High Oxygen Evolution Potential Research Articles

Preparation of nanosheet-based spherical Ti/SnO2-Sb electrode by in-situ hydrothermal method and its performance in the degradation of methylene blue

Electrocatalytic oxidation technology and dimensionally stable anodes are widely used in the field of organic dye wastewater treatment. Rational manipulation of microscopic morphology, surface chemistry, and electrode configuration on DSA is of prime importance to enhance its electrochemical performance in the electrocatalytic degradation of organic pollutants. Herein, a novel Ti/SnO2-Sb anode with a microsphere structure composed of nanosheet was prepared by the in-situ hydrothermal method. And this electrode was compared with a control sample prepared by the traditional thermal decomposition method in terms of microscopic morphology, chemical structure, and electrochemical performance in the degradation of methylene blue. Benefiting from the nanosheet structure, small grain size, and higher Sb2O5 content, the electrode prepared by the hydrothermal method had a higher Oxygen Evolution Potential (2.09V), a smaller impedance (8.61Ω), and a larger Electrochemical Active Surface Area. And its removal rate of methylene blue reached 100% while the total organic carbon content reduced by 39.20% within 60 min, which is significantly superior to that of traditional thermal decomposition electrodes. This study highlights that the electrode prepared by single-step hydrothermal process shows more excellent catalytic performance than that by the traditional thermal decomposition process and the hydrothermal method has bright application prospects in DSA for electrocatalytic oxidation.

Enhanced Mechanism of Electrochemical Oxidation of Antibiotic Norfloxacin using a Ti/SnO2-Sb2O3/α,β-Co-PbO2 Electrode

This study focused on the enhanced mechanism of electrochemical degradation of antibiotic norfloxacin (NOR) using a self-made Ti/SnO2-Sb2O3/α,β-Co-PbO2 electrode. The electrode characterization, reaction mechanism, degradation performance, and toxicity assessment were studied. In contrast to the conventional Ti/SnO2-Sb2O3/α,β-PbO2 electrode, our prepared Co-doped PbO2 electrode showed the characteristics of more compact surface, smaller crystal size, higher oxygen evolution potential (OEP) and an increased yield of ·OH concentration. The application of Co-doped PbO2 electrode for the electrochemical oxidation of NOR was systematically analyzed. The optimal operating parameters were found to be Na2SO4 concentration of 0.1 mol L−1, initial NOR concentration of 50 mg L−1, initial pH of 5 and current density of 20 mA cm−2. Under these conditions, NOR, chemical oxygen demand (COD) and total organic carbon (TOC) removals reached 85.29%, 43.65% and 41.89% after 60 min of electrolysis, respectively. Through the intermediates detected during the electrochemical treatment process, a reaction pathway involving decarboxylation, defluorination and piperazine ring-opening was proposed. Finally, the toxicity assessment of the treated NOR solution towards Vibrio fischeri rapidly fell to non-toxicity and even reached to negative values after 50 min of electrolysis, indicating that electrochemical oxidation of NOR is an effective approach to reduce its toxicity to environmental ecosystem.

Fabrication of In2O3 doped PbO2 anode and its application for electrochemical degradation of norfloxacin in aqueous solutions

To improve the electrochemical activity and stability of PbO2 electrode, In2O3 particles were doped into β-PbO2 active layer by composite electrodeposition technology. When the In2O3 concentration in electrodeposition solution was 2 mM, the In2O3-PbO2 electrode had larger specific surface area, tighter crystal structure, higher oxygen evolution potential (2.09 V vs. SCE), smaller charge transfer resistance (64.32 Ω/cm2), stronger ability to generate hydroxyl radicals (0.213 μM/min) and thereby the better electrocatalytic activity and stability. In electrochemical oxidation of norfloxacin (NOR), the NOR removal rate at the In2O3-PbO2 anode was 1.388 times faster than that at pristine PbO2 electrode. Additionally, the effects of current density, initial pH, initial NOR concentration and electrolyte concentration on NOR removal efficiency were investigated by the principle of single variable. With the increase of current density and the decrease of initial NOR concentration, the NOR removal efficiency increased significantly; the better degradation effect was obtained under pH 3 and Na2SO4 concentration of 0.2 M. Finally, the degradation mechanism of NOR was discussed and five possible degradation pathways were proposed.

Electrochemical decomposition of PPCPs on hydrophobic Ti/SnO2-Sb/La-PbO2 anodes: Relationship between surface hydrophobicity and decomposition performance

The global detection and potential harm of pharmaceuticals and personal care products (PPCPs) call for the effective decomposition technology. In this study, the modified β-PbO2 anodes with different hydrophobicity (Ti/SnO2-Sb/La-PbO2, Ti/SnO2-Sb/La-PbO2-PTFE and Ti/SnO2-Sb/La-PbO2-PVDF) were prepared to decompose aqueous PPCPs, i.e. isoniazid, methotrexate, carbamazepine, sulfamethoxazole and ibuprofen. PTFE and PVDF modification improved the physical property, electrochemical property, stability and safety of β-PbO2 electrode. Moreover, Ti/SnO2-Sb/La-PbO2-PVDF had the highest oxygen evolution potential (1.95 V vs. SCE), the largest electroactive area (88.85 cm2), the highest HO• production rate (10.44 mM min−1 m−2) and the best degradation performance for all the five PPCPs. The hydrophobic surface increased the proportion of free HO•, resulting in higher radical utilization rate and better degradation performance. The excessive hydrophobicity could decrease the degradation performance of PPCPs with high log Kow due to the relatively large hydrophobic force zone. Furthermore, the hydrophobicity enhanced the mineralization (current) efficiency of isoniazid, and its electrochemical degradation mechanism on Ti/SnO2-Sb/La-PbO2-PVDF was thoroughly proposed. These results demonstrated that Ti/SnO2-Sb/La-PbO2-PVDF anode exhibited a good application prospect in treating wastewater containing PPCPs.

Ti/CoTiO3-TiO2 for Efficient Degradation of Refractory Organic Dyes: Synthesis, Characterization, and Electrocatalytic Properties

A Ti/CoTiO3-TiO2 catalyst electrode was successfully prepared by a one-step impregnation pyrolysis method and systematically investigated through scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The electrochemical characterization results containing cyclic voltammetry, electrochemical impedance spectroscopy, and linear sweep voltammetry further indicate that the as-prepared Ti/CoTiO3-TiO2 has higher oxygen evolution potential, lower resistance, higher electrochemical active surface area, and a longer lifetime than that of the pristine Ti/TiO2. A variety of dyes were selected as the target degraded pollutants for evaluating the electrocatalytic performance of Ti/CoTiO3-TiO2. Compared with those of the Ti/TiO2 and other counterparts, the Ti/CoTiO3-TiO2 shows significantly higher degradation efficiency, up to 98.5% under optimal conditions. Moreover, the Ti/CoTiO3-TiO2 displays superior stability and reusability. The higher electrochemical activity of Ti/CoTiO3-TiO2 than Ti/TiO2 may be the main reason for electrocatalytic performance enhancement, and the numerous ·OH and O2 − radicals generated on the anode surface may be the primary active species for dyes degradation. In addition, the possible degradation mechanism was inferred by analyzing the measured intermediates. Consequently, this work offers a strategy via constructing titanate composites to enhance the electrocatalytic degradation performance for the refractory organic pollutants.

Preparation and performance of highly active and long-life mesopore Ti/SnO2–Sb electrodes for electrochemical degradation of phenol

In this study, a new method for the controlled preparation of mesoporous Ti/Ce–Mn/meso–SnO2–Sb electrodes was established by introducing a Ce–Mn composite interlayer with Pluronic F127 (EO106PO70EO106) as the pore-forming agent and using a stepwise electrodeposition method. The results of the experiment indicated that the mesoporous electrodes prepared using electrodeposition had a larger specific surface area (68.37 m2 g−1), a high oxygen evolution potential (2.16 V) and good mechanical properties. The degradation extent of phenol increased from 72.34% to 91.83% and the Chemical Oxygen Demand (COD) removal extent increased from 59.31% to 81.25% within 120 min. The service life of the Ti/Ce–Mn/meso–SnO2–Sb electrode was improved nearly 15-fold compared with the conventional Ti/SnO2–Sb electrode produced using the brushing method. The results showed that the stepwise electrodeposition method can refine the coating grains. The introduction of the Ce–Mn intermediate layer increased the bonding between the coating and the Ti substrate. The mesoporous structure provided more in situ catalytic active sites and promoted the generation of •OH and catalytic oxidation of phenol. This method provides technical support and a theoretical basis for achieving controllable preparation and industrial application of high-performance titanium-based tin electrodes.

Embedding wasted hairs in Ti/PbO2 anode for efficient and sustainable electrochemical oxidation of organic wastewater

Despite of the hazardous risk of Pb2+ leakage, lead dioxide has been attributed as a quasi-ideal anode material with high oxygen evolution potential, excellent conductivity, good stability and low cost in electrochemical oxidation wastewater treatment technique. In this study, a novel Ti/PbO2 anode was fabricated by embedding raw materials that are readily and cheaply available, i.e., hairs. The structure-activity relationship of the new electrode was firstly revealed by material and electrochemical characterizations. Then different levels of pollutants (azo dye, phenol and maleic acid) were used to investigate the electrochemical oxidation performance of the new electrode. Finally, the accelerated electrode lifetime and Pb2+ leakage tests were carried out. Results showed that the embedded hairs changed the preferential crystallographic orientation of PbO2 and decreased the grain size. Hairs introduced additional roughness and active sites, and decreased the electrode impedance, especially under 5 mg/cm2 of embedding amount. The removal efficiencies of different target pollutants were enhanced more or less by embedding appropriate amount of hairs, depending on the current density, but loading excessive hairs had a negative effect. The accumulation of intermediate products during phenol degradation was also changed by the hairs. The new electrode could undergo ∼550 h of harsh electrolysis. It is also relieved that the Pb2+ leakage was found to be suppressed during this long-term electrolysis process.

Evaluation of diclofenac degradation effect in “active” and “non-active” anodes: A new consideration about mineralization inclination

This work investigates the electrochemical oxidation (EO) of diclofenac (DCF) in water with Ti/Ti4O7, Ti/Ru–Ir, Ti/Sb–SnO2 and Ti/PbO2 electrodes. Scanning electron microscope and X-ray diffraction results suggest that Ti/Ti4O7 has porous stacked surface morphology and Ti/Sb–SnO2 possesses the smallest grain size. Linear sweep voltammetry test results indicate that PbO2 has the highest oxygen evolution potential, while Ti/Ti4O7 and Ti/Ru–Ir show better oxygen evolution activity. DCF degradation results reveal that PbO2 possessed the highest DCF removal (RDCF = 99.2%) and chemical oxygen demand (COD) removal (RCOD = 97.0%), the fastest COD degradation rate (k = 0.0275 min−1, R2 = 0.964), the lowest specific energy consumption (ECDCF = 1.81 kWh.g DCF−1, ECTOC = 6.90 kWh.g TOC−1). The toxicity variation of DCF during EO process on PbO2 is rise first and then to fall. Considering the differences of the four electrodes in residual, conversion and mineralization aspects, mineralization selectivity (MS) was proposed to estimate the mineralization inclination of electrodes during EO process, and PbO2 displays the strongest mineralization inclination (MS = 0.594). In addition, the possible degradation pathway of DCF on PbO2 electrode indicates a composite behavior of conversion and mineralization. All of them above indicate the promising application potential of PbO2 in lower concentration pharmaceuticals and personal care products wastewater treatment. Moreover, MS could be employed as a supplementary index to assess the different inclinations of this composite behavior on various electrodes used for electrochemical treatment of organics in later studies.

Enhancing the electrochemical activity and stability of Sb-SnO2 based electrodes by the introduction of nickel oxide

Antimony doped tin(IV) oxide (Sb-SnO2) based electrodes are attractive candidates due to their high electrochemical activity but remain a grand challenge for stability. Therefore, there is an urgent need to develop approaches available for stabilizing electrode materials against deactivation during electrochemical oxidation process (EOP). Here we report a viable approach to extend the electrode lifetime without sacrificing its electrochemical activity. Electrochemical measurements showed that the introduction of NiO results in an increased voltammetric charge (q*) and excellent electrochemical activity towards methylene blue (MB) oxidation. TiO2-NiO@Sb-SnO2 electrode exhibited an improved electrochemical stability in comparison with TiO2@Sb-SnO2 counterpart. These merits coupled with high oxygen evolution potential (OEP) provide a foundation for a toolkit to design new electrodes with high electrochemical activity and stability.

Electrochemical investigation of different electrodes toward the removal of non-basic nitrogen compound from model diesel fuel

• Electrochemical denitrification of non-basic nitrogen compound in model diesel fuel. • Electrooxidative investigation of pyrrole in divided cell using several electrodes. • Electrooxidation and electropolymerization as two dominated proposed mechanism. • Carbon-based electrodes have better tendency towards oxidation than polymerization. • CP electrode could attain highest denitrification and current efficiency. In this study, the electrochemical removal of pyrrole as a non-basic nitrogen compound in diesel model fuel was investigated using platinum (Pt), graphite (Gr), carbon paper (CP), lead/lead dioxide (Pb/PbO 2 ), and tin/tin dioxide (Sn/SnO 2 ) working electrodes in a divided cell. Electrochemical analysis such as cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectrometry, and Tafel test was utilized to determine different behavior of electrodes. According to gas chromatography results, pyrrole removal efficiency at a constant current density of 17 mA cm −2 during 6 h was in the range of 83%–100% for Sn/SnO 2 and CP electrodes, respectively. The denitrification reaction using CP, Gr, and Sn/SnO2 electrodes was diffusion-controlled regarding data extracted from cyclic voltammetry at various scan rates. However, the adsorption mechanism was dominated by Pt and Pb/PbO 2 electrodes. Tafel analysis demonstrated that the electrocatalytic activity of electrodes is as follows: Pt > CP > Gr > Pb/PbO 2 > Sn/SnO 2 . Besides, the formation of polypyrrole and low oxygen evolution potential diminished Pt pyrrole removal efficiency. Carbon-based electrodes with pyrrole oxidation potential near Pt electrode and higher oxygen evolution potential can be utilized as efficient and cost-effective electrodes in the denitrification process.

Environmentally Friendly Fabrication of Ti/RuO2-IrO2-SnO2-Sb2O5 Anode with In Situ Incorporation of Reduced TiO2 Interlayer

The intensive use of chemical reagents in the pretreatment of Ti substrate and shorter electrode life constrict the wider application of the dimensionally stable anode (DSA). In this study, a simple method was developed to thermally pretreat the Ti substrate in the atmosphere of H2 and N2 (molar ratio 1:5) without chemicals consumption and wastewater discharge. It was found that the reduced TiO2 interlayer could be favorably created at temperature of 750 °C. This rendered Ti/reduced TiO2/RuO2-IrO2-SnO2-Sb2O5 anode with better stability and higher electrocatalytic activity. The accelerated lifetime for Ti/reduced TiO2/RuO2-IrO2-SnO2-Sb2O5 electrode was 65 h with the optimum catalyst loading amount (2.6 ± 0.05 mg cm−2), while it was only 50 h for traditional Ti/RuO2-IrO2-SnO2-Sb2O5 electrode. As compared with the counterparts, Ti/reduced TiO2/RuO2-IrO2-SnO2-Sb2O5 with higher oxygen evolution potential (1.42 V/SCE) and lower chlorine evolution potential (1.12 V/SCE), suggesting higher electro-catalytic activity toward reactive oxidative species formation. The deactivation test indicates that the anode deactivation mainly proceeded via the dissolution of the catalyst layer and then formation of insulated TiO2 on the substrate. Generally, an environmentally friendly Ti substrate pretreatment method was developed and demonstrated promising for upgrading DSA fabrication process in industrial application.

Application of a fluidized three-dimensional electrochemical reactor with Ti/SnO2–Sb/β-PbO2 anode and granular activated carbon particles for degradation and mineralization of 2,4-dichlorophenol: Process optimization and degradation pathway

A three-dimensional electrochemical reactor with Ti/SnO2–Sb/β-PbO2 anode and granular activated carbon (3DER-GAC) particle electrodes were used for degradation of 2,4-dichlorophenol (2,4-DCP). Process modeling and optimization were performed using an orthogonal central composite design (OCCD) and genetic algorithm (GA), respectively. Ti/SnO2–Sb/β-PbO2 anode was prepared by electrochemical deposition method and then its properties were studied by FESEM, EDX, XRD, Linear sweep voltammetry and accelerated lifetime test techniques. The results showed that lead oxide was precipitated as highly compact pyramidal clusters in the form of β-PbO2 on the electrode surface. In addition, the prepared anode had high stability (170 h) and oxygen evolution potential (2.32 V). A robust quadratic model (p-value < 0.0001 and R2 > 0.99) was developed to predict the 2,4-DCP removal efficiency in the 3DER-GAC system. Under optimal conditions (pH = 4.98, Na2SO4 concentration = 0.07 M, current density = 35 mA cm−2, GAC amount = 25 g and reaction time = 50 min), the removal efficiency of 2,4-DCP in the 3DER-GAC system and the separate electrochemical degradation process (without GAC particle electrode) were 99.8 and 71%, respectively. At a reaction time of 80 min, the TOC removal efficiencies in the 3DER-GAC and the separate electrochemical degradation system were 100 and 57.5%, respectively. Accordingly, the energy consumed in these two systems was calculated to be 0.81 and 1.57 kWh g−1 TOC, respectively. Based on the results of LC-MS analysis, possible degradation pathways of 2,4-DCP were proposed. Trimerization and ring opening reactions were the two dominant mechanisms in 2,4-DCP degradation.

Electrocatalytic degradation of diuron herbicide using three-dimensional carbon felt/β-PbO2 anode as a highly porous electrode: Influencing factors and degradation mechanisms

Traditional planar PbO2 anodes have been used extensively for the electrocatalytic degradation process. However, by using porous PbO2 anodes that have a three-dimensional architecture, the efficiency of the process can be significantly upgraded. In the current study, carbon felt (CF) with a highly porous structure and a conventional planar graphite sheet (G) were used as electrode substrate for PbO2 anodes. Both CF/β-PbO2 and G/β-PbO2 anodes were prepared by the anodic deposition method. The main properties of the electrodes were characterized by XRD, EDX-mapping, FESEM, and BET-BJH techniques. The electrocatalytic degradation of diuron using three-dimensional porous CF/β-PbO2 anode was modeled and optimized by a rotatable central composite design. After optimizing the process, the ability of porous CF/β-PbO2 and planar G/β-PbO2 anodes to degrade and mineralize diuron was compared. The electrocatalytic degradation of the diuron was well described by a quadratic model (R2 > 0.99). Under optimal conditions, the kinetics of diuron removal using CF/β-PbO2 anode was 3 times faster than the G/β-PbO2 anode. The energy consumed for the complete mineralization of diuron using CF/β-PbO2 anode was 2077 kWh kg−1 TOC. However, the G/β-PbO2 anode removed only 65% of the TOC by consuming 54% more energy. The CF/β-PbO2 had more stability (115 vs. 91 h), larger surface area (1.6287 vs. 0.8565 m2 g−1), and higher oxygen evolution potential (1.89 vs. 1.84 V) compared to the G/β-PbO2. In the proposed pathways for diuron degradation, the aromatic ring and groups of carbonyl, dimethyl urea, and amide were the main targets for HO• radical attacks.

Electrochemical degradation of tris(2-chloroethyl) phosphate by metal-oxide-coated Ti anodes: Kinetics, toxicity and mechanism

The current study presents a comprehensive and novel attempt to degrade aqueous tri(2-chloroethyl) phosphate (TCEP) by metal-oxide-coated Ti anodes for the first time. Six metal-oxide-coated Ti electrodes (Ti/SnO2-Sb, Ti/SnO2-Sb/PbO2, Ti/SnO2-Sb/La-PbO2, Ti/SnO2-Sb/Ce-PbO2, Ti/SnO2-Sb/Ga-PbO2 and Ti/SnO2-Sb/Zr-PbO2) were prepared and characterized. Ti/SnO2-Sb/La-PbO2 showed the highest pseudo-first-order reaction rate constant (2.1 × 10−2 min−1) and lowest energy consumption (21.35 Wh L−1) in the degradation of 1 mg L−1 TCEP at 10 mA cm−2, mainly because of its highest oxygen evolution potential and OH production. Higher current density and neutral condition favored TCEP degradation, while the presence of Cl− or NO3− could suppress the degradation. In the electrochemical degradation of 10 mg L−1 TCEP, mineralization percentage of 48.0% (mineralization current efficiency of 0.30%) and PO43− release percentage of 72.7% were achieved at 150 min. By the attack of OH on the CO and CCl bonds in TCEP molecular structure, products of chloroethanol, Cl− and PO43− were released, with the major electrocatalytic degradation pathways of dechlorination and hydroxylation. Based on the results of flow cytometry, the relative toxicity to Escherichia coli effectively decreased to 4.93% in TCEP degradation. Compared with the UV-AOPs, electrochemical oxidation process is proved to be feasible and effective for mineralization and detoxification of TCEP in water.

A facile electroless preparation of Cu, Sn and Sb oxides coated Ti electrode for electrocatalytic degradation of organic pollutants

Electrocatalytic degradation of organic pollutants is an encouraging technology for wastewater treatment. To achieve practical application, electrode plate with cost effective fabrication, high catalytic efficiency and long service life is urgently required. This work prepared a CuO-SnO2-SbOX electrode on Ti substrate, which is achieved by ultrasonic assisted deposition of Cu layer, followed by electroless deposition of SnSb layer and finalized by calcination at 500 °C. The obtained electrode (Ti/CuO-SnO2–SbOX) exhibited high catalytic degradation activity and a high oxygen evolution potential (OEP) of 2.13 V, which is 0.4 V greater than that of the widely recognized Ti/SnO2–SbOX electrode. The oxygen evolution reaction (OER) models of active oxygen intermediate adsorption was optimized by density functional theory (DFT) calculations. The results revealed that (1) the ΔG of the OER rate-determining step was raised to 2.30 eV after Cu doping on 101 plane; (2) binding energies of the optimized surface with reactive oxygen species (ROS) were substantially decreased. Furthermore, the as-prepared electrode has a high yield of hydroxyl radical generation as evidenced by terephthalic acid detection. The potential for hydroxyl radical generation was measured to be 1.8 V at pH = 12 and 2.6 V at pH = 2.The catalytic degradation rate of methylene blue (MB) follows pseudo first order reaction kinetics, and the reaction constant K value reached 0.02964 -k/min−1, twice as much as that obtained from electrodeposition electrode (Ti/Cu/SnO2–SbOX). A degradation rate of 94.6% was achieved for MB in 100 min in the first run, and the value remained over 85% in the subsequent 10 runs. At the same conditions, the degradation rate of p-nitrophenol was over 90% in 100 min and complete mineralization was achieved in 4 h.

Insight on the Electrochemical Degradation of Cartap in Padan 95SP: Kinetic and Mechanism

This study investigated the electrochemical degradation of Cartap (in Padan 95 SP) at BDD electrode. BDD shows high electrochemical activity, high stability as indicated in their CVs and LSV although not really high oxygen evolution potential, which depends under experimental conditions. This study confirms that the degradation of Cartap was undergone via both direct and indirect oxidations. The influence of current density on Cartap degradation was investigated in detail, indicating the dependence of Cartap removal versus current density as represented in a quadratic function. Other important parameters were figured out: half-life t 1/2 = (315 min – 108 min) depending on the applied current density ( j from 5 mA·cm -2 to 20 mA·cm -2 ). Besides, we explored a calculation method for assessing the contribution of radical species as well as their production mechanism.

An α-Fe2O3/Circulating Fluidized Bed Fly Ash Based Geopolymer Composite Anode for Electrocatalytic Degradation of Indigo Carmine Dye Wastewater

Geopolymers have been developed to various catalysts due to their advantages. However, low conductivity restricts their application in the electrocatalysis field. In this study, an α-Fe2O3/circulating fluidized bed fly ash based geopolymer (CFAG) composite anode was fabricated using a facile dip-coating method by loading α-Fe2O3 in the matrix of CFAG. The effects of α-Fe2O3 content on the composition, surface morphology and electrochemical performance of α-Fe2O3/CFAG composite anode were investigated. The X-ray diffraction (XRD) and scanning electron microscope (SEM) results demonstrated that α-Fe2O3 was successfully inlaid with the surface of amorphous CFAG matrix. The electrochemical measurements indicated that α-Fe2O3/CFAG composite anode had higher oxygen evolution potential, greater electrochemical activity area, and smaller electrochemical impedance than CFAG. The as-prepared composite anode was applied for electrocatalytic degradation of indigo carmine dye wastewater. It was discovered that the highest degradation efficiency over 10α-Fe2O3/CFAG reached up 92.6%, and the degradation of indigo carmine followed pseudo-first-order kinetics. Furthermore, 10α-Fe2O3/ CFAG composite anode presented excellent stability after five cycles. The active hydroxyl radical was generated over the α-Fe2O3/CFAG composite anode, which acted as strong oxidizing agents in the electrocatalytic degradation process.

Pr-Si co-doped IrOx as promoted anode for refractory SDZ degradation

Electrochemical oxidation technology has been used in treating bio-refractory organic effluent. However, the energy consumption is subject to the high oxygen evolution potential (OEP) of the traditional electrode. Doped Ir-contained oxides electrode is capable of degrading pollutants efficiently at low energy consumption. In this study, a facile (Ir 0.4 Pr 0.4 Si 0.2 )O x electrode was prepared using the thermal decomposition method, which exhibits a larger electrochemical surface area (ECSA, 287.71 cm 2 ) and tunnel structures caused by Pr and Si’s leaching. The (Ir 0.4 Pr 0.4 Si 0.2 )O x electrode was applied to degrade sulfadiazine (SDZ). The parameters of the initial concentration of SDZ, electrolyte concentration, pH, and the applied voltage on SDZ removal were investigated. The optimal condition was explored, and the SDZ degradation efficiency reached 100% within 2 h. We attribute the excellent degradation performance to the presence of tunnel structures on the electrode, which promotes the generation of ·O 2 − and ·OH. An indirect electrochemical oxidation mechanism is proposed according to the identification of the intermediate through the LC-MS. The novel electrode achieved in this work is promising to treat acid SDZ wastewater in the electrochemical system.

High Efficiency Electrochemical Degradation of Phenol Using a Ti/PbO2-Bi-PTh Composite Electrode

A novel Ti/PbO2-Bi-PTh composite electrode was successfully prepared by electrodeposition and applied in electrochemical degradation of phenol. The Ti/PbO2-Bi-PTh electrode was characterized by XRD, SEM, AFM, LSV, CV and EIS. Results showd that the electrode has a fine and compact surface structure, higher oxygen evolution potential (OEP, 2.42 V) and low charge transfer resistance (51.00 Ω). The electrode also exhibited excellent electrochemical oxidation activity on the degradation of phenol (1000 mg l−1) with degradation efficiency of 100% and TOC removal rate of 93.58% achieved in 60 min and 180 min, respectively. In addition, possible mechanism of phenol degradation on the electrode was proposed by analyzing the intermediate products with GC-MS. Noticeably, the Ti/PbO2-Bi-PTh electrode displayed excellent stability and high electrocatalytic performance after 10 cycles, indicating its promising application in the phenolic wastewater treatment.

Electrochemical oxidation of aniline using Ti/RuO2-SnO2 and Ti/RuO2-IrO2 as anode

Electrocatalytic properties of anode and the electrolyte composition are important parameters influence the degradation efficiency for aniline wastewater. Ti/RuO2-SnO2 and Ti/RuO2-IrO2 have been fabricated using thermal decomposition method and experiments in electrolyte containing 0.05 M Na2SO4, 0.05 M NaCl and 0.05 M Na2SO4+0.005 M FeSO4 at different current density were conducted to study the influence on aniline degradation. Linear sweep voltammetry (LSV) showed that Ti/RuO2-SnO2 had higher oxygen evolution potential and degrade aniline through electrochemical transformation and electrochemical combustion while Ti/RuO2-IrO2 degrade aniline mainly through electrochemical transformation. The study showed that Ti/RuO2-SnO2 had higher electrocatalytic activity towards the degradation of aniline than Ti/RuO2-IrO2 anode in 0.05 M Na2SO4 and in 0.05 M NaCl electrolyte. The maximum TOC removal efficiency for Ti/RuO2-SnO2 was 64.2% at 40 mA cm−2 in Na2SO4 electrolyte while the average MCE was 1.6% and the average ECTOC was 1.51 kWh (g TOC)−1. On the contrary, the maximum TOC removal efficiency for Ti/RuO2-IrO2 was 63.1% at 40 mA cm−2 in NaCl electrolyte while the average MCE was 1.6% and the average ECTOC was 1.95 kWh (g TOC)−1. The presence of Fe2+ in Na2SO4 electrolyte would decrease the TOC removal efficiency except at low current density (20 mA cm−2) for Ti/RuO2-SnO2. These results indicated that Ti/RuO2-SnO2 and Ti/RuO2-IrO2 anode were suitable in Na2SO4 and NaCl electrolyte, respectively, while the presence of Fe2+ would inhibit aniline degradation.