Electrochemical Oxidation System Research Articles

Three-dimensional-electrode Electrochemical Oxidation of Refractory Organic Matter in a Cold High-altitude Area: A Case Study of Dibutyl Phthalate

Qinghai has a high altitude, low average temperature and low oxygen concentration, but it has abundant power resources, so it has a good application prospect to use electrochemical oxidation to degrade refractory organic matter. In this study, a three-dimensional electrode electrochemical oxidation system was constructed with powdered activated carbon as the particle electrode, graphite as the anode and stainless steel as the cathode, and the electrochemical oxidation degradation effect of DBP simulated wastewater at high altitude was studied. When applying the system to the simulated wastewater, the maximum chemical oxygen demand (COD) removal rate reached 61.75% at a plate spacing of 5 cm, electrolyte and particle-electrode dosages of 12 g and 35 g, respectively, and an electrolytic voltage of 20 V. Electrolyte voltage is the most influential factor in the COD removal rate, followed by plate spacing, electrolyte dosage, and particle electrode dosage. The graphite electrode was confirmed to be higher-value than ruthenium–iridium, titanium mesh, and lead dioxide electrodes.

Unraveling degradation mechanism and reaction efficacy of sulfamethoxazole via reactive oxygen species dominated radical process

Herein, the Ti4O7 electrode was combined for the first time with various oxidants to generate reactive oxygen species for the removal of different organic pollutants in an electrochemical oxidation (EO) system. The removal efficiency of organic pollutants, reaction mechanism, and degradation pathway were evaluated by electrochemical tests, reaction kinetics, electron paramagnetic resonance, quantum chemical, and density functional theory calculations. As a result, nearly 100 % removal efficiency of sulfamethoxazole (SMX) was achieved within 12 min with a high kinetic rate constant of 0.259 min−1, and the kinetic rate constant was strongly dependent on the electrostatic potential. The O2 site on the peroxymonosulfate (PMS) molecule dominated the radical generation for the removal of SMX via the radical and non−radical process. This current study offers a novel approach toward the electrochemical activation of PMS in the elimination and degradation of various organic pollutant from wastewater.

Electrocatalytic oxidation of hexafluoropropylene oxide homologues in water using a boron-doped diamond electrode

ABSTRACT Hexafluoropropylene oxide (GenX) is a kind of substitute to PFOA, which has been listed in the Stockholm Convention. In this study, GenX was attempted to be degraded using a boron-doped diamond anode in the electrochemical oxidation system. The effects of operating parameters, including current density (0.5–10 mA/cm2), initial pH (3.0–11.49), initial concentration of GenX (20–150 mg/L), electrode distances (0.5–2 cm), electrolyte types (Na2SO4, NaCl, NaNO3 and NaHCO3) and Na2SO4 electrolyte concentration (40–80 mm), on GenX were studied. GenX can almost completely be degraded under the optimal operating parameters after 180 min of electrolysis. Free radical quenching experiments were carried out to investigate the effects of hydroxyl radicals and sulphate radicals on the degradation of GenX. The degradation intermediates were identified based on the ultra-high performance liquid chromatography equipped with a tandem mass spectrometer, and the degradation mechanisms were also proposed. Finally, the toxicities of GenX and its degradation products were evaluated using the QSAR models. The novelty is that the degradation mechanisms of the high concentration GenX (100 mg/L) were elucidated based on the free radical quenching experiments and the intermediates detected, when the degradation ratio reached 100%.

Pilot-scale electrochemical advanced oxidation (EAOP) system for the treatment of Ni-EDTA-containing wastewater

Electrochemical advanced oxidation processes (EAOP) have shown great potential for the abatement of complexed heavy metals, such as metal-EDTA complexes, in recent studies. While removal of metal-EDTA complexes has been extensively examined in bench-scale reactors, much less attention has been given to the efficacy of this process at larger scale. In this study, we utilize a 72 L pilot-scale continuous flow system comprised of six serpentine flow channels and 90 pairs of flow-through electrodes for the degradation of Ni-EDTA complexes and removal of Ni from solution. The influence of a range of key operating parameters including flow rate, current density and initial Ni-EDTA concentration on rate and extent of Ni-EDTA degradation and Ni removal were examined. Our results showed that at a feed flow rate of 36 L h−1, current density of 5 mA cm−2 and initial Ni-EDTA concentration of 1 mM, the pilot-scale system achieved 74 % total Ni removal, 78 % total EDTA removal and 40 % TOC removal with energy consumption of 13.6 kWh m−3 order−1 and energy efficiency of 7.9 g kWh−1 for total Ni removal. A mechanistically-based kinetic model, which was developed in our previous bench-scale study, provides a satisfactory description of the experimental results obtained in the pilot-scale unit. Long term operation of the pilot-scale unit resulted in corrosion of PbO2 anode along with inorganic scaling as well as organic fouling on the PbO2 surface resulting in an obvious decline in Ni-EDTA degradation. Overall, the results of this study suggest that large scale anodic oxidation of wastewaters containing metal-organic complexes is an effective means of degrading organic ligands thereby enabling removal of the metal at the cathode. However, additional efforts are required to enhance the durability of the anode material and reduce material costs and energy consumption.

Synthesis and characterization of Cu-modified ox-g-C3N4 nanosheets as an electrode for green synthesis of phenyl Benzofuran derivatives via C–H functionalization to C–O and C–C bond formation with an electrochemical oxidation system

Synthesis and characterization of Cu-modified ox-g-C3N4 nanosheets as an electrode for green synthesis of phenyl Benzofuran derivatives via C–H functionalization to C–O and C–C bond formation with an electrochemical oxidation system

A sustainable electrochemical strategy utilizing pulsed alternating current and dual carbon felt electrodes for enhanced degradation of organic pollutants: Oxidation performance and mechanisms

In this work, a novel electrochemical (EC) oxidation system utilizing pulsed alternating current (PAC) and dual carbon felt (CF) electrodes has been established for sustainable degradation of sulfamethoxazole (SMX) with no addition of extra oxidant. The EC/PAC system showed high degradation efficiency and energy efficiency compared to the pulsed direct current (PDC) and direct current (DC) systems. The EC/PAC process was effective across a wide pH range of 3–11 for SMX removal. The results showed that the 1O2 confined to the CF electrode surface was the dominant oxidative specie that was generated from dissolved oxygen in the system. Under PAC conditions, the cathode and anode were rapidly switched on the same CF electrode, increasing the generation of 1O2 for enhanced SMX oxidation. Furthermore, the EC/PAC system demonstrated resistance to interference from various anions of different concentration levels found in natural environment. In contrast to the EC/PDC system, the EC/PAC system emerged as a promising option for more efficient H2O2 production. High-resolution mass spectrometry results revealed the SMX degradation pathways and byproducts, which were then evaluated for toxicity removal. Overall, the EC/PAC system offers a green and sustainable solution to future wastewater treatment, with high degradation rates, energy efficiency, and sustainability.

Effective oxidation decomplexation of Cu-EDTA and Cu2+ electrodeposition from PCB manufacturing wastewater by persulfate-based electrochemical oxidation: Performance and mechanisms.

Complex wastewater matrices such as printed circuit board (PCB) manufacturing wastewater present a major environmental concern. In this work, simultaneous decomplexation of metal complex Cu-EDTA and reduction/electrodeposition of Cu2+ was conducted in a persulfate-based electrochemical oxidation system. Oxidizing/reductive species were simultaneously produced in this system, which realized 99.8% of Cu-EDTA decomplexation, 94.5% of Cu2+ reduction/electrodeposition under the conditions of original solution pH = 3.2, electrode distance = 3cm, [Na2S2O8]0 = 5mM, current density = 12mA/cm2, and reaction time = 180min. The total treatment cost is as low as 0.80 USD/mol Cu-EDTA. Effective mineralization (74.1% total organic carbon removal) of the solution was obtained after 3h of treatment. •OH and SO4•- drove the Cu-EDTA decomplexation, destroying the chelating sites and finally it was effectively mineralized to CO2, H2O and Cu2+. The mechanisms of copper electrodeposition on the stainless steel cathode and persulfate activation by the BDD anode were proposed based on the electrochemical measurements. The electrodes exhibited excellent reusability and low metal (total iron and Ni2+) leaching during 20 cycles of application. This study provide an effective and sustainable method for the application of the electro-persulfate process in treating complex wastewater matrices.

Comparative study of electrochemical oxidation system hybrid with photocatalytic system for the treatment of Al-Najaf petroleum refinery wastewater

Comparative study of electrochemical oxidation system hybrid with photocatalytic system for the treatment of Al-Najaf petroleum refinery wastewater

Simultaneous removal of sulfamethazine and sulfate via electrochemical oxidation and capacitive Deionization: Mechanisms of in-situ activation and strategies of the hybrid system

Electrochemical oxidation (EO) is a well-established method for pollutants removal. However, excessive addition of oxidant during EO may cause secondary pollution. Moreover, the unprocessed ions in the wastewater can cause further contamination. This research introduces a hybrid process that combines EO with capacitive deionization (CDI), in situ catalytically utilizing sulfate (SO42-) and removing sulfamethazine (SMZ). This process realized by layered porous MXene-modified biochar electrodes (BCM) that demonstrate electrocatalytic and adsorption properties. The electrochemical oxidation system, constructed using BCM cathode and boron-doped diamond anode, harnesses in situ generation of oxidants from SO42-, leading to the complete degradation of 30 mg/L sulfamethazine in 30 min through adsorbed radicals and metastable active species at the biphasic interface. Subsequently, the BCM-2 exhibits excellent CDI performance at 1.2 V, achieving a desalination capacity of 15.40–65.97 mg/g in 100–1000 mg/L Na2SO4 solution. By combining EO with CDI, BCM simultaneously removes sulfamethazine and sulfate, resulting in a 60 % reduction in total organic carbon and a 14.4 % decrease in electrical conductivity after one process cycle. Moreover, BCM exhibits favorable cytocompatibility.

Quantitative Measurement Technique for Anodic Corrosion of BDD Advanced Oxidation Electrodes.

Electrochemical advanced oxidation (EAO) systems are of significant interest due to their ability to treat a wide range of organic contaminants in water. Boron doped diamond (BDD) electrodes have found considerable use in EAO. Despite their popularity, no laboratory scale method exists to quantify anodic corrosion of BDD electrodes under EAO conditions; all are qualitative using techniques such as scanning electron microscopy, electrochemistry, and spectroscopy. In this work, we present a new method which can be used to quantify average corrosion rates as a function of solution composition, current density, and BDD material properties over relatively short time periods. The method uses white light interferometry (WLI), in conjunction with BDD electrodes integrated into a 3D-printed flow cell, to measure three-dimensional changes in the surface structure due to corrosion over a 72 h period. It is equally applicable to both thin film and thicker, freestanding BDD. A further advantage of WLI is that it lends itself to large area measurements; data are collected herein for 1 cm diameter disk electrodes. Using WLI, corrosion rates as low as 1 nm h-1 can be measured. This enables unequivocal demonstration that organics in the EAO solution are not a prerequisite for BDD anodic corrosion. However, they do increase the corrosion rates. In particular, we quantify that addition of 1 M acetic acid to 0.5 M potassium sulfate results in the average corrosion rate increasing ∼60 times. In the same solution, microcrystalline thin film BDD is also found to corrode ∼twice as fast compared to freestanding polished BDD, attributed to the presence of increased sp2 carbon content. This methodology also represents an important step forward in the prediction of BDD electrode lifetimes for a wide range of EAO applications.

Three-Dimensional Electrochemical Oxidation System with RuO2-IrO2/Ti as the Anode for Ammonia Wastewater Treatment

In this study, a three-dimensional electrochemical oxidation system was constructed to treat ammonia nitrogen wastewater generated from the tail gas absorption of a methionine producer by using a homemade MAC mixed with a GAC at a mass ratio of 1:2 as the particle electrode, with a RuO2-IrO2/Ti polar plate as the anode and a stainless steel plate as the cathode. The effects of current density, initial pH value of wastewater, plate spacing, NaCl concentration and particle filling amount on CODCr and NH4+-N removal were investigated through single-factor experiments, and the removal pathways of CODCr and NH4+-N under the system were initially explored via cyclic voltammetry curves, scanning electron microscopy and tertiary butanol quenching experiments. The experimental results showed that the average removal rate of CODCr was 91.03% and that of NH4+-N was 98.89% after electrolysis for 5 h under the conditions of a current density of 40 mA/cm2, no pH adjustment, the spacing of the electrode plates of 8 cm, the NaCl dosing concentration of 1 g/L, and the particle filling amount of 400 g/L. Under this experimental condition, the removal of CODCr occurred mainly through the indirect oxidation of active chlorine and ·OH, and the removal of NH4+-N mainly through the indirect oxidation of active chlorine.

Treatment of Monochlorobenzene from Polymers Process through Electrochemical Oxidation.

With the rapid development of the economy and the demands of people's lives, the usage amount of polymer materials is significantly increasing globally. Chlorobenzenes (CBS) are widely used in the industrial, agriculture and chemical industries, particularly as important chemical raw materials during polymers processes. CBS are difficult to remove due to their properties, such as being hydrophobic, volatile and persistent and biotoxic, and they have caused great harm to the ecological environment and human health. Electrochemical oxidation technology for the treatment of refractory pollutants has been widely used due to its high efficiency and easiness of operation. Thus, the electrochemical oxidation system was established for the efficient treatment of monochlorobenzene (MCB) waste gas. The effect of a single factor, such as anode materials, cathode materials, the electrolyte concentration, current density and electrode distance on the removal efficiency (RE) of MCB gas were first studied. The response-surface methodology (RSM) was used to investigate the relationships between different factors' conditions (current density, electrolyte concentration, electrode distance), and a prediction model was established using the Design-Expert 10.0.1 software to optimize the reaction conditions. The results of the one-factor experiments showed that when treating 2.90 g/m3 MCB gas with a 0.40 L/min flow rate, Ti/Ti4O7 as an anode, stainless steel wire mesh as a cathode, 0.15 mol/L NaCl electrolyte, 10.0 mA/cm2 current density and 4.0 cm electrode distance, the average removal efficiency (RE), efficiency capacity (EC) and energy consumption (Esp) were 57.99%, 20.18 g/(m3·h) and 190.2 (kW·h)/kg, respectively. The results of the RSM showed that the effects of the process parameters on the RE of MBC were as follows: current density > electrode distance > electrolyte concentration; the interactions effects on the RE of MBC were in the order of electrolyte concentration and current density > current density and electrode distance > electrolyte concentration and electrode distance; the optimal experimental conditions were as follows: the concentration of electrolyte was 0.149 mol/L, current density was 18.11 mA, electrode distance was 3.804 cm. Under these conditions, the RE achieved 66.43%. The response-surface variance analysis showed that the regression model reached a significant level, and the validation results were in agreement with the predicted results, which proved the feasibility of the model. The model can be applied to treat the CBS waste gas of polymer processes through electrochemical oxidation.

An integrated system combining electrochemical oxidation and filtration processes to remove chlorine from pharmaceutical industry wastewater

This research devised an efficient method to treat wastewater generated from heparin production at a local Taiwanese company. The approach combined electrochemical techniques with filtration processes to manage the wastewater, which exhibited high levels of total dissolved solids (TDS), chemical oxygen demand (COD), organic matter, and chlorine concentration, requiring treatment before disposal or potential reuse. A specialized electrochemical oxidation (EO) system was customized for processing 500 mL of solution at a 2A current, working in tandem with an activated carbon filter chamber. Various experiments were conducted, altering potential and adsorption times, to understand their correlation in eliminating the identified pollutants in pharmaceutical wastewater. Notably, sample 4 (S4), following an electrolysis process at 2A-12 V in 5 h and subsequent adsorption by 10 g of activated carbon for 60 min, exhibited remarkable efficacy Specifically, this treatment regime facilitated the removal of over 90 % (from 14,750 to 1422 mg/L) of chlorine concentration, 91 % (from 1.12 to 0.09 a.u.) of turbidity, and 88 % (from 22,676 to 2786 mg/L) of COD from the effluent stream. These favorable outcomes were attributed to the conversion of chlorine ions into hypochlorous acid, renowned for its potent antibacterial properties in eliminating organic compounds, as well as the robust adsorption capabilities of activated carbon. This study underscores the viability of employing surface adsorption and electrochemical processes in tandem, utilizing low input currents and brief treatment durations, to treat pharmaceutical wastewater effectively.

Use Of Two-Dimensional And Three-Dimensional Reactors In Oxidative Electrochemical Degradation Studies Of Malachite Green

With the developments in treatment technologies, including porous materials in electrochemical systems have recently become the focus of researchers' attention. In electrochemical methods, operating cost is as important as efficiency. It is possible to increase the system performance by increasing the effective electrode surface by incorporating activated carbon, which can be produced from biomass, into electrochemical oxidation systems. This study investigated using activated carbon from walnut shells as a microelectrode in the electrochemical oxidative degradation of malachite green. When potential differences between 2V and 4V are applied to 2DES and 3DES reactors containing MG solution, a higher % MG Removal was obtained in 3DES reactors than in 2DES reactors. When the potential difference is 4V, a value of 0.026 (min-1) k1.3D and 0.0117 (min-1) k1.2D are obtained. In 3DES reactors, the rate constant at 0.003 A/cm2 was achieved as 0.0167 (min-1) k1.3D, while at 0.010 A/cm2, it increased by approximately 5 times, reaching a value of 0.0845 min-1 k1.3D. Similarly, in 3DES reactors, when the current density increased from 0.003 A/cm2 to 0.010 A/cm2, the mass transfer rate increased from 0.011 (cm/s) to 0.05633 (cm/s).

By-product of hydrothermal liquefaction: Characterization of biochar and its application in metal-free electrochemical advanced oxidation process of hydrogen peroxide to provide hydroxyl radicals

Hydrothermal liquefaction stands as a prominent method for the conversion of biomass into renewable energy sources. Alongside its production of high-quality biocrude oil, this process, however, inevitably generates by-products. This research was centered on biochar, a by-product of the hydrothermal liquefaction. The structural and morphological properties were explored in-depth, employing various techniques such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, among others. The analysis revealed that biochar showcased an initial inclination towards graphitization, possessing a rough layered structure. Additionally, the biochar surface contained a significant nitrogen content, predominantly in the forms of pyridinic nitrogen, pyrrolic nitrogen, and graphitic nitrogen. These nitrogen species contributed significantly to the electrocatalytic capabilities. Building upon this finding, a biochar-modified glassy carbon electrode was prepared and utilized as the cathode in a metal-free electrochemical advanced oxidation system, facilitating the production of hydroxyl radicals from H2O2. This work delved deep into the mechanism underlying the electrocatalytic reaction. It elucidated that the reduction of H2O2 to ⋅ OH was a diffusion-controlled, one-electron transfer with proton-independent process. Through comparative assessments between the electrocatalytic performance of biochar-modified and unmodified glassy carbon electrodes, the former substantiated a significant enhancement, specifically regarding the reduction of H2O2 for ⋅ OH generation.

In-situ electrodeposition of Co/Ce-MOF-derived carbon composites as anode for electrochemical degradation of ceftazidime

Antibiotics cannot be completely removed through traditional treatment technologies, leading to their accumulation in the aquatic environment and posing a serious threat to human health. MOF-derived carbon is a promising material for the degradation of antibiotics. Herein, in this study, a novel Co/Ce-MOF electrode was rapidly prepared by one-step electrodeposition at room temperature. Then the Co/Ce-MOF electrode was carbonized to obtain MOF-derived carbon composite electrode (Co/Ce-C350Air). The ceftazidime (CAZ) degradation efficiency achieved 96.59% within 60 min under the optimum conditions ([CAZ] = 5 mg/L, [Na2SO4] = 50 mM, current density = 0.8 mA/cm2, electrode gap = 2 cm and initial pH = 5.6) and the degradation process of CAZ conformed to first-order reaction kinetics. Furthermore, the removal efficiency of CAZ maintained at 94.92% even recycling for 6 times, demonstrating the good electrochemical stability of the Co/Ce-C350Air composite anode. The synergistic effect between Co and Ce metals improved the catalytic performance and stability of the Co/Ce-C350Air electrode. Radical quenching experiments and electron paramagnetic resonance (EPR) spectra results revealed that surface hydroxyl radicals were the main active species in the degradation of CAZ. The main intermediate products were identified by high-performance liquid chromatography-mass spectrometry (HPLC-MS) and the possible degradation pathway was proposed. In addition, toxicity tests with Ecological Structure Activity Relationships (ECOSAR) software results indicated that the toxicity of the intermediate products was lower than that of CAZ. This work provided a safe and effective strategy for the degradation of antibiotics in the electrochemical oxidation system.

Balancing sludge reduction and membrane fouling mitigation by tuning electrical voltages of a side-flow electrochemical oxidation system during MBR processing

In this study, a side-flow electrochemical oxidation (EO) process was innovatively integrated with the A2O-MBR, and it was found that sludge reduction could be significantly enhanced, however, membrane fouling mitigation depended on the applied voltages. For the EMBR-20 V system, the strong EO ability realizes an excellent sludge reduction performance (60.3%). However, the secondary organic substances released by lysed sludge cells in the EO process exacerbate membrane fouling, with a 14-day shortened operation time before reaching the 30 kPa TMP limit. Moderate sludge reduction (17.8%) and membrane fouling mitigation (6.3% with a 3-day extended operational time) were simultaneously achieved in the EMBR-3 V system. Notably, returning the lysed sludge did not influence the organics and nitrogen removal in either system, but caused phosphorus concentration in the effluent to increase, mostly because of the substantial reduction of sludge discharge in the EMBR-20 V system. Meanwhile, key enzyme activity levels (ROS and LDH) under 20 V were significantly higher than those under 3 V and the blank group, whereas ATP showed a downward trend, indicating that sludge microorganisms were effectively destroyed under high voltage. In addition, the electrochemical effect can also affect SMP organic component and microbial community structures, which play an important role in membrane fouling and effluent quality. Interestingly, the analysis showed that SMP, not EPS, was the main cause of membrane fouling in the integrated system. After economic evaluation, the operational cost of the EMBR-3 V system was slightly lower (0.50–0.57 ¥/t of water) than that of the single A2O-MBR system (0.56–0.65 ¥), while the EMBR-20 V system cost was significantly higher (1.61–2.03 ¥).

Understanding the Catalytic Active Sites of Crystalline CoSbxOy for Electrochemical Chlorine Evolution.

The chlorine evolution reaction (CER) is a key reaction in electrochemical oxidation (EO) of water treatment. Conventional anodes based on platinum group metals can be prohibitively expensive, which hinders further application of EO systems. Crystalline cobalt antimonate (CoSbxOy) was recently identified as a promising alternative to conventional anodes due to its high catalytic activity and stability in acidic media. However, its catalytic sites and reaction mechanism have not yet been elucidated. This study sheds light on the catalytically active sites in crystalline CoSbxOy anodes by using scanning electrochemical microscopy to compare the CER catalytic activities of a series of anode samples with different bulk Sb/Co ratios (from 1.43 to 2.80). The results showed that Sb sites served as more active catalytic sites than the Co sites. The varied Sb/Co ratios were also linked with slightly different electronic states of each element, leading to different CER selectivities in 30 mM chloride solutions under 10 mA cm-2 current density. The high activity of Sb sites toward the CER highlighted the significance of the electronic polarization that changed the oxidation states of Co and Sb.

Study on the mechanism of rapid degradation of Rhodamine B with Fe/Cu@antimony tailing nano catalytic particle electrode in a three dimensional electrochemical reactor

A novel particle electrode based on antimony tailings microspheres was successfully constructed by ultrasonic immersion calcination method, and the degradation of RhB was studied in a three-dimensional electrochemical reactor (3DER). It was characterized by XRD, SEM, EDS, XPS, cyclic voltammetry and linear sweep voltammetry. When the pH value is 5.00, the dosage of Fe/Cu@antimony tailing is 1.50 g/L, the initial concentration is 100 mg/L, and the current density is 20 mA/cm2, the degradation efficiency is the best (99.40% for RhB and 98.81% for TOC) within 15 min. The results show that in the three-dimensional electrochemical oxidation system, electrochemical oxidation and electro Fenton oxidation occur at the same time to cause the increase of hydroxyl radicals. According to LC-MS analysis and EPR characterization, it can be found that the main degradation mechanism of RhB is that hydroxyl radicals continuously attack RhB, and realize rapid degradation of RhB through deethylation, deamination, dealkylation, decarboxylation, chromophore splitting, ring opening and mineralization. Fe/Cu@antimony tailing particles are both electrodes for electrochemical oxidation and catalysts for Fenton oxidation. The degradation effect of RhB remained at 94% after 6 cycles, and the leaching rates of Fe and Cu are only 1.20% and 0.79%, indicating that Fe/Cu@AT had significant stability. This work provides a new insight into the establishment of an efficient and stable three-dimensional electrocatalytic particle electrode.

Steel slags for enhanced removal of landfill leachate in a three-dimensional electrochemical oxidation system

In this study, a three-dimensional electrochemical oxidation system, with steel slags as particle electrodes, was applied to deal with landfill leachate. The characteristics of particle electrodes were investigated by scanning electron microscope (SEM), X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD) measurements. It was found that the steel slag exhibited rough and irregular surface and mainly consisted of SiO2 (Quartz), which indicated the enhanced absorbed and electroconducted abilities. Subsequently, comparative degradation tests between two-dimensional (2D) and three-dimensional (3D) electrochemical oxidation systems were carried out and results indicated removal efficiencies of COD. Moreover, NH4+-N from landfill leachate in 3D system was greatly improved compared with that of 2D system. Besides, operating conditions were also optimized to interelectrode distance of 1 cm, current density of 20 mA·cm−2, initial pH value of 4.4 and steel slag concentration of 0.30 g·mL−1, all of which were determined to guarantee excellent landfill leachate removal efficiency. In addition, a possible removal mechanism for this system was proposed. The introduction of steel slag particle electrodes in three-dimensional electrochemical oxidation system implied the concept for “using waste to treat waste”, providing a workable way in pollutant elimination.