Green-synthesized iron nanoparticles (GAP-FeNP) were used as particle electrodes in a three-dimensional electro-Fenton (3DEF) process to accelerate the removal of hexavalent chromium [Cr (VI)]. Removal was evaluated by varying the pH (3.0, 6.0, and 9.0) and initial Cr (VI) concentrations (10, 30, and 50 mg/L) at 5 and 25 min. These results demonstrated that GAP-FeNP/3DEF treatment achieved more than 94% Cr (VI) removal under all tested conditions. Furthermore, it was observed that Cr (VI) removal exceeded 98% under pH9.0 in all experimental parameters tested. The results of the response surface methodology (RSM) determined two optimal conditions: the first, characterized by a pH of 3.0, Cr (VI) concentration at 50 mg/L, and 25min, yielded a Cr (VI) removal of 99.7%. The second optimal condition emerged at pH9.0, with Cr (VI) concentrations of 10mg/L and 5min, achieving a Cr (VI) removal of 99.5%. This study highlights the potential of the GAP-FeNP to synergistically accelerate Cr (VI) removal by the 3DEF process, allowing faster elimination and expansion of the alkaline (pH9.0) applicability. PRACTITIONER POINTS: The required time for >99% of Cr (VI) removal by the GAP-FeNP/3DEF process was shortened from 25 to 5min. EF process with GAP-FeNP reduces the time necessary for Cr (VI) removal, which is 67% faster than conventional methods. EF process using GAP-FeNP removed >94% of Cr (VI) after 25 min for all initial Cr (VI) concentrations and pH treatments. Cr (VI) removal by the GAP-FeNP/3DEF process was >98% at a pH of 9.0, widening the solution pH applicability.

3D electro-Fenton augmented with iron-biochar particle electrodes derived from waste iron bottle caps and sugarcane bagasse for the remediation of sodium dodecyl sulphate

The present work demonstrates a novel strategy of synthesizing iron-biochar (Fe@BCSB) composite made with the waste iron bottle cap and sugar cane bagasse for implementation in the three-dimensional electro-Fenton (3DEF) process. The catalytic ability of the Fe@BCSB composite was explored to remediate the sodium dodecyl sulphate (SDS) surfactant from wastewater at neutral pH. At the optimum operating condition of Fe@BCSB dose of 1.0 g L−1, current density of 4.66 mA cm−2, and Na2SO4 dose of 50 mM, nearly 92.7 ± 3.1% of 20 mg L−1 of SDS abatement was attained during 120 min of electrolysis time. Moreover, the Fe@BCSB showed significant recyclability up to six cycles. Besides, other organics were successfully treated with more than 85% abatement efficiency in the proposed Fe@BCSB-supported 3DEF process. The total operating cost obtained during SDS treatment was around 0.31 US$ m−3 of wastewater. The phytotoxicity test revealed the positive impact of the 3DEF−treated effluent on the germination of the Vigna radiata. The electron paramagnetic resonance conveyed •OH as the prevailing reactive species for the oxidation of SDS in the 3DEF process. Further, about 81.3 ± 3.8% of SDS and 53.7 ± 4.1% of mineralization efficacy were acquired from the real institutional sewage.

Establishment of a reagent-free three-dimensional electro-Fenton system for high H2O2 production and efficient degradation of Roxarsone

Urgent attention is needed to address the potential threat of organic arsenic agents causing water pollution. A novel approach was developed for the removal of Roxarsone (ROX) employing a reagent-free three-dimensional electro-Fenton (TD-EF) system. This system utilized gas diffusion electrode (GDE) as the cathode, which consisted of ZIF-67 carbonized in a N2 atmosphere (ZIF-67-NC) and carbon black (CB) in a specific ratio (ZIF-67-NC/CB-GDE), graphite as the anode and granular activated carbon (GAC) loaded with FeSO4·7H2O (FeSO4-GAC) as the particle electrode. The characterization and electrochemical measurements indicated that ZIF-67-NC contained abundant active sites and had excellent catalytic properties for the oxygen reduction reaction (ORR). It was observed that under specific conditions of aeration, 100 mM Na2SO4 electrolyte solution, electrode distance of 4 cm and current of 200 mA, 170 mM of H2O2 could be produced in 60 min, and the removal rate of ROX could reach 98.1 % within 100 min. Reactive oxygen species (ROSs) trapping experiments confirmed that O2− and OH were the major ROSs for ROX degradation. The possible degradation pathways were further investigated, and the results were consistent with Density Functional Theory (DFT) calculations. The evolution of inorganic arsenic during the reaction was explored using liquid chromatography-atomic fluorescence coupled with atomic fluorescence (LC-AFS). These studies revealed that the toxicity of the degraded intermediates was mitigated by the degradation reaction. Furthermore, the degradation rate of ROX in the system was at least 90 % over a relatively wide pH range (3.0–8.9), and the removal efficiency of the system remained almost constant after five cycles. This work provides new ideas for the construction of a reagent-free TD-EF system offering high H2O2 yield and excellent durability for efficient degradation of organic pollutants.

Enhanced removal of Ni-EDTA by three-dimensional electro-Fenton process using Fe-N-doped biochar as catalytic particle electrodes

Heavy metal complexes pose a challenge in terms of their resistance to removal due to their stable and intricate structure. In this study, we explored the utilization of Fe and N co-doped biochar derived from rice husk (Fe-N-RHBC) as catalytic particle electrodes in a three-dimensional electro-Fenton (3D-EF) system for the decomplexation and removal of a model pollutant, Ni-EDTA. The characterization analysis and comparison of catalytic activities confirmed the beneficial effects of Fe and N co-doping on various aspects, such as the types of active sites, interfacial electron transfer properties, and H2O2 decomposition capacity. Compared to other investigated oxidation systems, the 3D-EF process demonstrated rapid removal of Ni-EDTA within the initial minute, with a maximum H2O2 utilization of 99.1% after 30 min. The prepared catalytic particle electrodes exhibited high stability and catalytic capacity even after three consecutive cycles. Throughout the reaction, several processes, including anode oxidation, particle electrode polarization, catalysis, and adsorption of Fe-N-RHBC, as well as cathodic electro-deposition, synergistically contributed to the treatment of Ni-EDTA. The surface-bound O2− radicals and 1O2 generated by the Fe-N-RHBC catalytic particle electrode played a crucial role in the decomplexation and removal of Ni-EDTA. Building upon these findings, we further proposed potential mechanisms for the removal of Ni-EDTA in the 3D-EF system using the Fe-N-RHBC catalytic particle electrode.

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/Fe3O4) 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/Fe3O4 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.

Enhancement of excess sludge dewatering by three-dimensional electro-Fenton process based on sludge biochar.

Deep dewatering of waste activated sludge (WAS) is still a challenge due to high content of bound water and non-Newton fluid properties of sludge flocs. Electro-Fenton (EF) can enhance sludge dewaterability, however, low pH needed in homogeneous EF and fine flocs after EF conditioning influenced deep dewatering of sludge and the subsequent resource recovery disposal. In this study, a three dimension electro-Fenton (3D-EF) using Fe modified sludge biochar (Fe@SBC) as particle electrode, heterogeneous Fenton catalyst and skeleton builder for deep dewatering of sludge under neutral pH was proposed. Fe@SBC obtained at 800°C exhibited high capacity of H2O2 electrogeneration and activation due to high conductivity and content of 2e-ORR selectivity functional groups. With promoted generation of H2O2 and hydroxyl radical (•OH), 3D-EF with Fe@SBC showed higher decomposition of bound extracellular polymeric substances (EPS) and disintegration of cells in sludge flocs, resulting in releasing bound and intracellular water into free water. Compared with EF, 3D-EF with Fe@SBC800 had higher ability in breaking macromolecules of protein and polysaccharide, as well as removing -COOH and -NH2 groups in EPS, which could facilitate release of bound water trapped in EPS and self-coagulation of fine flocs. During subsequent filtering process, Fe@SBC could enhance sludge filterability as skeleton builder. A synergetic effect of strong oxidation and physical conditioning were proposed in 3D-EF sludge dewaterability with Fe@SBC, and the improved oxidation by Fe@SBC was supposed to play the major role.

Performance and working mechanism of a coal fly ash-based particle electrode in the catalytic oxidation of ofloxacin in a three-dimensional electro-Fenton reactor

Coal fly ash (CFA), corn straw, and pharmaceutical wastewater are typical solid and liquid wastes. In this study, activated carbon (CSAC) was first produced by carbonising corn straw, and then a particle electrode with Fenton-like catalytic performance (Fe/CFA-CSAC) was prepared and used in a three-dimensional electro-Fenton process (Fe/CFA-CSAC EF process) to treat ofloxacin-simulated wastewater (OSW). Fe/CFA-CSAC was first characterised using SEM+EDX, XRF, BET test, and XRD, and then the critical treatment parameters of OSW were optimised (T = 30 °C, aeration rate = 3 L/min, current density = 12 mA/cm2). The catalytic oxidation process was critical in the degradation of ofloxacin, while the adsorption process played an auxiliary role. The water quality had a significant improvement, 63.6 % of COD and 51.4 % of TOC were eliminated, BOD5/COD was increased from 0.12 to 0.44, and the toxic inhibition rate was reduced by 40.8 %. Fe/CFA-CSAC EF process can effectively work in a wide pH range (2.0–9.0) and can be used at least 25 cycles. The material costs required for the preparation of Fe/CFA-CSAC was $219.9/ton and the treatment cost of OSW was $1.71/ton. Finally, the working mechanism of Fe/CFA-CSAC was proposed.

A pH self-regulated three-dimensional electro-Fenton system with a bifunctional Fe-Cu-C particle electrode: High degradation performance, wide working pH and good anti-scaling ability

Three-dimensional electro-Fenton system (3DEF) shows great prospect for wastewater treatment. However, the development of an efficient particle electrode with wide working pH and good anti-scaling ability still remains a challenge. In this study, a novel iron-copper-carbon black (Fe-Cu-C) composite was fabricated through a one-step process of pyrolyzing the metal-resin precursors and worked as the particle electrode in the three-dimensional electro-Fenton reactor. In this system with electrodes polarization, the anode-to-cathode flow mode created a locally acidic zone in the packed bed with Fe-Cu-C particle, which facilitated the H2O2 generation from 2-electron reduction of O2 and decomposition into •OH via heterogeneous Fenton reaction. Consequently, it was found that average p-Nitrophenol (p-NP) removal efficiency of 88% and average COD removal efficiency of over 76% were achieved even after 6 h continuous treatment in the continuous-flow 3DEF system packed with Fe-Cu-C particles at a current density of 20 mA cm−2 and flow rate of 1.33 mL min−1. Noticeably, the flow-through 3DEF had the appreciable anti-scaling ability to resist the deactivation of particle electrodes induced by hardness ions and showed little sensitivity to solution pH in the range of 4.0–10.0 with specific energy consumption of approximately 0.089 kW h g−1 COD. Generally, this material could be used as a low-cost particle electrode in combination with flow-through 3DEF for practical wastewater treatment.

Process Optimization of Three-Dimensional Electro-Fenton System for Treatment of Wastewater Produced in Acrylamide Manufacturing Industry

Process Optimization of Three-Dimensional Electro-Fenton System for Treatment of Wastewater Produced in Acrylamide Manufacturing Industry

Efficient degradation of semi-coking wastewater in three-dimensional electro-Fenton by CuFe2O4 heterocatalyst.

Semi-coking wastewater contains a rich source of toxic and refractory compounds. Three-dimensional electro-Fenton (3D/EF) process used CuFe2O4 as heterocatalyst and activated carbon (AC) as particle electrode was constructed for degrading semi-coking wastewater greenly and efficiently. CuFe2O4 nanoparticles were prepared by coprecipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy disperse spectroscopy (EDS). Factors like dosage of CuFe2O4, applied voltage, dosage of AC and pH, which effect COD removal rate of semi-coking waste water were studied. The results showed that COD removal rate reached to 80.9% by 3D/EF process at the optimum condition: 4V, 0.3g of CuFe2O4, 1g of AC and pH = 3. Trapping experiment suggesting that hydroxyl radical (•OH) is the main active radical. The surface composition and chemical states of the fresh and used CuFe2O4 were analyzed by XPS indicating that Fe, Cu, and O species are involved into the 3D/EF process. Additionally, anode oxidation and the adsorption and catalysis of AC are also contributed to the bleaching of semi-coking waste water. The possible mechanisms of 3D/EF for degrading semi-coking waste water by CuFe2O4 heterocatalyst were proposed.

Decomplexation of Ni-EDTA by Three-Dimensional Electro-Fenton

Ni-ethylenediaminetetraacetic acid (Ni-EDTA) poses serious threats to the ecological environment and human health, due to its acute toxicity and low biodegradability. The decomplexation efficiency of Ni-EDTA through the conventional Fenton process has been constrained to pH; thus, other appropriate approaches are required to destroy the stable chelate structure at a neutral pH. In this study, the effect of operating parameters such as the pH, Fe2+ concentration, particle electrode dosage, current density, and coexisting ions was studied. The results revealed that the 3D-EF system owned advantages for the removal of Ni-EDTA in the broadening of the pH application window. The Ni-EDTA removal efficiency in the 3D-EF system reached 84.89% after 120 min at a pH of 7. In addition, the presence of coexisting ions slightly affected the decomplexation efficiency of Ni-EDTA.