PbO2 Electrode Research Articles

Electrochemical degradation of dye on lead dioxide electrodeposited on stainless steel: effect of cyclic voltammetry parameters

The effect of cyclic voltammetry (CV) on electrochemical behavior of PbO2 layer electrodeposited by pulsed method on stainless steel (AS30) has been studied. The field emission scanning electrons microscope and X-ray diffraction (XRD) were used to characterize the surface morphology and crystal structure of different electrodes with CV effect, respectively. The content of PbO2 particles has been tuned by altering the cycle number, of CV through which the content of PbSO4 also increased. It is related to reduction phenomena depending on electron transfer through the pores into β-PbO2 layer. Electrochemical behavior of the prepared samples was investigated in 0.5M H2SO4 solution by CV and electrochemical impedance spectroscopy (EIS) techniques. EIS results revealed that the charge-transfer resistance significantly increased because the lead sulfate layer is more compact and the access of electrolyte ions to the internal layer is blocked. Anodic oxidation of solutions containing Amaranth as a dye model was studied to evaluate the use of these electrodes as anodes in environmental issue. After five cycle of CV, PbO2 film becomes more resistive according to value of Rf and this may have a deleterious effect on the electrochemical degradation activity compared to that without CV treatment. Based on the obtained results, after electrolysis time of 5 h at acidic pH medium, the color and the chemical oxygen demand removals on PbO2 electrode treated by 1 CV achieved nearly to 97 and 83%, higher than that without CV treatment (77 and 47%), respectively.

A comparison of electrochemical oxidation performance of PbO2 and SnO2 electrodes

PbO2 and SnO2 are two promising anode materials for electrochemical oxidation. In order to highlight the difference between two kinds of electrodes in an electrochemical oxidation process, their morphology, structural, oxygen evolution overpotential (OEP), electrochemical activity and service life-time were compared in detail in this paper. Surface characterization by scanning electron microscope shows that the film of the PbO2 electrode is even, compact, non-porous, and non-cracked, while many cracks are present on the film of the SnO2 electrode. Electrochemical studies based on linear sweep voltammetry (LSV) and cyclic voltammetry (CV) prove that the OEP for the SnO2 electrode was much higher than that of the PbO2 electrode, and the electron-transfer kinetics and the reversibility of electrode reaction of the SnO2 electrode were superior to those of the PbO2 electrode. In electrochemical decomposition of p-nitrophenol, the degradation ratios at PbO2 and SnO2 anodes achieved 86.9% and 96.5%, respectively, after 120 min electrolysis, which verified the results of LSV and CV. The accelerated lifetime tests show that the service life time of the SnO2 electrode is far shorter than that of the PbO2 electrode, even though it was shown to be superior to the PbO2 in electrocatalytic activity.

Fabrication and Characterization of a PbO2-TiN Composite Electrode by Co-Deposition Method

An excellent PbO2 electrode with high electrocatalytic activity and stability was successfully fabricated by doping TiN particles through co-deposition method (marked as PbO2-TiN). The morphology (SEM), crystalline structure (XRD), chemical state (XPS), electrochemical performances (CV and EIS) and stability (accelerated life test) were characterized. The results showed that TiN doping could obviously improve the surface morphology of the electrode, increase the electrode current response and reduce the electrode impedance. During the electrochemical oxidation process, the PbO2-0.5TiN electrode showed the best performance on degradation of Acid Red G and Methylene blue (the highest removal efficiency, the lowest energy consumption and minimum Pb dissolution). The proportion of adsorbed hydroxyl oxygen for PbO2-0.5TiN electrode was 78.75%, which was higher than that for PbO2 electrode (68.95%). The accelerated service lifetime of PbO2-0.5TiN electrode was 302 h, which was more than 3 times longer than that of PbO2 electrode (96 h). Furthermore, a likely deactivation mechanism for lifetime enhancement of PbO2-0.5TiN electrode was proposed.

Development of Three-Dimensional Electrodes of PbO2Electrodeposited on Reticulated Vitreous Carbon for Organic Eletrooxidation

The application of electrochemical technology for the degradation of organic pollutants often faces two main problems, related to the anode material and mass transport limitations. Although PbO2 electrode is inexpensive and provides satisfactory electrooxidation kinetics, in the form of plane electrodes it is unable to resolve the mass transfer problem that arises at low concentrations of organics. In this work, an electrochemical flow reactor was developed for the preparation of three-dimensional electrodes consisting of PbO2 films electrodeposited onto reticulated vitreous carbon. The electrodes were characterized in terms of the substrate coating, morphology, structure, and electrocatalytic activity in the decoloration reaction of Reactive Blue 19 dye. The results showed that it was possible to deposit a uniform film of PbO2 on the surface of the substrate after optimization of the current density and deposition time (0.7 mA cm-2 for 30 min). Comparison of the plane and three-dimensional electrodes revealed that the turbulence generated by the porous matrix significantly accelerated the dye decoloration kinetics, increasing 3.3-fold the first order kinetic constant (from 0.010 min-1 for VC/PbO2 to 0.033 min-1 for RVC/PbO2).

Fabrication and characterization of a novel PbO2 electrode with a CNT interlayer

A novel PbO2 electrode (marked as CNT–PbO2) with a carbon nanotube (CNT) interlayer was prepared by electrophoretic deposition and electro-deposition.

Electrocatalytic degradation of ibuprofen in aqueous solution by a cobalt-doped modified lead dioxide electrode: influencing factors and energy demand

PbO2 electrode modified with Co exhibited higher electrochemical oxidation. The effects of HA, FA, OA and CA were investigated.

Electrochemical oxidation of cinnamic acid with Mo modified PbO2 electrode: Electrode characterization, kinetics and degradation pathway

A novel molybdenum modified PbO2 electrode was successfully prepared with the method of electrodeposition. The SEM and XRD were employed to study the surface morphology of electrodes, which indicated that the modified PbO2 electrode had a larger effective area and more compact film. Electrochemical degradation of cinnamic acid (CA) in aqueous solution with Mo–PbO2 electrode and PbO2 electrode were investigated. The results showed that the Mo–PbO2 electrode had a better effect of CA removal. The operational parameters influencing the electrochemical degradation of CA with Mo–PbO2 electrode were optimized and the results revealed that the electrochemical degradation of CA followed the pseudo-first-order kinetics and the optimal removal of CA and COD were 85.51% and 25.79% after 120min on condition of the electrolyte concentration, initial concentration of CA, current density and initial value of pH were 0.1mol/L, 300mg/L, 10mA/cm2 and 3.4, respectively. The degradation mechanism of CA in electrochemical oxidation with Mo–PbO2 electrode was analyzed and the main degradation pathway of CA was proposed based on the intermediates identified by IC and GC–MS.

Degradation of azo dye C.I. Acid Red 18 using an eco-friendly and continuous electrochemical process

Continuous anodic oxidation of azo dye C.I. Acid Red 18 by using PbO2 electrode in aqueous solution was studied. To reach the best conditions of the process, the influence of various operating parameters such as pH, current density, hydraulic retention time (HRT) and dye concentration on the removal rate of chemical oxygen demand (COD) and color, as indexes showing the amount of efficiency, was investigated. The findings showed that, respectively, 99.9% and 80.0% of the dye and COD were removed (at optimized conditions). Mineralization current efficiency results indicated that at the beginning of the reaction mineralization occurred quickly at a low current density, whereas at high amounts the rate of mineralization the efficiency decreased. At the optimum conditions, the majority of COD was removed only with 38.2 kWh/kg COD of energy consumption in 120 min. By controlling HO•/dye concentration ratio via the parameters adjustment, particularly HRT and current density, this system can treat Acid Red 18 well even at high concentrations. Furthermore, the voltammetry study illustrated that electroactive intermediates created during the process were mineralized at current density of 8.6mA/cm2.

Properties of Fluoride-Doped p -PbO2 Electrodes and their Electrocatalytic Activities in Degradation of Acid Orange II

Properties of Fluoride-Doped p -PbO2 Electrodes and their Electrocatalytic Activities in Degradation of Acid Orange II

Mechanism of enhanced electrochemical degradation of highly concentrated aspirin wastewater using a rare earth La-Y co-doped PbO2 electrode

A novel La-Y-PbO2 electrode was prepared by electrodeposition technique and the degradation mechanism for aspirin was explored. In contrast with the PbO2 electrode, La-PbO2 electrode and Y-PbO2 electrode, La-Y-PbO2 electrode displayed a more compact surface with a smaller grain size of crystal, accompanying with increased concentration of active oxygen species. The higher voltammetric charge quantity of La-Y-PbO2 electrode indicated its larger electrochemical active surface area and higher electrochemical activity. The La-Y-PbO2 electrode was demonstrated to have a superior electrochemical oxidation ability, which had a higher apparent rate constant, mass transport and mineralization current efficiency and lower energy consumption. The evolution of intermediates and the aspirin degradation mechanism were further discussed. Meanwhile, high reusability and safety were achieved by La-Y-PbO2 electrode when treating aspirin wastewater.

Electrocatalytic Degradation of Methyl Orange on PbO2-TiO2 Nanocomposite Electrodes

The electrocatalytic degradation of methyl orange (MO) on PbO2-TiO2 nanocomposite electrodes was studied by cyclic voltammetry and bulk electrolysis. The results reveal that PbO2-TiO2 nanocomposite electrodes possess higher oxygen evolution overpotential than PbO2 electrodes and the electrocatalytic degradation of MO on the electrodes is direct oxidation process. The influence of experimental parameters, such as current density, initial MO concentration, initial pH value and Na2SO4 concentration, on the MO removal efficiency was studied in order to optimize the electrochemical oxidation process. The results show that the MO and COD removal efficiency in 0.1 mol/L Na2SO4 solution containing 30 mg/L MO could reach 95.5 % and 77.2% with current density 30 mA/cm2 after 240 min. Compared with PbO2 electrodes, the PbO2-TiO2 nanocomposite electrodes show higher COD removal efficiency and instantaneous current efficiency with MO degradation. The experimental results demonstrate that electrochemical oxidation on PbO2-TiO2 nanocomposite electrodes is a suitable method for treatment of water polluted with organic pollutants.

Degradation Characteristics of Cationic Red X-GRL with Gd, La Co-doped PbO2 Electrode

To enhance the degradation efficiency as purpose, the Gd2O3 and La2O3 were doped in the lead dioxide electrode by the thermal decomposition and electro-deposition technique for the treatment of simulated wastewater containing cationic red X-GRL (X-GRL). The optimized molar ratio of Pb:Gd:La of 200mol:3mol:1mol, and the optimal degradation conditions of current density 50 mA/cm2, 0.1 mol/L Na2SO4, initial quality concentration of X-GRL 100 mg/L, after 2 h degradation, the X-GRL and TOC removal of reached 97.81% and 51.28%, respectively. The efficiency of combustion (ηc) of rare earth co-doped electrode was increased by 0.257 than that of un-doped electrode.

Batch and continuous flow anodic oxidation of 2,4-dinitrophenol: Modeling, degradation pathway and toxicity

Being a priority pollutant, complete degradation of 2,4-dinitrophenol (2,4-DNP) is recommended. This study attempts the electrochemical oxidation of 2,4-DNP using a novel PbO2 electrode. Multiparameter optimization is studied to elucidate the interactive role of parameters on the degradation. The critical operational parameters and its range of operation were identified using uniparameter studies in a batch reactor as NaCl concentration (0.5–1.5 g L− 1), current density (0.96–1.91 mA cm− 2) and pH (4–8). The operational range was further optimized using response surface methodology as NaCl concentration of 0.08–1.4 g L− 1 at pH of 4.5 to 8 and a current density of 1.2 to 1.79 mA cm− 2. Maximum COD removal efficiency was predicted as 94.2% at a pH of 6.59, NaCl concentration of 1.12 g L− 1 and current density of 1.44 mA cm− 2, which upon experimentation was obtained as 93.9%. Complete degradation of the contaminant was obtained within 150 min in a continuous flow reactor at a flow rate of 500 mL h− 1 with NaCl concentration of 0.5 g L− 1 and current density of 1.44 mA cm− 2. Intermediates of the reaction were identified as benzoquinone, hydroquinone, catechol, 4-nitrocatechol and 2-nitrobenzoquinone using high performance liquid chromatography (HPLC) and mass spectroscopy (MS) analysis. Ion chromatography analysis showed nitrate removal to be one of the foremost steps in the degradation. Cytotoxicity of the intermediates was found to be lesser than that of 2,4-DNP. The results show feasibility for field application of the tested method for the degradation of 2,4-DNP.

Fabrication, characterization and electrocatalytic application of a lead dioxide electrode with porous titanium substrate

In this study, PbO2 electrode was prepared on porous Ti/SnO2–Sb2O5 substrate (denoted as 3D-Ti/PbO2 electrode), and its electrochemical properties were investigated in detail. The electrodeposition mechanism of 3D-Ti/PbO2 electrode was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Scanning electron microscope (SEM) result showed that the 3D-Ti/PbO2 electrode possessed porous structure when it was electrodeposited for time less than 30 min. The 3D-Ti/PbO2 electrode prepared for 10 min had more active sites than the lead dioxide electrode electrodeposited on planar titanium substrate (denoted as 2D-Ti/PbO2 electrode) and its electrochemical porosity is about 54%. The embedded structure between porous Ti/SnO2–Sb2O5 substrate and PbO2 coating increased the stability of 3D-Ti/PbO2 electrode. The service life of 3D-Ti/PbO2 electrode was about 350 h which was much longer than 2D-Ti/PbO2 electrode. What's more, 3D-Ti/PbO2 electrode had better electrocatalytic activity towards phenol degradation than 2D-Ti/PbO2 electrode.

Potentiostatic electrodeposition of a novel cost effective PbO2 electrode: Degradation study with emphasis on current efficiency and energy consumption

Electrochemical oxidation is developing as a prominent technology for the degradation of organic contaminants. Even though many electrode materials proved efficient in degradation of organics, the quest for a stable, low cost electrode material is still at large. The present study attempted the development of an efficient and cost effective electrode material, PbO2 electrodeposited on mild steel. The optimum operating range of parameters for the electrodeposition was established. Compact structure of PbO2 was obtained up to an applied voltage of 2V. Concentration of PbO also affected the morphology at lower concentration. XRD analysis depicted that the deposit consists of a mixture of α and β-PbO2, and non-stoichiometry of the deposited PbO2 was proved by EDX analysis. Applied current, initial dye concentration, supporting electrolyte type and concentration affected the reaction kinetics, current efficiency and energy consumption in the degradation of methyl orange on MS/PbO2 electrode. A current efficiency of 57% and corresponding energy consumption of 42kWhkgCOD−1 treated was obtained at 88% COD degradation for an initial COD of 292mgL−1 with current density of 2.87mAcm−2. The newly developed MS/PbO2 electrode had current efficiency and energy consumption comparable with data reported in literature at similar degradation conditions.

Electrocatalytic activity of Ce-PbO2/C anode for acid red B reduction in aqueous solution

Graphite–lead dioxide electrodes doped with rare earth Cerium (Ce-PbO2/C electrodes) were prepared by electrodeposition. The scanning electron microscope results showed that the microstructure and crystal orientation of electrode surface were changed by Cerium doping. CeO2 was detected from modified electrodes by X-ray diffraction analysis. The cyclic voltammetry spectra indicated that the oxidation peak potential of cerium-doped electrode was smaller than pure PbO2 electrode. Effects of the novel electrode on acid red B degradation were evaluated systematically under different parameters, including applied voltage, initial pH, supporting electrolyte concentration, electrode spacing, and influent concentration. The results indicated that chemical oxygen demand, decolorization, and ammonia nitrogen removal rate of Ce-PbO2/C electrodes reached 90.17, 99.98, and 97.23 %, respectively, after 60-min electrolysis at initial 1000 mg L−1 acid red B concentration. The possible mechanism of acid red B degradation over Ce-PbO2/C electrodes was monitored by gas chromatography-mass spectrometer.

Preparation and characterization of Ce and PVP co-doped PbO2 electrode for waste water treatment

In this study, the novel PbO2 electrodes co-doped with rare earth (Ce) and polyvinylpyrrolidone (PVP) were prepared by electrodeposition technique. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used to characterize the surface morphology and crystal structure of the electrodes. In contrast with PbO2, Ce–PbO2, PVP–PbO2 and Ce–PVP–PbO2 electrodes, the Ce–PVP–PbO2 electrode had smaller crystal particles and more compact structure. The electro-catalytic activity of electrodes was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that the prepared Ce–PVP–PbO2 electrode has lower energy consumption and more excellent electrochemical oxidation performance than other three kinds of electrodes. Electrochemical oxidation methyl orange as a model dye wastewater was studied to evaluate the potential applications of this electrode in environmental science. It was found that the Ce–PVP–PbO2 electrode exhibited higher decolorization and COD removal efficiency than other three kinds of electrodes.

Electrochemical degradation of chloramphenicol with a novel Al doped PbO2 electrode: Performance, kinetics and degradation mechanism

This study presents an electrochemical method for the degradation of chloramphenicol (CAP) in aqueous solution with a novel Al doped PbO2 electrode. The Al-doped PbO2 electrode showed high electrochemical activity, oxygen evolution potential, radical utilization rate, reusability and safety. The influence factors on CAP degradation with the Al-doped PbO2 electrode were investigated in detail, and under the optimal conditions the removal rates of CAP and TOC reached 87.30% and 52.06% in acid conditions after 2.5h electrolysis with a 0.2moldm−3 Na2SO4 at a current density of 30mAcm−2, respectively. The electrochemical degradation of CAP at Al-doped PbO2 electrode electrode followed pseudo-first-order kinetics. The degradation mechanism was proposed by cyclic voltammograms tests and it was deduced that hydroxyl radicals generated in the electrochemical process played a key role in oxidizing CAP. Finally, based on the reaction products identified, a possible degradation pathway including radical reaction, ring open and mineralization was proposed.

Electrochemical degradation of aspirin using a Ni doped PbO2 electrode

The novel nickel modified PbO2 electrodes were successfully prepared via electrodeposition in nitrate solution. The influence of nickel content on the physico-chemical properties and electrocatalytic performance of PbO2 electrodes was investigated. The electrodes were characterized by SEM, EDX and XRD techniques. A limited amount of doping nickel could produce a more compact PbO2 film and diminish the size of the crystal grains. The steady-state polarization curves and the cyclic voltammetry analysis showed that the 1% Ni–PbO2 electrode had the highest oxygen evolution potential and the optimal electrochemical oxidation ability. The cyclic voltammograms with various scan rates showed that the oxidation of aspirin on these PbO2 electrodes was a typical diffusion-controlled electrochemical process. Stability tests of different PbO2 electrodes showed that 1% Ni–PbO2 electrode had the highest electrochemical stability. In addition, nickel modified PbO2 electrodes were used to degradation aspirin in aqueous solution, which gave the direct evidence of the electrocatalytic capabilities of these electrodes. The results showed that 1% Ni–PbO2 electrode obtained the highest kinetic rate constant, chemical oxygen demand (COD) and total organic carbon (TOC) removals, which were 1.41, 1.22, 1.20times than those of undoped PbO2 electrode, respectively. Moreover, the energy required for the treatment of 1m3 aspirin solution significantly decreased and the hydroxyl radical utilization rate was enhanced after appropriate nickel doping. As a result, the 1% Ni–PbO2 electrode is a promising anode for the treatment of organic pollutants.

Fabrication and characterization of PbO2 electrode modified with [Fe(CN)6]3− and its application on electrochemical degradation of alkali lignin

PbO2 electrode modified by [Fe(CN)6]3− (marked as FeCN–PbO2) was prepared by electro-deposition method and used for the electrochemical degradation of alkali lignin (AL). The surface morphology and the structure of the electrodes were characterized by scanning electronic microscopy (SEM) and X-ray diffraction (XRD), respectively. The stability and electrochemical activity of FeCN–PbO2 electrode were characterized by accelerated life test, linear sweep voltammetry, electrochemical impedance spectrum (EIS) and AL degradation. The results showed that [Fe(CN)6]3− increased the average grain size of PbO2 and formed a compact surface coating. The service lifetime of FeCN–PbO2 electrode was 287.25h, which was longer than that of the unmodified PbO2 electrode (100.5h). The FeCN–PbO2 electrode showed higher active surface area and higher oxygen evolution potential than that of the unmodified PbO2 electrode. In electrochemical degradation tests, the apparent kinetics coefficient of FeCN–PbO2 electrode was 0.00609min−1, which was higher than that of unmodified PbO2 electrode (0.00419min−1). The effects of experimental parameters, such as applied current density, initial AL concentration, initial pH value and solution temperature, on electrochemical degradation of AL by FeCN–PbO2 electrode were evaluated.