Three-dimensional Electrode System Research Articles

A novel NiFe-LDH/AC three-dimensional particle electrode system and its application for degradation of N-nitrosamines: Condition optimization and degradation mechanism

A green and sustainable three-dimensional particle electrodes system with nickel-iron layered double hydroxide mixing activated carbon particles (NiFe-LDH/AC) as particle electrodes is used in this work. Its employment in degradation of N-Nitrosodiethylamine (NDEA), A type of nitrosamines disinfection byproducts (NAs) widely present in water bodies, exhibiting significant degradation efficiency at close to neutral pH. Response surface methodology (RSM) is used to analyze the interaction effects and predict optimal conditions of four operating parameters (influent water flow, electrolyte concentration, current density and initial concentration) on the NDEA degradation efficiency. Calculated coefficients of determination (R2) are higher than 0.997 for all responses according to analysis of variance. At optimum conditions, a maximum degradation efficiency of 71.88% is achieved for NDEA. The results of electron paramagnetic resonance (EPR) and free radical quenching experiments indicate that the degradation of NDEA in the 3D AER system is dominated by •OH. Furthermore, based on the recognition of main reaction intermediates by GC-MS and density functional theory (DFT), possible degradation pathway is proposed and toxicological evaluation of degradation products is made. Our research provides a promising alternative method for the efficient and environmentally friendly removal of NAs from water.

Electrochemical oxidation of ammonia in a granular activated carbon/peroxymonosulfate/chlorine three-dimensional electrode system

The electrochemical conversion of ammonia into harmless nitrogen gas (N2) remains a significant challenge in wastewater treatment. This study explores the utilization of granular activated carbon (GAC) as three-dimensional particle electrodes within a peroxymonosulfate (PMS)/Cl−-PbO2/Ti electrochemical system to enhance ammonia oxidation and N2 transfer efficiency. In the observed experimental parameters designated as optimal, the system demonstrated a complete amelioration of ammonia within 45 min. The porous surface of GAC electrodes facilitates increased contact area, promoting better interaction with target compounds. This interaction leads to improved mass transfer efficiency, reduced chlorine overpotential, and enhanced current response. Quenching experiments reveal the substantial involvement of hydroxyl radicals (•OH), sulfate radicals (SO4•−), and chloride radicals (Cl•) in the oxidation process of NH4+-N, with Cl• generation through the oxidative process involving Cl− and SO4•− under electrical stimulation. After 90 min, a significant portion of NH4+-N is transformed into N2, achieving a conversion efficiency of 71.5 %. Additionally, the system demonstrates efficient removal of ammonia from practical aqueous environments. Three-dimensional fluorescence spectroscopic analysis confirms the system's effectiveness not only in removing ammonia but also in reducing organic substances resembling fulvic acid. These findings underscore the three-dimensional electrochemical GAC/PMS/Cl− system as a promising and efficient approach for ammonia removal in wastewater treatment applications.

Iron-nitrogen co-doped biochar (FeN@BC) as particle electrode for three-dimensional (3D) electro-peroxydisulfate process for tetracycline degradation

In this work, a three-dimensional electrode material (FeN@BC) was prepared by doping iron-nitrogen sites into biochar for activating peroxydisulfate (E-FeN@BC-PS). The scanning electron microscope, x-ray diffractometer, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy results of FeN@BC proved that Fe–N sites were successful doped into BC. Electrochemical analysis indicated that FeN@BC could enhance the electron transfer in the electrochemical process. A significant synergistic effect (SI = 12.46) was observed in the E-FeN@BC-PS system. Tetracycline (TC) was almost removed completely within 30 min in optimal operating parameters. Radical scavenging experiments showed that ·OH, SO4●−, O2●−, and 1O2 all contributed to TC degradation. The cyclic experiment and characterizations before and after the recycle showed that the FeN@BC in the three-dimensional electrode system exhibited excellent stability and reusability, and electricity had an obvious protective effect on the FeN@BC materials. This study revealed the synergistic catalytic mechanism of metal and heteroatomic hybrid materials as three-dimensional electrodes in persulfate activation, promising the development of sustainable and efficient water treatment technology.

Intensive Treatment of Organic Wastewater by Three-Dimensional Electrode System within Mn-Loaded Steel Slag as Catalytic Particle Electrodes.

Developing a green, low-carbon, and circular economic system is the key to achieving carbon neutrality. This study investigated the organics removal efficiency in a three-dimensional electrode reactor (3DER) constructed from repurposed industrial solid waste, i.e., Mn-loaded steel slag, as the catalytic particle electrodes (CPE). The CPE, a micron-grade material consisting primarily of transition metals, including Fe and Mn, exhibited excellent electric conductivity, catalytic ability, and recyclability. High rhodamine B (RhB) removal efficiency in the 3DER was observed through a physical modelling experiment. The optimal operating condition was determined through a single-factor experiment in which 5.0 g·L-1 CPE and 3 mM peroxymonosulfate (PMS) were added to a 200 mL solution of 10 mM RhB under a current intensity of 0.5 A and a 1.5 to 2.0 cm distance between the 2D electrodes. When the initial pH value of the simulated solution was 3 to 9, the RhB removal rate exceeded 96% after 20 min reaction. In addition, the main reactive oxidation species in the 3DER were determined. The results illustrated that HO• and SO4•- both existed, but that the contribution of SO4•- to RhB removal was much lower than that of HO• in the 3DER. In summary, this research provides information on the potential of the 3DER for removing refractory organics from water.

Synergistic removal of sulphur-containing malodourous gases via peroxydisulfate activation in three-dimensional electrode system

A novel technology for peroxydisulfate (PDS) activation in a three-dimensional electrode system (3DES) was employed to purify sulphur-containing malodourous gases; the technical parameters of the process were optimised and the pathway of sulphur-containing malodourous substances was investigated. In 3DES, reactive substances such as SO4• ˉ, 1O2, and •OH were markedly higher, the SO4• ˉ radicals played a significant role in the context of sulphur-containing malodourous gases, and the conversion of CH3SH and CS2 was more complete. The CH3SH in the inlet gas was completely removed within 180 min, the CS2 removal was approximately 100% before 60 min, and it then tended to decline gradually. As H2S and NH3 coexisted in the inlet gas, there was no significant effect on odour removal, and the discarded absorption solution could be used to prepare nitrogen fertiliser as the efficiency of odour removal decreased. The particle electrode in 3DES not only promoted the transfer of insoluble gases into the absorption solution but also enhanced PDS activation. Consequently, the catalytic oxidation performance was greatly improved. A conversion pathway was proposed to explain the transformation of sulphur-containing components such as CH3SH and CS2. This study provides new insights for the removal of malodourous pollutants.

Enhanced nitrogen and phosphorus removal by a novel ecological floating bed integrated with three-dimensional biofilm electrode system

The ecological floating bed (EFB) has been used extensively for the purification of eutrophication water. However, the traditional EFB (T-EFB) often exhibits a decline in nitrogen and phosphorus removal because of the limited adsorption capacity of fillers and inadequate electron donors. In the present study, a series of electrolysis-ecological floating beds (EC-EFBs) were constructed to investigate the decontamination performance of conventional pollutants. EC-EFB outperformed T-EFB in terms of nitrogen and phosphorus removal. Its removal efficiency of total nitrogen and total phosphorus was 20.51–32.95% and 45.06–96.20%, which were higher than that in T-EFB.. Moreover, the plants in EC-EFB demonstrated higher metabolic activity than those in T-EFB. Under the electrolysis condition of 0.51 mA/cm2 for 24 h, the malondialdehyde content and superoxide dismutase activity in EC-EFB were 6.08 nmol/g and 22.61 U/g, which were significantly lower compared to T-EFB (38.65 nmol/g and 26.13 U/g). And the soluble protein content of plant leaves increased from 3.31 mg/g to 5.72 mg/g in EC-EFB. Microbial analysis revealed that electrolysis could significantly change the microbial community and facilitate the proliferation of nitrogen-functional microbes, such as Thermomonas, Hydrogenophaga, Deinococcus, and Zoogloea. It is important to highlight that the hydrogen evolution reaction at the cathode area facilitated phosphorus removal in EC-EFB, thereby inhibiting phosphorus leaching. This study provides a promising and innovative technology for the purification of eutrophic water.

A three-dimensional in-situ self-electrolysis system based on Ni3(HITP)2/graphene-based composite aerogel particle electrodes for efficient deep removal of phenol from coking wastewater

Herein, a Ni3(HITP)2/graphene-based composite aerogel (Ni3(HITP)2/GA) particle electrode is developed for the oxidation removal of phenol with three-dimensional electrode technology. The as-constructed three-dimensional electrode system possesses high in-situ self-electrolysis capacity and achieves highly efficient degradation of phenol, completely removed within 15 min with a decomposition rate constant of 0.3283 min−1. Ni3(HITP)2 in Ni3(HITP)2/GA and the tetradentate Ni–N2O2 coordination bond generated at the composite interface produce H2O2 highly selectively via the 2e- ORR pathway. The graphene layer converts H2O2 into •OH by using the 1e- of Ni3(HITP)2 excitation and the microelectrode action of the particle electrode. Furthermore, the simultaneous generation of •OH and O2•- in the system greatly reduces the dependence on acidic environment and broadens the scope of utilization. The present work provides a new strategy for the efficient construction of particle electrodes in 3D electrode systems, which allows their potential application in the purification of coking wastewater.

Removal performance and mechanism for a three-dimensional electrode system treating biochemical effluent of a wastewater treatment plant.

With the increasingly strict discharge requirements, it is urgent for wastewater treatment plants (WWTPs) to find an efficient and feasible technology for advanced treatment. A three-dimensional (3D) electrode system was used to treat the real biochemical effluent of a WWTP collecting industrial and domestic wastewater in the present study. The 3D electrode system had the best performance at a current density of 2 mA/cm2 and an electrode distance of 3 cm. The kinetic analysis showed that the organic pollutant degradation conformed to pseudo-first-order kinetics. The COD removal of the 3D electrode system was more than twice that of the two-dimensional (2D) electrode system, and the energy consumption was 46.56% less than that of the 2D electrode system. By measuring the adsorption capacity and the electrocatalytic ability of the system to produce strong oxidizing species, it was demonstrated that granular activated carbon (GAC) had the synergy of adsorption and electrochemical oxidation, and ·OH playing the dominant role in oxidizing pollutants. At the same time, the organic contaminants adsorbed on GAC could be degraded. Finally, the adsorption-electrochemical oxidation mechanism was proposed. The above results highlighted that the 3D electrode system was a promising alternative method in the application of advanced treatment for WWTPs.

Optimization of the effect of microelectrodes on Ni2+ removal in three-dimensional electrode system.

This study investigated Ni+2 removal performance in 3DER reactors where electrocoagulation mechanisms and microelectrodes are used together. EDTA modification was carried out on the granule-activated carbon surface to increase the efficiency and affinity of microelectrodes against Ni+2 molecules. The grafting was examined using BET, FT-IR, SEM, EDS, and the elemental mapping methods. With the surface analyses made in this study, it was revealed that EDTA modification on granulated activated carbon was successfully performed. Also, 8.48%wt by mass of EDTA grafting on granular activated carbon was possible. EDTA functionalization did not affect the surface pore structures of CAC much. Under 10V potential, 97.82% Ni removal efficiency was obtained with 2D in 35min, while 96.69% removal in 10min and 100% removal in 15min were obtained in the 3D reactor. The Ni+2 removal mechanism in 3DER reactors has been determined to conform to the pseudo-second-order kinetic model. The k2 value obtained for 10V (1.36 10-2) is 27 times the k2 value obtained for 5V for 3DER reactors. In addition, using central composite design (CCD), operational parameters such as time, concentration, and potential difference affecting Ni+2 removal in 3DER reactors have been optimized. The most influential parameter is the applied voltage, followed by time and concentration. It has been determined that 3DER reactors using EDTA-modified microelectrodes are highly efficient and suitable for Ni+2 removal.

Performance analysis of a half-batch multi-cell three-dimensional electrode reactor for drilling wastewater: COD removal, energy consumption and hydrodynamic characteristic

Although a three-dimensional electrode system (3DES) has made remarkable achievements in improving the property of electrodes and investigating pollutant degradation mechanism, the design of an electrochemical reactor for application in drilling wastewater has not been reported yet. In this study, a novel half-batch multi-cell 3DES reactor was constructed by us to degrade organic compounds from drilling wastewater. The separate effect of electrolysis time, current density, the configuration of granular activated carbon (GAC) electrodes, aeration rate and volumetric recirculation flow on chemical oxygen demand (COD) removal and energy consumption of the half-batch reactor were analyzed, and further optimization via response surface methodology (RSM). Results showed that the optimal operation conditions for the reactor included electrolysis time of 100 min, a current density of 9.2 mA/cm2, GAC electrode vertical configuration, an aeration rate of 2.67 L/min and a volumetric recirculation flow of 100 mL/min. Under these conditions, the maximum percentage COD removal was found to be 97.39% with an energy consumption of 77.89 kWh(kg COD)-1. The residence time distribution (RTD) method was carried out in continuous flow pattern to investigate the hydrodynamic characteristics of the reactor. Results showed that flow rate was the most dominant factor for the flow pattern of the reactor, followed by the aeration rate and current density. The low dispersion number and the percentage of dead volume are 0.214 and 3.87% when the flow rate of 100 mL/min, respectively, which indicates that there is an intermediate flow pattern existing in between plug-flow ideal and complete mixing flow, furthermore, it is close to the plug-flow ideal.

Removal of ammonia nitrogen from wastewater by three-dimensional electrode system based on solid waste containing iron

In order to solve the problem of ammonia nitrogen pollution, three-dimensional electrode electrochemical oxidation technology is utilized to transform ammonia nitrogen. The influence of influent pH, power supply and electrolyte concentration on ammonia nitrogen removal by three-dimensional electrode method and its mechanism were discussed by single factor variable analysis. The particle electrode by emission scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The results show that the removal efficiency of ammonia nitrogen by three-dimensional electrode is higher than that by two-dimensional electrode. When the aqueous solution is neutral, the direct and indirect oxidation reactions of ammonia nitrogen can reach the best state, and the removal efficiency is the highest. Within a certain range, the electrolytic efficiency will increase with the increase of electrolytic voltage and electrolyte concentration. The reduction of electrode spacing in a certain range can enhance the direct oxidation of ammonia nitrogen and improve the electrolysis efficiency of ammonia nitrogen. Under the conditions of pH 7, power supply voltage 14 V, electrolyte concentration 0.1 mol/L, electrode spacing 1 cm, electrolytic time 50 min, ammonia nitrogen can be completely removed from the three-dimensional electrode.

Application of sulfide-modified nanoscale zerovalent iron electrodes for electrokinetic remediation of chromium-contaminated soil in a three-dimensional electrode system

A modified electrokinetic remediation (EKR) system was designed to remediate Cr-contaminated soil using sulfidated nano-scale zerovalent iron (S-nZVI) as the third electrode. This study systematically compared the technological parameters and remediation efficiencies of three-dimensional (3D) electrokinetic systems using different materials as the third electrodes. The comparative experiment showed that the 3D EKR could effectively increase current efficiency, balance voltage distribution, alleviate excessive acidification or alkalization of soils and effectively improve the removal efficiency of Cr. Compared with other 3D electrodes, the S-nZVI electrode led to the higher currents and the more uniform voltage distribution; additionally, the leaching toxicities were reduced by 50.0–66.7%, and the removal efficiencies of total Cr (Cr(tot)) and hexavalent Cr (Cr(VI)) were increased by at least 15.4% and 22.6%, respectively. Cr(VI) was removed mainly resulting from the electrokinetic migration. Meanwhile, a small amount of Cr(Ⅵ) was converted to FeCr2O4 and Cr3+OOH after reacting with S-nZVI in the middle region of the 3D EKR system. Due to the active layer of iron sulfides, S-nZVI was more stable and its electrokinetic efficiency was higher than other 3D electrodes, resulting in higher overall removal efficiencies. 3D EKR with S-nZVI can effectively decrease the toxicological effect of Cr contaminated soil at an experimental scale. The experimental findings from this study may provide a reference for guiding the development of more efficient methods for Cr-contaminated soil treatment.

Optimization for simultaneous removal of NH3-N and COD from coking wastewater via a three-dimensional electrode system with coal-based electrode materials by RSM method

Abstract The present work demonstrated preparation of coal-based electrode materials (CEM)-derived low-rank coal for simultaneous removal of ammonia nitrogen (NH3-N) and chemical oxygen demand (COD) from coking wastewater by a three-dimensional electrode system (3DES). The influence of important parameters in 3DES such as processing time, applied voltage, electrode plate spacing, mass of commercially activated carbon (CAC), and initial pH were investigated. Based on the central composite design, the response surface method (RSM) was employed in order to optimize the variable parameters in removal process of pollutants. From the analysis of RSM, the optimum conditions for 3DES were 4.5 h of processing time, 5.5 V of applied voltage, 17 mm electrode plate spacing, 4.5 g CAC, and pH of 3 with higher simultaneous removal rate of COD (74.20%) and NH3-N (51.48%). Besides, the content of N element (4.9%) and N containing groups were traced by SEM-EDS and FTIR analysis in order to verify the removal effect. The experiment results showed the capability of CEM for electrode system removal of pollutants from coking wastewater and obtained considerable simultaneous removal rate of NH3-N and COD.

The research on the control of chlorinated by-products by the combined process of three-dimensional electrode system and ultraviolet-photocatalytic oxidation.

Advanced oxidation technology is considered to be the most potential wastewater treatment technology. As one of the advanced oxidation technologies, the three-dimensional electrochemical system (3DES) is often used to treat industrial wastewater that is difficult to degrade. Sulphonated phenolic resin (SMP) was treated as a characteristic pollutant in sulfonated drilling wastewater. The separate effect of current, the dosage of particle electrodes, chloride ion concentration and initial pH on chlorinated by-products were analyzed by response surface methodology (RSM). Results showed that current is the most dominant factor, followed by the dosage of particle electrodes. The ultraviolet-electrolysis (UVEL) system was implemented by adding ultraviolet light under the optimal electrolysis (EL) system. The chemical oxygen demand (CODcr) and total organic carbon (TOC) removal rates of the UVEL system were respectively increased by 19% and 29.39% compared with the EL system, the concentration of chlorinated by-products was also reduced by 534.4 mg/L when the UV irradiance was 5.24 mW/cm2. These results indicated that the UVEL system degrades SMP more thoroughly. The enhanced reaction mechanism of the UVEL system and the possible degradation pathway for SMP were proposed by controlling free radical quenching experiments and the product of EL and UVEL processes. The results showed that the high degradation efficiency of the UVEL system could be attributed to the synergistic degradation mechanism present in the UVEL system, where the photolysis of active chlorine species (ACl) promotes the increase of hydroxyl radical (·OH).

Highly efficient removal of amoxicillin from water by three-dimensional electrode system within granular activated carbon as particle electrode

Amoxicillin (AMX) is a widely used broad-spectrum antibiotic. In this study, a three-dimensional electrode system (3DES) was constructed with granular activated carbon (GAC) packed between the anode and cathode electrodes to degrade AMX. Under optimal conditions of 3DES (current density of 5 mA/cm2, 17 mM NaCl as the electrolyte, an initial pH of 5.56, and a GAC-quartz sand volume ratio of 9:1), the removal efficiency of AMX reached 98.98 % after 2 h of treatment. It was also shown that the total organic carbon (TOC) removal efficiency (R) and reaction rate constant (k) of 3DES were 47.6 % and 0.22 h−1, respectively, much higher than the sum of the two-dimensional electrode system (2DES) and adsorption process (30.7 % and 0.12 h−1). Thus, there existed the synergy between electrolysis and adsorption in 3DES, which enhanced the TOC removal efficiency and removal rate by up to 35.5 % and 46.8 %, respectively. Electrochemical characterization was explored using an electrochemical workstation. It demonstrated that GAC played an important role in reducing the mass transfer resistance, and the mass transfer rate of 3DES was 2.24 times that of the 2DES. It was also deduced that AMX adsorbed on the surface of GAC directly participated in the electrochemical oxidation to achieve the in-situ regeneration of activated carbon. The results of Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) of GAC verified it again. In summary, 3DES has good electrochemical performance, and it is an efficient, cost-effective, and environmentally friendly system for AMX degradation.

Cleaner production on electrochemical removal of sulphonamide from wastewater using three-dimensional electrode system: characterisation and kinetics

ABSTRACT In the examination of increasing interest in emerging pollutants, advanced technologies for emerging pollutants have been focused in the environmental science field. This study focuses on the sulphonamide removal from aqueous phase using designed three-phase three-dimensional electrode reactor. The parameters such as pH, particle electrode concentration, initial concentration of sulphonamide and the applied voltage have been studied using batch experiments. Sulphonamide was removed in 60 min at 12 V, pH 3 and 15 g of particle electrode in an electrochemical cell. From fact-finding, it was concluded that the efficiency of the electrochemical reactor increases with a decrease in pollutant concentration with optimum voltage (12 V). SEM-EDS and FTIR have been used for the characterisation of Sulphuric acid-activated Strychnos potatorum particle electrodes (SASP). The removal of sulphonamide using this reactor followed the pseudo-second-order (R2 > 0.96) and Langmuir–Hinshelwood kinetics (R2 = 0.9504). This newly designed three-dimensional reactor is an effective system for the complete removal of toxic pollutants from wastewater and this can be an alternative to the existing system.

Treatment of Methyl Blue Wastewater by Steel Slag Particle Three-Dimensional Electrode System

The particle electrode was prepared by using industrial waste slag as raw material, and the surface morphology of the particle electrode was characterized by scanning electron microscopy. The comparison experiments showed that under the same experimental conditions, the efficiency of removing the methyl blue from the three-dimensional electrode of the steel slag particles was 23.48% higher than that of the two-dimensional electrode, and the energy consumption was reduced by 36.2%. The results showed that the primary and secondary factors affecting the methyl blue wastewater of steel slag particles are electrolyte concentration, voltage, initial waste concentration and particle volume. Under the optimal combination of pH 3, voltage 12 V, initial methyl blue concentration of 15 mg/L and electrolyte concentration of 0.3 mol/L, the removal rate of methyl blue reached 91.41%.

Electrochemical treatment of organic pollutants in landfill leachate using a three-dimensional electrode system

The use of three-dimensional electrode is a new electrochemical oxidation technology for landfill leachate treatment. In this study, a particle electrode was developed using Fe/C granules, which were suspended between the cathode and the anode to create a three-dimensional electrode. The three-dimensional electrode activated sodium persulfate to treat landfill leachate. Fe/C granules were prepared by incorporating iron filings and hydrothermally carbonized biochar into alginate beads. The optimal parameters of the three-dimensional electrode for chemical oxygen demand (COD) removal from landfill leachate were determined based on a series of single factor experiments as an operating voltage of 5V, a sodium persulfate concentration of 28mM, and 1g of Fe/C granules. Treatment with the three-dimensional electrode at optimized conditions achieved 72.9% removal of COD and 99.9% removal of ammonia nitrogen, resulting in landfill leachate being clear and transparent. The changes in total organic carbon, nitrite, and nitrate concentrations indicated that most organic pollution and ammonia nitrogen were converted into CO2 and N2. This study provides an alternative technology for the treatment of refractory organic pollutants.

Treatment of cyanide wastewater dynamic cycle test by three-dimensional electrode system and the reaction process analysis

ABSTRACT Dynamic three-dimensional electrode system treatment of cyanide wastewater used coal-based electrodes as cathode and anode, activated carbon as particle electrodes, the effects of applied voltage, reaction time and flow rate on ion removal rate were studied. SEM-EDS and XPS were used to study the morphology of coal-based electrode and the composition and existing state of the load substances, and the reaction mechanism were analysed and discussed. The results show that the removal rates of CNT, Cu, Zn, CN−, SCN− in cyanide wastewater were 97.03%, 95.79%, 99.82%, 99.42% and 94.19%, respectively, when the applied voltage of 4 V, the electrode distance of 10 mm, the flow rate of 30 ml/min, the reaction time of 2.5 h and the dosage of activated carbon particles of 2 g. The applied voltage is the key factor affecting ion removal. When the voltage was 2 V, the ion removal is mainly due to the synergistic effect of chemisorption and electrosorption. The CN−, SCN−, and metal cyanide complex anions in wastewater migrate to the anode of coal-based anode and particle electrode rapidly under the combined action of electric field and magnetic stirring. On the surface of porous coal-based electrode, the removal of CN−, SCN− was mainly attributed to the oxidation of oxygen evolution from the anode reaction, while the removal of Cu, Zn and other metal ions was mainly by the electrodeposition process on the cathode surface.

Investigation of a novel pyrolusite particle electrode effects in the chlorine-containing wastewater.

Research on three-dimensional electrode system mainly focuses on the material of plate electrode and catalytic activity, and minimal attention is provided to particle electrode. Pyrolusite was prepared as a novel particle electrode with high active chlorine (ACl) yield. The particle electrode was characterised by scanning electrode microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and electrochemical properties. Results show that the intended pyrolusite particle electrode was prepared successfully. These pyrolusite particle electrodes were applied to degrade sulphonated phenolic resin in chlorine-containing wastewater and displayed an excellent catalytic activity. A total of 68.76 mg/L ACl was produced, and the CODCr removal rate was 49.55%. These results indicated that pyrolusite particle electrode is much more effective than the reference material, that is, granular activated carbon. Furthermore, the product of electrolytic process was characterised by gas chromatography-mass spectrometry (GC-MS) and ultraviolet visible spectrometry (UV-vis). The enhanced mechanism was proposed that the high degradation efficiency could be ascribed to the increase of ACl.