Lead Dioxide Anode Research Articles

Depollution of 1,3,5-trimethoxybenzene through its electrochemical conversion into a high added value product 2,6-dimethoxy-1,4-benzoquinone

The first part of this work relates to the analytical study of the electrochemical behavior of 1,3,5-trimethoxybenzene (TMB) by cyclic voltammetry at treated gold electrode. The second part is relative to the results of its conversion into a high added value product 2,6-dimethoxy-1,4-benzoquinone (DMBQ) by electrolysis at lead dioxide anode. The used electrolyte which is a simulated solution of TMB in water–acetone mixture should be prepared using a preconcentrated TMB wastewater. The partial substitution of water by acetone permit to control the TMB solubility to avoid the electrochemical efficiency reduction by TMB transfer limitation. Moreover, the DMBQ desorption from the electrode surface by the effects of acetone and its displacement by TMB provides the slowdown of its degradation. The electrochemical DMBQ recovery increases with the enhancement of acetone volumic percentage and decreases by increasing the current density.

Indirect electrochemical oxidation of aniline in acid electrolyte with active oxygen species

Kinetics and selectivity of the aniline oxidation on a boron-doped diamond electrode and lead dioxide anode (Pb/PbO2) in an acid electrolyte were studied under various generation conditions of active oxygen species. The resulting kinetic dependences can be described by a pseudo-first-order equation. The apparent rate constants of the process were determined for two electrolysis modes: direct anodic oxidation and oxidation with addition of hydrogen peroxide. UV spectroscopy was used to determine that the aniline destruction process occurs via formation of a number of intermediate products (benzoquinone, carboxylic acids). It was shown that the aniline destruction process can occur with a rather high efficiency (~80–90%) on the electrode types under study.

Electrochemical Oxidation of Environmentally Persistent Perfluorooctane Sulfonate by a Novel Lead Dioxide Anode

Ti/TiO2-NTs/Ag2O/PbO2 anode was prepared by electrodeposition technique and characterized by scanning electron microscope-energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), linear sweep voltammetry (LSV), and accelerated life test. Electrochemical oxidation of persistent organic pollutant wastewater perfluorooctane sulfonate (PFOS) was carried out with the novel PbO2 anode. Ti/TiO2-NTs/Ag2O/PbO2 anode exhibited a pyramid structure, which was the typical PbO2 electrodes prepared using electrochemical deposition method. XRD spectra indicated that diffraction peaks of PbO2 coating conformed to that of JCPDS (Joint Committee on Powder Diffraction Standards) card for β-PbO2. Ti/TiO2-NTs/Ag2O/PbO2 anode showed high oxygen evolution potential, and longer life service, compared with Ti/PbO2 and Ti/TiO2-NTs/PbO2 anodes. The degradation ratio of PFOS (90mL of 0.0929mmolL−1) was 74.87%, with a pseudo first-order kinetic constant of 0.0165min−1 and a half-life of 43.18min−1 at a constant current density of 30mAcm−2 after 180min of electrolysis. PFOS oxidation yielded sulfate, fluoride, and perfluorocarboxyl anions (i.e., C3F7COO−, C4F9COO−, C5F11COO−, C6F13COO−, and C7F15COO−). The electrospray ionization (ESI) mass spectrum confirmed that oxygen in the intermediate products originated from a heavy-oxygen water electrolyte, and the degradation of PFOS was initiated by the dissociation of a sulfonic group. A possible mechanism was revealed; that was, PFOS was desulfated at the anode to form C8F17· and then transformed into C8F17OH, followed by intramolecular rearrangement and hydrolysis reactions to form C7F15COO−. Kolbe decarboxylation occurred in C7F15COO− at the anode to generate C7F15·, which evolved into C6F13COO− in a similar way and the CF2 unit fell off from C7F15COO−. PFOS was gradually degraded into short-chain perfluorocarboxyl anions by repeating the CF2 unzipping cycle.

Optimization of Phenol Removal Using Ti/PbO2 Anode with Response Surface Methodology

AbstractScale-up of a lead dioxide (PbO2) anode system is significant to the practical application of electrochemical oxidation (EO) in biorefractory wastewater treatment. In this study, response surface methodology (RSM) was employed to investigate the effects of different operating conditions on phenol removal by electro-oxidation with a Ti/PbO2 anode. A central composite design (CCD) was used to optimize the electro-oxidation process and to evaluate the individual and interactions effects of current intensity, electrolysis time, and recirculation flow rate on phenol removal. Synthetic wastewater (or distillate water) with phenol concentration of 10 mg/L−1 was used in this study. Optimal conditions for phenol removal were established at 1.12 A current intensity, 40 min electrolysis time, and 188 mL·min−1 recirculation flow rate, in which a removal of 78.97±1.72% was achieved. The decay kinetics of phenol removal was fitted a first-order reaction.

Electrochemical behavior of Auramine O dye in aqueous solutions at lead dioxide electrode

Electrochemical behavior of Auramine O (AO) was studied by galvanostatic electrolysis at lead dioxide (Ta/PbO 2 ) anodes. The influence of operating parameters, such as current density, initial concentration of AO, temperature and initial pH value was investigated. The oxidation kinetics of the AO was followed by HPLC, UV / visible spectrophotometry and the measurement of chemical oxygen demand (COD). The experimental results showed that the electrochemical process was suitable for almost completely removing COD, due to the production of the hydroxyl radicals at the anode surface. The oxidation of AO is dependent on its initial concentration, current density, temperature and pH. COD decay follows a pseudo first-order kinetic and the process was under mass transport control. The HPLC analysis showed that the main AO oxidation products formed during electrolysis are the hydroquinone (HQ) representing the reduced form of benzoquinone (BQ) and carboxylic acids (CA). The proposed AO anodic oxidation into (BQ) is mainly based on an alternance of indirect monoelectronic discharge by the mediation of hydroxyl radicals and hydrolysis steps. The electrochemical oxidation of AO can be used as an economically adequate way for a pre-treatment of waters containing this dye followed by biological treatment.

Anodic electrocrystallization of molybdenum(VI) doped thallium and lead oxides

Molybdenum(VI) doped oxides of p elements, such as thallium and lead, have been synthesized by anodic crystallization. Anodic precipitates based on thallium and lead oxides are shown to contain only a relatively small amount of molybdenum compounds (up to 2 at %) in contrast to mixed manganese and molybdenum oxides (Mn1 -x MoxO2 +x ⋅ nH2O) synthesized by electroprecipitation. The effect of molybdate ions on the electrocrystallization of thallium oxides is most pronounced in the region of threedimensional phase precipitate formation potentials. The introduction of molybdenum(VI) compounds into a solution during the electroprecipitation of lead dioxide induces the formation of precipitates with a much larger spe� cific surface area than individual PbO 2 . The anodic polarization on electrodes with an active layer of molyb� denum doped lead(IV) oxides in the electrolysis of acidic media considerably decreases compared with lead dioxide anodes.

Електрохімічна руйнація метилтрет-бутилового етеру

In this paper, we have examined the performance of PbO 2 anodes in the EC degradation of MTBE. It was shown that electrochemical oxidation of MTBE at lead dioxide anodes is effective method of anodic conversion of the organic pollutant to acetic acid as untoxic product. Proposed method is formally reagent treatment of water at the same time it does not need addition of any reagent in reaction media. All needed reagents formed directly from the solvent (water) thanks to electrochemical reactions. According to obtained data the main electrochemical stages of the process of anodic conversion of MTBE are formation of hydroxyl-radicals and molecular oxygen. Then formed compounds take part in stages of chemical MTBE oxidation and intermediate species that led to deeper oxidation to form acetic acid as the result. Proposed mechanism of MTBE electrochemical oxidation is in satisfactory agreement with experimental data. Dependence of MTBE conversion rate from the nature of micro-doped and composite lead dioxide anodes is explained by difference in hydroxyl-radical bond strength with an electrode surface that determined it reaction ability in secondary chemical reactions of organic compounds oxidation.

Carbon-Based Cerium(III)-Doped Lead Dioxide Anode

The electrocatalytic activity of cerium doped lead dioxide anode was investigated. The electrodes were prepared by electrodeposition of lead dioxide on the carbon based substrates from the bath comprising lead(II) nitrate 1.0 M and cerium(III) nitrate 0.1 M. Polarization studies of cerium doped lead dioxide electrodes were carried out using 1.0 mM iso-propanol at a scan rate of 100 mV/min in a three electrode system as shown in Figure 1. The electrooxidation of chromium(III) to chromium(VI) was also carried out using 0.3 mM chromium(III) solution and the cerium doped electrodes of area 30cm2 in divided cell. The electrolysis was run for 20 hours and the electrolyte was analyzed by visible spectroscopy. The electrochemical conversion of chromium(III) to chromium(VI) after electrolysis was 77.4% by passing 2.5 mF of charge.

Carbon-Based Cerium(III)-Doped Lead Dioxide Anode

Electro-catalytic activity of carbon based cerium doped lead dioxide anodes was investigated. Electrodes were prepared by electrodepositing lead dioxide on carbon based substrates from a bath comprising 1.0 M lead(II) nitrate and 0.1 M and cerium(III) nitrate. Polarization studies of cerium doped lead dioxide electrodes were carried out using 1.0 mM iso-propanol at scan rate 100 mV/min in a three electrode system as shown in Figure 1.Electro-oxidation of chromium(III) to chromium(VI) was also carried out at the cerium doped lead dioxide electrode (area 30cm2) in a divided cell using 0.3 mM chromium(III) solution. Electrolysis was run for 20 hours and the electrolyte upon analysis by visible spectrophotometry yielded 77.4% conversion of chromium(III) to chromium(VI).Figure 1: Anodic polarization curves: (a) bare carbon, (b) cerium(III)-doped lead dioxide and (c) cerium(III)-doped lead dioxide in 1.0 mM iso-propanol. Background electrolyte: 1.0 M sulphuric acid and E in volts vs. Ag/AgCl,Cl- Reference:J. Kong, S. Shi, L. Kong, X. Zhua and J. Ni, Preparation and characterization of lead dioxide electrodes doped with different rare earth oxides, Electrochim. Acta, 53, 2048 (2007)*Presently at School of Chemistry Monash University Clayton Victoria 3800 Australia

Electrochemical Degradation Pathway of Tricyclazole in Aqueous Solution Using Lead Dioxide Anode

The electrochemical degradation of tricyclazole (TC) in aqueous solution on Ti/SnO2Sb/PbO2 anodes was investigated. The degradation efficiency and mineralization rate was studied. Kinetic analyses indicated that the electrochemical degradation followed a pseudo-first-order reaction. The mineralization intermediates were analyzed by chromatographic techniques. Finally, a pathway for electrochemical degradation of TC in aqueous medium was proposed.

Fabrication of cerium-doped lead dioxide anode with improved electrocatalytic activity and its application for removal of Rhodamine B

The electrochemical properties of a titanium dioxide nanotubes/cerium-doped lead dioxide (TiO2-NTs/Ce-PbO2) anode and its removal of Rhodamine B (RhB) from aqueous solution were investigated. Cerium doping content and electrodeposition time were optimized to get the highest electrocatalytic activity. Scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy were used to characterize the morphology, crystal structure and elemental states of the modified anode. The accelerated life test and linear sweep voltammetry indicated that TiO2-NTs/Ce-PbO2 possessed 2.3 times longer accelerated service life and higher oxygen evolution potential than TiO2-NTs/PbO2. The removal of RhB by TiO2-NTs/Ce-PbO2 anode was investigated under different conditions. It was found that a higher current density, acidic or quasi-neutral solution and the presence of chloride ions promoted the removal efficiency of RhB. The good electrocatalytic performance of TiO2-NTs/Ce-PbO2 makes it a promising anode for treatment of organic pollutants in aqueous solution.

Effect of Electrochemical Modification Method on Structures and Properties of Praseodymium Doped Lead Dioxide Anodes

A lead dioxide anode doped with the praseodymium was prepared by a simple method of cyclic voltammetry (CV). Then the major work focused on the investigation of the different electrochemical performance of praseodymium doped lead dioxide anode by CV method and coelectrodeposition (CD) method. The spectral methods and electrochemical measurements were applied to analyze the physicochemical properties of the Ti/PbO2-Pr2O3 anodes prepared by the two methods. The XRD and XPS showed the Pr2O3 was successfully doped into the PbO2 film by CV method. Comparative studies between the two doped anodes indicated that the Ti/PbO2-Pr2O3 (CV) anode had a larger surface, a better stability and exhibited a longer service life. The experiments of degradation methyl orange as a model dye wastewater suggested that comparing with Ti/PbO2-Pr2O3 (CD) anode, Ti/PbO2-Pr2O3 (CV) anode had excellent electrocatalytic performance and low energy consumption. Thus, the CV modification method should be considered as a simple and promising modification method for the rare earth elements doped on the surface of many other anodes.

Advanced oxidation process for the removal of ionic liquids from water: The influence of functionalized side chains on the electrochemical degradability of imidazolium cations

Advanced oxidation processes can assist in the elimination of imidazolium-based ionic liquids (ILs) from water. With the aid of electrocatalytic degradation at a lead dioxide anode, it was shown that the degradation rate of these ILs from aqueous solutions was dependent on a change in the nature of the side chains in the cation. All the ionic liquids were efficiently oxidized within 240min. Even the mineralization of ILs was high up to 97% depending on structure. Cyclic voltammetry indicated that ILs were oxidized indirectly by radicals generated on the anode surface. HPLC-UV and electrospray mass spectroscopy analysis suggest that ILs undergo degradation along a pathway involving intermediates produced as a result of hydroxyl radical substitution to side chain and by oxidative cleavage of the imidazolium ring. The probability of imidazolium core attack by OH radicals increased with decreasing length of the substituted side chain.

Fabrication and electrochemical treatment application of a microstructured TiO2-NTs/Sb–SnO2/PbO2 anode in the degradation of C.I. Reactive Blue 194 (RB 194)

A microstructured Sb-doped SnO2/PbO2 electrode was synthesized and investigated for the treatment of C.I. Reactive Blue 194 (RB 194) in aqueous solution. An electrochemical method was employed for the electrodeposition of PbO2 on an ordered microstructured TiO2-NTs template to obtain a large specific surface area and high space utilization. The TiO2-NTs/Sb–SnO2/PbO2 electrode was characterized by XRD, SEM and cyclic voltammetry and the results showed that the predominant phase of the lead dioxide anode is β-PbO2. The decolorization and mineralization of dye RB 194 was investigated by UV–vis measurements and TOC analysis. The removal efficiency was studied as a function of several operation variables, such as current densities, initial dye concentration, initial pH values and chloride ions. It was found that the TiO2-NTs/Sb–SnO2/PbO2 electrode exhibited good decolorization and mineralization capability of RB 194 in neutral conditions at a current density of 150mA/cm2, with an initial dye concentration of 30mg/L. On the basis of the reaction products identified, a possible degradation pathway for the anodic oxidation of non-biodegradable organic dye RB 194 in aqueous solution is proposed.

Electrochemical oxidation of aqueous phenol at low concentration using Ti/BDD electrode

The high quality boron-doped diamond (BDD) film electrodes deposited on titanium (Ti) substrate have been prepared by a microwave plasma-assisted chemical vapor deposition (MP-CVD) method. The products consist of high quality dense grains characterized by Raman spectroscopy and scanning electron microscopy (SEM) employed. The BDD electrodes have wide electrochemical window (approximate 4.0V) and low background current (near zero) and the oxidation peak of phenol appears before the discharge of water, examined by cyclic voltammetry and linear sweep voltammetry. Compared with the fluorine-doped lead dioxide anodes (Ti/F-PbO2), the Ti/BDD anodes showed higher current efficiency and lower power consumption with degradation of low concentration phenol. The experimental results demonstrated that the BDD electrode on the Ti substrate possesses the excellent electrocatalytic activity in dilute solution.

Electrocatalytic Degradation of Cellulose Using Lead Dioxide Anode

A novel method of cellulose degradation is investigated in this paper. In this work, a three-electrode system, which contains a Pb/PbO2 anode, two copper cathodes and a reference saturated calomel electrode (SCE), is applied to electrocatalytic degradation of cellulose. The composition of the products in filtrate is characterized by phenol-sulfuric acid method, NMR and GC-MS. In addition, the solid sample is analyzed via Ubbelohde capillary viscometer and FT-IR spectra. The results suggest that it is effective to convert cellulose to soluble sugar, 5-hydroxymethylfurfural (5-HMF) and other products by electrocatalytic method. The reaction mechanism of cellulose degradation is also discussed.

Electrochemical degradation of some organic dyes by electrochemical oxidation on a Pb/PbO2 electrode

This work investigated the electrocatalytic degradation of three types of textile dyes by electrochemical oxidation on lead dioxide anode. The influence of pH, current density, time of electrolysis, temperature, the conductive salt concentration and the initial dye concentrations were critically examined. The results of these influences are expressed in terms of the remaining organic compounds concentrations (color removal) and Chemical Oxygen Demand (COD removal). Also, both of the current efficiency and power consumption values are calculated. In this manuscript we report that, the highest electrocatalytic activity was achieved in the presence of NaCl (3 g/l), 30 mA/cm2, pH of 3 and temperature of 30 °C. The highest electroactivity could be attributed to indirect oxidation of the investigated dyes by the electrogenerated hypochlorite ions formed from the chloride oxidation. In addition, contribution from direct oxidation could also be possible via reaction of these dyes with the electrogenerated hydroxyl radicals adsorbed on the lead dioxide surface.

Lead dioxide film sonoelectrodeposition in acidic media: Preparation and performance of stable practical anodes

Practical lead dioxide anodes have been obtained by electrodeposition on glassy carbon and titanium substrates in the presence and in the absence of an ultrasound field. The films obtained by mechanical agitation on glassy carbon are strongly improved when the electrodeposition process is carried out with the ultrasound field, providing adherent deposits free from nodules and stress, but with pores appearing occasionally. These enhanced properties were not achieved by mechanical conditions, even when optimization of temperature, current density, additives and geometrical aspects was attempted. The best practical anodes were obtained by sonoelectrodeposition using specially treated titanium as substrate, providing comparable behavior to commercial electrodes.

Investigation on electrochemical properties of cerium doped lead dioxide anode and application for elimination of nitrophenol

The present work focused on the investigation of electrochemical properties of cerium doped lead dioxide anode, i.e. Ti/Ce–PbO 2. SEM, AFM, XRD and XPS were used to characterize the morphology, crystal structure and elemental states of the modified anode. Electrochemical impedance spectroscopy (EIS) was also utilized to study the electrochemical property of Ti/Ce–PbO 2. The electrochemical activity of the Ti/Ce–PbO 2 anode was investigated by means of bulk electrolysis and compared with that of a PbO 2 anode. The accelerated life test and oxidants determination were also conducted. The results indicated that the incorporation of cerium improved the electrocatalytic activity and stability of PbO 2 anode. The service life of Ti/Ce–PbO 2 electrode was much longer than that of traditional lead dioxide electrode. The electrochemical activity obtained from degradation of o-nitrophenol ( o-NP) outperformed the traditional lead dioxide electrode as well. The Ti/Ce–PbO 2 electrode is considered a promising anode for the treatment of organic pollutants.

Electrochemical process for the treatment of landfill leachate

In this paper, the anodic oxidation of a real leachate from an old municipal solid waste landfill has been studied using an electrolytic flow cell equipped with a lead dioxide (PbO2) anode and stainless steel as the cathode. The influence of several operation parameters such as (i) the applied current (from 0.5 to 3 A), (ii) liquid flow rate (from 50 to 420 L h−1), (iii) temperature (from 25 to 50 °C), and (iv) pH (from 3.5 to 8.2) on the COD removal rate, current efficiency, and energy consumption has been evaluated. The galvanostatic electrolyses always yielded COD values below the discharge limit (COD <160 mg L−1); the COD removal rate increased with rising applied current, solution pH, and temperature, whereas it remained almost unaffected by the recirculation flow rate. These results indicate that the organic compounds were mainly removed by their indirect oxidation by the active chlorine generated from chlorides oxidation. The specific energy consumption necessary to reduce the organic load to below the disposal limit was 90 kWh m−3.