PbO2 Anode Research Articles

Electrochemically enhanced hydrophobic modification of La-doped PbO2 anode by peroxymonosulfate for ceftazidime removal

Electrochemically enhanced hydrophobic modification of La-doped PbO2 anode by peroxymonosulfate for ceftazidime removal

PbO2/rGO Electrode as a Superior and Efficient Anode in Electrocatalytic Degradation of Safranine-O

The electrocatalytic degradation method with PbO2/rGO electrode (anode) was chosen to treat Safranine-O waste because it was cheap and environmentally friendly. This research aimed to study the electrocatalytic efficiency of PbO2/rGO working electrode in Safranine-O removal. In this research, rGO and PbO2/rGO electrodes were synthesized and applied to Safranine-O removal through electrochemical degradation. The characterization results of the morphology of rGO are in the form of a layered structure and have the atomic composition of C (82.87%) and O (17.13%). The characterization results of PbO2/rGO are uniform particles with gaps/pores that appear relatively large. The rGO particles in the form of sheets (layers) seem to be distributed on the surface of PbO2. PbO2/rGO electrode has the atomic composition of C (87.24%), O (9.03), and Pb (3.73). The application of PbO2/rGO anode to the electrochemical degradation of Safranine-O showed good performance. It was able to perform dye removal (DE%), as well as a decrease in BOD and COD values up to >95% within 10 minutes at a concentration of 20 ppm. Application on real waste also showed the ability of dye removal, COD, and BOD reduction up to >95%. Coating or modifying the PbO2 anode with rGO can reduce the dissolution of Pb2+ ions in the solution during the electrochemical degradation. This study concluded that the PbO2/rGO electrode has improved the efficiency in Safranine-O degradation. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Electrochemical degradation of m-nitrophenol using an innovative zeolite modified PbO2 anode: Electrode characterization, influence factors and degradation mechanism

In this study, a zeolite-doped PbO2 (Zeo-PbO2) anode was fabricated via electrodeposition technology for electrochemical oxidation of m-nitrophenol (m-NP). The results of characterization revealed that doping zeolite efficiently promoted the oxygen evolution potential and active sites of PbO2 anode, thereby higher performance to generate •OH radical and degrade the m-NP. The •OH radical was confirmed to be the primary contributor to the electrochemical oxidation of m-NP by scavenging tests. Thus, the effect mechanism of current density, supporting electrolyte, and initial pH on the removal of m-NP in the electrochemical oxidation process was explored by the generation of •OH radicals at different conditions. Based on the vulnerable sites of m-NP to the attack of •OH radical supposed by the theoretical calculation and degradation intermediates identified by GC-MS and IC, the degradation pathways of m-NP in the electrochemical oxidation process were speculated. Besides, the good recyclability and stability of Zeo-PbO2 anode were exhibited in consecutive m-NP degradation, •OH generation experiments, and accelerated life tests.

CNTs/Ce co-doped PbO2 anode for electro-oxidation of triclosan: Fabrication, kinetics, and degradation mechanism based on DFT calculations

In this study, an efficient Ti/SnO2-Sb2O3/CNT-Ce-PbO2 electrode was fabricated for triclosan electro-oxidation by co-doping the transition metal Ce and carbon nanotubes (CNTs) into the PbO2 active layer. Characterization results show that the co-doped Ce and CNTs present a synergistic effect on covering the obvious cracks on the Ti/SnO2-Sb2O3 surface, decreasing the PbO2 crystal size, increasing the electrode oxygen evolution potential from 1.60 to 2.17 V vs SCE, and reducing the charge transfer resistance by 66 %. Consequently, Ti/SnO2-Sb2O3/CNT-Ce-PbO2 was the most effective and energy-efficient electrode for hydroxyl radical (•OH) generation and triclosan electro-oxidation in this study. Compared with other two electrodes (Ti/SnO2-Sb2O3 and Ti/SnO2-Sb2O3/Ce-PbO2), triclosan removal by Ti/SnO2-Sb2O3/CNT-Ce-PbO2 was accelerated by 1.8–2.6 times, with the energy demand for abating 90 % triclosan (EEO) decreased by 49 % – 67 %. Furthermore, triclosan degradation pathways were proposed based on density functional theory (DFT) calculation and transformation product (TP) identification, with •OH addition at C14 and C11 sites being the most favorable pathway. In addition, the estimated acute and chronic toxicities of TPs were generally decreased than their mother compound. Therefore, the results of this study suggest the feasibility and effectiveness of the Ti/SnO2-Sb2O3/CNT-Ce-PbO2 electrode for triclosan electro-oxidation.

PbO2 /graphite and graphene/carbon fiber as an electrochemical cell for oxidation of organic contaminants in refinery wastewater by electrofenton process; electrodes preparation, characterization and performance

The electro-Fenton oxidation process was used to treat organic pollutants in industrial wastewater as it is one of the most efficient advanced oxidation processes. The novel cell in this process consists of a prepared PbO2 electrode by electrodeposition on graphite substrate and carbon fiber modified with graphene as a cathode. X-ray diffraction, fluorescence, analysis system, atomic force microscopy, and scan electron microscopy were used to characterize the prepared anode and cathode. XRD patterns clearly show the characteristic reflection of the mixture of  - and β phases of PbO2 on graphite and carbon fiber, and AFM results for cathode and anode present that PbO2 on graphite substrate and graphene on carbon fiber surface are on a nanoscale. Contact angle measurement was determined for the carbon fiber cathode before and after modification. The anodic polarization curve showed a higher anodic current when utilizing the PbO2 anode than the graphite anode. Phenol in simulated wastewater was removed by electro-Fenton oxidation at 8 mA/cm2 current density, 0.4 mM of ferrous ion concentration at 35 °C up to 6 h of electrolysis. Chemical oxygen demand for the treated solution was removed by 94.02 % using the cell consisting of modified anode and cathode compared with 81.23% using modified anode and unmodified cathode and 79.87 % when using unmodified anode and modified cathode.

Challenges in the determination of reactive oxygen species evolving during membrane water electrolysis for in situ ozone production

The treatment of ultrapure water with electrochemically produced O3 is a common means for disinfection yet leads to the formation of a variety of reactive oxygen species (ROS). The present study draws a comprehensive comparison between three commonly used photometric and fluorometric assays for ROS analysis and quantifies the individual signal responses for dissolved O3, ·OH and H2O2, respectively, to account for cross-sensitivities. By calibrating all combinations of assays and analytes, we developed a quantification procedure to reliably determine the actual ROS composition in ultrapure water environments for different operation conditions of a membrane water electrolyzer with PbO2 anodes down to concentrations of 0.97 μg L−1. While the ·OH formation rate can be described linearly over the observed current density range, substantial O3 evolution is only found for current densities of 0.75 A cm−2 and above (up to 3.7 μmol h−1 for J = 1.25 A cm−2). The formation of H2O2 is only observed when an organic carbon source is introduced into the solution. We further quantify the interference of H2O2 with the reading of the oxidation-reduction potential as a common water parameter and elaborate on its validity to monitor the peroxone process when both H2O2 and O3 are present simultaneously.

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.

Mechanism Studies in Electrochemical Depolymerization Processes of Alkali and Organosolv Lignin

AbstractTo better understand the process and mechanism of lignin structural changes and relative product formation during PbO2 anode electrolysis, a Ti/Sb−SnO2/PbO2 composite electrode has been prepared and utilized for the alkaline electrolytic oxidation of both alkali lignin (AL) and bagasse organosolv lignin (OL). By combining electrochemical measurements, in‐situ FTIR, 2D‐HSQC NMR, and product distribution analysis, we not only investigate the impact of influence factors on the process of lignin depolymerization, but also reveal the depolymerization mechanism from the whole process of lignin structural changes in details. Under certain electrolysis conditions, the highest vanillin yield, 10.1 mg g−1, has been obtained through the electrolysis of alkali lignin, whereas the highest syringaldehyde yield of 4.0 mg g−1 has been achieved during the electrolysis of organic solvent lignin. In particular, AL mainly performs depolymerization through the selective cleavage C−C bonds to produce a series of G unit monomer products of vanillin, acetovanillone, and vanillic acid. By contrast, the depolymerization of OL shows significant selectivity in H units. Particularly, the production of the major H unit monomer product of 4‐vinylphenol has been confirmed by IR spectroelectrochemical studies from the oxidation and decarboxylation of p‐coumaric acid unit.

Performance enhancement of electrochemical degradation of H-acid wastewater via novel membrane electrode assembly electrolyser

A membrane electrode assembly (MEA) based electrolyser is designed and fabricated for H-acid wastewater treatment and harmful chemical degradation. The electrochemical O3 and H2O2 generation performance has been greatly enhanced owing to the nano PbO2 catalyst on the anode and the PTFE/C catalyst on the cathode. Since the anode oxidation (AO) combined with oxygen reduction reaction (ORR) enhances ·OH radical generation, the in situ AO-ORR coupling system shows better mineralization efficiency and lower electrochemical energy consumption for organic degradation. Additionally, the nano PbO2 anode exhibited excellent stability and maintained high degradation efficiencies after 15 times of successive reuse of the in situ AO-ORR coupling system. Based on 16 identified intermediates categorized as primary, secondary, and downstream intermediates, a possible degradation pathway of the H-acid electrochemical oxidation was proposed and the toxicity was drastically reduced after the degradation.

Efficient electrochemical degradation of ceftazidime by Ti3+ self-doping TiO2 nanotube-based Sb–SnO2 nanoflowers as an intermediate layer on a modified PbO2 electrode

Ceftazidime (CAZ) is an emerging organic pollutant with a long-lasting presence in the environment. Although some PbO2 materials exhibit degradation capabilities, inefficient electron transport in the substrate layer and the problem of electrode stability still limit their use. Here, an interfacial design in which TiO2 nanotube arrays generate Ti3+ self-doping oxide substrate layers and highly active 3D Sb–SnO2 nanoflowers-like interlayers was used to prepare PbO2 anodes for efficient degradation of CAZ. Interestingly, after implementing Ti3+ self-doping in the PbO2 anode base layer and introducing 3D nanoflowers-like structures, the capacity for •OH generation increased significantly. The modified electrode exhibited 5-fold greater •OH generation capacity compared to the unmodified electrode, and a 2.7-fold longer accelerated electrode lifetime. The results indicate that interfacial engineering of the base and intermediate layers of the electrodes can improve the electron transfer efficiency, promote the formation of •OH, and extend the anode lifetime of the activated CAZ system.

Boosting hydroxyl radical generation for highly efficient electrooxidation of sulfamethazine via facile doping strategy

The one-electron water oxidation reaction (WOR) to generates hydroxyl radicals (•OH) plays a pivotal role in electrochemical advanced oxidation processes (EAOPs). In this study, we present a novel and facile strategy involving Ho-doping to regulate the electronic configuration of the conventionally nonactive PbO2 electrode. Experimental findings demonstrate that PbO2 doped with 2.4% Ho achieves the highest degradation performance of sulfamethazine (SMZ) (∼100%; kobs = 0.093 min−1) and highest •OH generation efficiency with a relatively concentration of •OH = 1.9 × 107. The doped electrodes exhibit a notable enhancement compare to the undoped electrode, which elevating SMZ degradation efficiency and •OH generation by factors of 1.45 and 3.8, respectively. Electrochemical characterization and degradation results elucidate that the modulation of electron transfer rate and oxygen evolution potential are crucial factors governing the performance of the Ho-doped PbO2 anode. Specifically, maintaining a suitably high oxygen evolution potential (OEP) enables the thermodynamically feasible production of •OH, while a relatively fast electron transfer rate ensures the generation of H2O+ (the oxidation precursor of •OH) with kinetic feasibility. Furthermore, a degradation pathway for SMZ is proposed based on the identification of transformation mechanism using density functional calculation (DFT) and the detection of intermediates via LC-MS/MS. This study provides an universal strategy for simultaneously enhancing the OEP and optimizing the electron transfer rate of an EAOP anode through the modulation of anodic electronic configuration, thereby advancing the field of efficient water treatment applications.

A new Co-doped PbO2 anode for copper electrowinning: Electrochemical and morphological characterization

Anodic electrodeposition was used to create a high catalytic activity Co-doped PbO2 composite coating on Ti substrate, in order to reduce the overpotential and raising the electrocatalytic activity for oxygen evolution during the copper electrowinning process. The temperature, composition, and current density of the electrolyte were investigated in order to produce a composite anode with the best electrocatalytic behavior, stability, and efficiency in the electrowinning process. Scanning electron microscopy (SEM) was utilized to investigate the morphology of the coating, and electrowinning, cyclic voltammetry (CV), and the accelerated life time test (ALT) were employed to evaluate the electrodes' electrochemical behavior. The ideal conditions in this investigation involved 65 g.L−1 cobalt nitrate with a 5 mA.cm−2 current density at 65 °C for the electrodeposition of Co-doped PbO2 coating. Furthermore, the potential for oxygen evolution of the PbO2-CoOx anode was found to be approximately 180 and 220 mV lower than that of the PbO2 and Pb-Ca-Sn anodes, respectively, based on the results of the electrochemical test. The ALT test results showed that the PbO2-CoOx anode had a significantly lower initial cell voltage than the Pb-Ca-Sn and PbO2 anodes; however, this value increased after 165 h due to the anode's mechanical breakdown. The results showed that Cu electrowinning efficiency for Pb-Ca-Sn, PbO2, and PbO2-CoOx was 91.9 %, 98.4 %, and 100 % respectively.

Electrochemical treatment of wastewaters containing metal-organic complexes: A one-step approach for efficient metal complex decomposition and selective metal recovery

Metal-organic complexes, especially those of ethylenediaminetetraacetic acid (EDTA) with metals such as copper (Cu) and nickel (Ni) (denoted here as Cu-EDTA and Ni-EDTA), are common contaminants in wastewaters from chemical and plating industries. In this study, a multi-electrode (ME) system using a two-chamber reactor and two pairs of electrodes is proposed for simultaneous electrochemical oxidation of a wastewater containing both Cu-EDTA and Ni-EDTA complexes as well as separation and selective recovery of Cu and Ni onto two different cathodes via electrodeposition. Our results demonstrate that the ME system successfully achieved 90% EDTA removal, 99% solid Cu recovery at the Cu recovery cathode and 56% Ni recovery (33.3% on the Ni recovery cathode and 22.6% in the solution) after a four-hour operation. The system further achieved 85.5% Ni recovery after consecutive five cycles of operation for 20 h. While Cu removal was mainly driven by the direct reduction of EDTA-complexed Cu(II) at the cathode, oxidation of EDTA within the Ni-EDTA complex at the anode was a prerequisite for Ni removal. The oxidation of metal-bound EDTA and free EDTA was driven by •OH and direct electron transfer on the PbO2 anode surface and graphite anode, respectively. We further show that ME system performs well for all pH conditions, treatment of real wastewaters as well as wastewaters containing other metals ions (Cr and Zn) along with Cu/Ni. The separation efficiency of Cu and Ni is dependent on applied electrode potential as well as nature and concentration of binding ligand present with comparatively lower separation efficiency achieved in the presence of weaker binding capacity and/or at lower ligand concentration and lower applied electrode potential. As such, some optimization of electrode potential is required depending on the nature/concentration of ligands in the wastewaters. Overall, this study provides new insights into the design and operation of EAOP technology for effective organic abatement and metal recovery from wastewaters containing mixtures of various metal-organic complexes.

Fabrication of a highly active β-PbO2-Co3O4 electrode for zinc electrowinning by pulse electrodeposition: Characterization and catalytic performance analysis

High oxygen evolution overpotential and low corrosion resistance are regarded as the main drawbacks of anode materials in zinc electrowinning. To improve the electrocatalytic activity of oxygen evolution reactions (OER) and reduce energy consumption in zinc electrowinning, a Co3O4 nanoparticle-modified PbO2 anode was prepared on a Ti substrate with Sn-SbOX as an interlayer through pulse electrodeposition. The surface morphology, phase composition, and electrochemical properties of the as-prepared anode were systematically investigated. The introduction of Co3O4 nanoparticles refined the crystal size of PbO2 and increased the surface roughness of the anode. Electrochemical tests suggested the excellent electrocatalytic activity of the Co3O4 nanoparticle-modified PbO2 anode. Density functional theory (DFT) calculations revealed that Co3O4 nanoparticles reduced the OER free energy (1.58 eV) and that pulse electrodeposition reduced the PbO2 crystal size and increased the active surface area of the anode. In the simulated zinc electrowinning test, an improved current efficiency (90.6 %) was achieved, and the low energy consumption (2,508.29 kW·h) for zinc production per ton was significantly reduced as compared with that for the conventional Pb-0.75 %Ag anode. The lifetime of the modified electrode is increased by approximately 36.8 %. This provides a reference for the design and development of anode materials with high oxygen evolution activity and strong corrosion resistance in zinc electrowinning systems.

Degradation of polyvinyl chloride microplastics via electrochemical oxidation with a CeO2–PbO2 anode

As an emerging organic pollutant, microplastics (MPs) pose a serious threat to the water environment and human health. Effective water treatment processes are urgently needed to remove MPs from the aquatic environment. Herein, an electrocatalytic oxidation system with a CeO2-modified PbO2 anode (marked as CeO2–PbO2) was proposed for the degradation of polyvinyl chloride microplastics (PVC-MPs). When the CeO2 concentration in the electrodeposition solution was 0.005 M, the obtained CeO2–PbO2 electrode had the best electrocatalytic activity due to its denser structure, higher oxygen evolution potential, and more active sites. After 6 h of electrolysis, the weight loss of PVC-MPs at the CeO2–PbO2-0.005 anode was 38.67%, greatly higher than 16.67% at the pristine PbO2 anode. To explore the degradation mechanism of PVC-MPs, the surface morphologies, elemental states, and functional groups of PVC-MPs were compared before and after electrochemical treatment, and the formed intermediates were identified. Experimental results revealed that the PVC backbones were broken, the CC double bonds were oxidized or oxidatively cleaved into small molecules, and the dechlorination reaction occurred in the electrochemical oxidation process. As a result, the particle size of the PVC-MPs decreased significantly, lots of cracks appeared and many small pieces were formed on the surface of the PVC-MPs.

Boosted electrocatalytic oxidation of organophosphorus pesticides by a novel high-efficiency CeO2-Doped PbO2 anode: An electrochemical study, parameter optimization and degradation mechanisms

This article presents a novel and highly efficient electrocatalytic degradation method for two significant organophosphorus pesticides, fenitrothion (FEN), and methyl parathion (MPN), using a Ti/β-PbO2-CeO2 modified anode (indirect oxidation). A comprehensive electrochemical investigation was also carried out to gain new insight into the redox behavior and destruction pathway of these pesticides (direct oxidation). The study also explores the effects of various operating parameters, such as initial solution pH, applied current density, and initial pesticides concentration, on the conversion-paired electrocatalytic removal process. To further enhance the degradation efficiency, a new configuration of the electrochemical cell was designed, employing two types of electrodes and two independent power supply devices. The conversion paired electrocatalytic degradation process of these pesticides involves first the direct reduction of FEN (or MPN) on a graphite cathode and then the indirect oxidation of reduced FEN (or MPN) by hydroxyl radicals electro generated on the Ti/β-PbO2-CeO2 anode. The synergism of these two processes together will effectively lead to FEN (or MPN) degradation. The degradation percentages of 98% for FEN and 95% for MPN at the optimal conditions for the electrochemical degradation of these pesticides were achieved at pH = 7, initial concentration 50 mg L−1, with a current density of 90 mA cm−2 for direct reduction and 11 mA cm−2 for indirect oxidation. Overall, this study presents a promising and efficient approach for the remediation of organophosphorus pesticide-contaminated environments, offering valuable insights into the electrochemical degradation process and highlighting the potential for practical application in wastewater treatment and environmental protection.

Y-mediated optimization of 3DG-PbO2 anode for electrochemical degradation of PFOS

In our previous study, the three-dimensional graphene-modified PbO2 (3DG-PbO2) anode was prepared for the effective degradation of perfluorooctanesulfonat (PFOS) by the electrochemical oxidation process. However, the mineralization efficiency of PFOS at the 3DG-PbO2 anode still needs to be further improved due to the recalcitrance of PFOS. Thus, in this study, the yttrium (Y) was doped into the 3DG-PbO2 film to further improve the electrochemical activity of the PbO2 anode. To optimize the doping amount of Y, three Y and 3DG codoped PbO2 anodes were fabricated with different Y3+ concentrations of 5, 15, and 30 mM in the electroplating solution, which were named Y/3DG-PbO2-5, Y/3DG-PbO2-15 and Y/3DG-PbO2-30, respectively. The results of morphological, structural, and electrochemical characterization revealed that doping Y into the 3DG-PbO2 anode further refined the β-PbO2 crystals, increased the oxygen evolution overpotential and active sites, and reduced the electron transfer resistance, resulting in a superior electrocatalytic activity. Among all the prepared anodes, the Y/3DG-PbO2-15 anode exhibited the best activity for electrochemical oxidation of PFOS. After 120 min of electrolysis, the TOC removal efficiency was 80.89% with Y/3DG-PbO2-15 anode, greatly higher than 69.13% with 3DG-PbO2 anode. In addition, the effect of operating parameters on PFOS removal was analyzed by response surface, and the obtained optimum values of current density, initial PFOS concentration, pH, and Na2SO4 concentration were 50 mA/cm2, 12.21 mg/L, 5.39, and 0.01 M, respectively. Under the optimal conditions, the PFOS removal efficiency reached up to 97.16% after 40 min of electrolysis. The results of the present study confirmed that the Y/3DG-PbO2 was a promising anode for electrocatalytic oxidation of persistent organic pollutants.

Development of SDS-Modified PbO2 Anode Material Based on Ti3+ Self-Doping Black TiO2NTs Substrate as a Conductive Interlayer for Enhanced Electrocatalytic Oxidation of Methylene Blue.

Efficient and stable electrode materials are urgently required for wastewater treatment in the electrocatalytic degradation of toxic and refractory organic pollutants. Ti3+ self-doping black TiO2 nanotube arrays (Ti/B-TiO2-NTs) as an interlayer were used for preparing a novel PbO2 electrode via an electrochemical reduction technology, and a sodium dodecyl sulfate (SDS)-modified PbO2 catalytic layer was successfully achieved via an electrochemical deposition technology. The physicochemical characterization tests showed that the Ti/B-TiO2-NTs/PbO2-SDS electrodes have a denser surface and finer grain size with the introduction of Ti3+ in the interlayer of Ti/TiO2-NTs and the addition of SDS in the active layer of PbO2. The electrochemical characterization results showed that the Ti3+ self-doping black Ti/TiO2-NTs/PbO2-SDS electrode had higher oxygen evolution potential (2.11 V vs. SCE), higher electrode stability, smaller charge-transfer resistance (6.74 Ω cm-2), and higher hydroxyl radical production activity, leading to it possessing better electrocatalytic properties. The above results indicated that the physicochemical and electrochemical characterization of the PbO2 electrode were all enhanced significantly with the introduction of Ti3+ and SDS. Furthermore, the Ti/B-TiO2-NTs/PbO2-SDS electrodes displayed the best performance on the degradation of methylene blue (MB) in simulated wastewater via bulk electrolysis. The removal efficiency of MB and the chemical oxygen demand (COD) could reach about 99.7% and 80.6% under the optimal conditions after 120 min, respectively. The pseudo-first-order kinetic constant of the Ti/B-TiO2-NTs/PbO2-SDS electrode was 0.03956 min-1, which was approximately 3.18 times faster than that of the Ti/TiO2-NTs/PbO2 electrode (0.01254 min-1). In addition, the Ti/B-TiO2-NTs/PbO2-SDS electrodes showed excellent stability and reusability. The degradation mechanism of MB was explored via the experimental identification of intermediates. In summary, the Ti3+ self-doping black Ti/TiO2-NTs/PbO2-SDS electrode is a promising electrode in treating wastewater.

A cyclone reactor of electrochemical advanced oxidation processes using PbO2 anode and H2O2 electrosynthesis cathode

Electrochemical advanced oxidation processes are promising tools for pollution abatement but most still lack practical engineering attempts and devices. A type of process intensification reactor for the electrochemical advanced oxidation processes is developed here. The cyclone continuous flow electrochemical reactor adopts a PbO2 anode and H2O2 electrosynthesis cathode together. A lab-scale cyclone continuous flow electrochemical reactor is fabricated and simulated, which is evaluated using the H-acid wastewater. The contributions of the PbO2 anode and H2O2 electrosynthesis cathode to pollutant degradation are discussed particularly. A 3-D model is developed to provide a visualized perspective on the reactor performances, including flow distribution, mass transfer, and current distribution. Pronounced signals of powerful radicals can be detected for the PbO2H2O2 cyclone reactor, including •OH, SO4•−, and 1O2. It exhibits excellent performances on mass transfer, electrical properties, organic degradation, and space-time yield. Such a strategy presents a promising engineering solution for scale-up and further development toward industrial application.

Characterization of a Ti/SnO2-Sb/Fe-PVP-PbO2 Electrode Deposited from Methanesulfonate Bath and Application in Electrocatalytic Degradation of MO

Ti/SnO2-Sb/PbO2 anodes were electrodeposited from methanesulfonate-based baths, and the effect of dopants such as PVP and Fe on the surface morphology, phase composition, electrocatalytic activity and stability was investigated. It is revealed that the inclusion of Fe effectively enhances the stability of PbO2 anode, while PVP can significantly improve its electrocatalytic activity. The Fe,PVP-codoped anode, Ti/SnO2-Sb/Fe-PVP-PbO2, exhibits the higher stability and electrocatalytic activity compared to the respective inclusion of Fe and PVP. The gradation efficiency of methyl orange (MO) on the Ti/SnO2-Sb/Fe-PVP-PbO2 anode is affected by the applied current density and the initial MO concentration. During degradation, the azo structure of MO is firstly cleaved, resulting in the rapid decolorization of solution. Demethylated MO and the anion of sulfanilic acid are detected as intermediates, and thus a plausible pathway of MO degradation is proposed.