Electrochemical degradation of phenol using electrodes of Ti/RuO(2)-Pt and Ti/IrO(2)-Pt

Electrochemical degradation of phenol was evaluated at two typical anodes, Ti/RuO(2)-Pt and Ti/IrO(2)-Pt, for being a treatment method in toxic aromatic compounds. The influences of current density, dosage of NaCl, initial phenol concentration on electrochemical phenol degradation were investigated. It was found that Ti/RuO(2)-Pt anode had a higher oxygen evolution potential than Ti/IrO(2)-Pt anode, which will increase the current efficiency for electrochemical degradation, and the instantaneous current efficiency (ICE) was relatively higher at the initial time during phenol electrolysis. HOCl formed during electrolysis would play an important role on the oxidation of phenol. For the Ti/RuO(2)-Pt anode, phenol concentration decreased from around 8mg/L to zero after 30min of electrolysis with 0.3g/L NaCl as supporting electrolyte at the current density of 10mA/cm(2). Although phenol could be completely electrochemical degraded at both Ti/RuO(2)-Pt and Ti/IrO(2)-Pt anodes, phenol degradation was slower at the Ti/IrO(2)-Pt anode than at the Ti/RuO(2)-Pt anode due to the fact that passivation was to be found at the Ti/IrO(2)-Pt anode.     

Ammonia removal in electrochemical oxidation: mechanism and pseudo-kinetics

This paper investigated the mechanism and pseudo-kinetics for removal of ammonia by electrochemical oxidation with RuO(2)/Ti anode using batch tests. The results show that the ammonia oxidation rates resulted from direct oxidation at electrode-liquid interfaces of the anode by stepwise dehydrogenation, and from indirect oxidation by hydroxyl radicals were so slow that their contribution to ammonia removal was negligible under the condition with Cl(-). The oxidation rates of ammonia ranged from 1.0 to 12.3 mg N L(-1)h(-1) and efficiency reached nearly 100%, primarily due to the indirect oxidation of HOCl, and followed pseudo zero-order kinetics in electrochemical oxidation with Cl(-). About 88% ammonia was removed from the solution. The removed one was subsequently found in the form of N(2) in the produced gas. The rate at which Cl(-) lost electrons at the anode was a major factor in the overall ammonia oxidation. Current density and Cl(-) concentration affected the constant of the pseudo zero-order kinetics, expressed by k=0.0024[Cl(-)]xj. The ammonia was reduced to less than 0.5 mg N L(-1) after 2h of electrochemical oxidation for the effluent from aerobic or anaerobic reactors which treated municipal wastewater. This result was in line with the strict discharge requirements.     

Comparative study on the catalytic electrooxidative abilities of RuO(x)-PdO-TiO(2)/Ti and RuO(x)-PdO/Ti anode

Comparative study of the catalytic electrooxidative abilities of RuO(x)-PdO/Ti and RuO(x)-PdO-TiO(2)/Ti were conducted using Active Orange 5R solution as simulated wastewater. RuO(x)-PdO-TiO(2)/Ti anode possesses higher catalytic oxidation ability, as compared to RuO(x)-PdO/Ti, in both direct oxidation and indirect oxidation processes. RuO(x)-PdO-TiO(2)/Ti could provide a discoloration rate of 98.14% within 30 min, while the COD removal could reach 51.43% in 120 min. It was indicated that higher electrooxidation ability could be achieved at RuO(x)-PdO-TiO(2)/Ti anode, which exhibited lower chlorine evolution potential and higher oxygen evolution potential probably resulted from the higher oxidation states of Ru and Pd.     

有色金属电积用钛基氧化物涂层阳极的研究进展

综述了国内外钛基氧化物涂层阳极的研究进展及应用,包括有色金属电积用钛基贱金属氧化物涂层和贵金属氧化物涂层,其中,钛基贱金属氧化物涂层详细阐述了钛基Pb系氧化物涂层、钛基Co系氧化物涂层、钛基Mn系氧化物涂层以及钛基Sn系氧化物涂层电极;钛基贵金属氧化物涂层重点阐述了Ti/Ta_2O_5-IrO_2涂层和Ti/Ru O_2-TiO_2涂层电极。评述了多元化钛基涂层的性能、各种涂层的优势与不足。     

涂层成分对IrO2（5）TiO2（60）Co3O4（x）RuO2（35—x）／Ti阳极材料析氯…

用电化学和Ｘ射线衍射方法研究了氧化物涂层成分热分解法制备的ＩｒＯ２（５）ＴｉＯ２（６０）Ｃｏ３Ｏ４（ｘ）ＲｕＯ２（３５－ｘ）／Ｔｉ阳极材料析氯速率的影响．ｘ值为０－１３ｍ／ｏ时，氧化物涂层为单相金红石型固溶体，阳极析氯速率随ｘ值增加，ｘ值大于１３ｍ／ｏ时，涂层中出现尖晶石Ｃｏ３Ｏ４第二相，析氯速率随ｘ值下降。     

Electrochemical oxidation of a textile dye wastewater using a Pt/Ti electrode

Textile dye wastewater (TDW) from a reactive azo dyeing process was treated by an electrochemical oxidation method using Ti/Pt as anode and stainless steel 304 as cathode. Due to the strong oxidizing potential of the chemicals produced (chlorine, oxygen, hydroxyl radicals and other oxidants) when the wastewater was passed through the electrolytic cell the organic pollutants were oxidized to carbon dioxide and water. A number of experiments were run in a batch, laboratory-scale, pilot-plant, and the results are reported here according to residence time and initial addition of HCl in raw wastewater. When of 2 ml of HCl 36% were added and after 18 min of electrolysis at 0.89 A/cm(2), chemical oxygen demand (COD) was reduced by 86%, biochemical oxygen demand (BOD(5)) was reduced by 71%, ADMI color units were reduced by 100%, and TKN was reduced by 35%. The biodegradability of the wastewater was improved because the COD/BOD ratio decreased from 2.16 to 1.52. At the same time the efficiency of the electrode was about 170 g h(-1) A(-1) m(-2). and the mean energy consumption was 21 kW h/kg of COD. These results indicate that this electrolytic method could be used for effective TDW oxidation or as a feasible detoxification and color removal pretreatment stage for biological post treatment.     

混合氧化物涂层钛基阳极的性能及其电子防腐蚀

辅助阳极是电子防腐蚀系统的关键部件之一,为提高其性能及寿命,利用热分解法制备了Ru-Ir-Sn-Ti混合氧化物涂层钛基阳极,用SEM,XRD,动电位极化曲线、强化电解寿命试验和热水器内胆电子防腐蚀试验考察了不同Sn含量的混合氧化物涂层钛电极的性能。结果表明:Ru-Ir-Sn-Ti混合氧化物涂层覆盖良好,呈均匀龟裂状;添加适量的Sn能提高涂层的电化学活性,含10%(摩尔分数)Sn涂层的电化学性能最优;含30%(摩尔分数)Sn涂层的强化电解寿命达58 h;混合氧化物涂层钛阳极在输入很小的电压时,能有效防止水下搪瓷碳钢在高硬度热水中的腐蚀,且能使阴极材料表面沉淀一层钙质层,增强了保护效果。     

Electrochemical treatment in relation to pH of domestic wastewater using Ti/Pt electrodes

This paper describes an electrochemical treatment of domestic wastewater (DW) using 0.8% (w/v) sodium chloride as electrolyte. In this technique, DW was passed through an electrolytic cell using Ti/Pt as anode and Stainless Steel 304 as cathode. Due to the strong oxidizing potential of the chemicals produced (chlorine, oxygen, hydroxyl radicals and other oxidants), the organic pollutants and nutrients (organic nitrogen, phosphorous) were wet oxidized to carbon dioxide, and nitrogen as well as phosphorous was precipitated as Ca(3)(PO(4))(2). Experiments were run in a continuous, laboratory-scale, pilot plant, at 40 degrees C and the efficiency of oxidation was studied in relation to pH. It was found that in alkaline conditions the electrolysis was more efficient. At pH 9, NaCl concentration 0.8% (w/v), current density 0.075 A/cm(2) and for 1h of electrolysis, COD was reduced by 89%, volatile suspended solids (VSS) by 90%, ammonia nitrogen by 82% and total phosphorous by 98%. The efficiency of electrolysis went up to 35 g COD(r)/(hm(2)A) and the energy consumption to 12.4 kWh/kg COD(r). It is concluded that the application of electrolytic oxidation of DW is more advantageous compared to conventional biological treatment especially for small works.     

涂层成分对IrO_2（5）TiO_2（60）Co_3O_4（x）RuO_2（35

用电化学和Ｘ射线衍射方法研究了氧化物涂层成分对热分解法制备的ＩｒＯ２（５）ＴｉＯ２（６０）Ｃｏ３Ｏ４（ｘ）ＲｕＯ２（３５—ｘ）／Ｔｉ阳极材料析氯速率的影响．ｘ值为０－１３ｍ／ｏ时，氧化物涂层为单相金红石型固溶体，阳极析氯速率随ｘ值增加，ｘ值大于１３ｍ／ｏ时，涂层中出现尖晶石Ｃｏ３Ｏ４第二相，析氯速率随ｘ值下降．     

Electrochemical treatment of Procion Black 5B using cylindrical flow reactor--a pilot plant study

The paper presents the results of an efficient electrochemical treatment of Procion Black 5B--a pilot plant study. Experiments were conducted at different current densities and selected electrolyte medium using Ti/RuO2 as anode, stainless-steel as cathode in a cylindrical flow reactor. By cyclic voltammetric analysis, the best condition for maximum redox reaction rate was found to be in NaCl medium. During the various stages of electrolysis, parameters such as COD, colour, FTIR, UV-vis spectra studies, energy consumption and mass transfer coefficient were computed and presented. The experimental results showed that the electrochemical oxidation process could effectively remove colour and the chemical oxygen demand (COD) from the synthetic dye effluent. The maximum COD reduction and colour removal efficiencies were 74.05% and 100%, respectively. Probable theory, reaction mechanism and modeling were proposed for the oxidation of dye effluent. The results obtained reveal the feasibilities of application of electrochemical treatment for the degradation of Procion Black 5B.     

The cooperative electrochemical oxidation of chlorophenols in anode-cathode compartments

By using a self-made carbon/polytetrafluoroethylene (C/PTFE) O2-fed as the cathode and Ti/IrO2/RuO2 as the anode, the degradation of three organic compounds (phenol, 4-chlorophenol, and 2,4-dichlorophenol) was investigated in the diaphragm (with terylene as diaphragm material) electrolysis device by electrochemical oxidation process. The result indicated that the concentration of hydrogen peroxide (H2O2) was 8.3 mg/L, and hydroxyl radical (HO) was determined in the cathodic compartment by electron spin resonance spectrum (ESR). The removal efficiency for organic compounds reached about 90% after 120 min, conforming to the sequence of phenol, 4-chlorophenol, and 2,4-dichlorophenol. And the dechlorination degree of 4-chlorophenol exceeded 90% after 80 min. For H2O2, HO existed in the catholyte and reduction dechlorination at the cathode, the mineralization of organics in the cathodic compartment was better than that in the anodic compartment. The degradation of organics was supposed to be cooperative oxidation by direct or indirect electrochemical oxidation at the anode and H2O2, HO produced by oxygen reduction at the cathode. High-performance liquid chromatography (HPLC) allowed identifying phenol as the dechlorination product of 4-chlorophenol in the cathodic compartment, and hydroquinone, 4-chlorocatechol, benzoquinone, maleic, fumaric, oxalic, and formic acids as the main oxidation intermediates in the cathodic and anodic compartments. A reaction scheme involving all these intermediates was proposed.     

多元中间过渡层钛基氧化锰电极的寿命及电化学性能

采用热分解法制备了不同中间层的钛基氧化锰电极,利用SEM、XPS和XRD方法对电极进行了表征,应用加速寿命试验方法测试了电极在60℃、1.0mol/L H2SO4溶液中的预期使用寿命,同时测定了酸性溶液中该类电极的动力学参数(a、b、i0),运用双位垒模型讨论了电极的电化学性能。结果表明,具有RuO2+SnO2+MnO2+Sb2O4固溶体中间层的钛基氧化锰电极在高电流密度下(4A/cm2)的寿命可高达58h,电化学动力学表明该电极在酸性溶液中的析氧活化能较低,a值较小,i0值较大,是酸性溶液中较好的析氧电极材料。     

Anodic destruction of 4-chlorophenol solution

The electrochemical oxidation of 4-chlorophenol solutions was studied using a dimensional stable anode (DSA), made of pure titanium sheet mesh coated with Ti/TiO(2) and RuO(2) film. An electrochemical cell with one working electrode and two counter-electrodes was designed. A gas collecting system to collect the electrolysis gaseous products was also designed. The influence of current density (6.51-21.58 mA/cm(2)), pH (2.0-12.6) and initial 4-chlorophenol concentration (25-100 mg/l) on the destruction was investigated. Complete elimination was successfully achieved within 2 h for most investigated conditions. Highest rates of elimination were achieved at a pH of 12.6.A new approach to calculate the current efficiency (CE) of the cell was proposed. The volumes of the gases produced at the anode and at the cathode were the basis for the new CE calculations. It was observed that the worst CE was approximately 20% and the best CE was approximately 89%. The most efficient pH was at 12.6 and the most efficient current density was at 11.39 mA/cm(2).     

Destination of organic pollutants during electrochemical oxidation of biologically-pretreated dye wastewater using boron-doped diamond anode

Electrochemical oxidation of biologically-pretreated dye wastewater was performed in a boron-doped diamond (BDD) anode system. After electrolysis of 12h, the COD was decreased from 532 to 99 mg L(-1) (<100 mg L(-1), the National Discharge Standard of China). More importantly, the destination of organic pollutants during electrochemical oxidation process was carefully investigated by molecular weight distribution measurement, resin fractionation, ultraviolet-visible spectroscopy, HPLC and GC-MS analysis, and toxicity test. As results, most organic pollutants were completely removed by electrochemical oxidation and the rest was primarily degraded to simpler compounds (e.g., carboxylic acids and short-chain alkanes) with less toxicity, which demonstrated that electrochemical oxidation of biologically-pretreated dye wastewater with BDD anode was very effective and safe. Especially, the performance of BDD anode system in degradation of large molecular organics such as humic substances makes it very promising in practical applications as an advanced treatment of biologically-pretreated wastewaters.     

Electrochemical treatment of paper mill wastewater using three-dimensional electrodes with Ti/Co/SnO2-Sb2O5 anode

The properties of the interlayer and outer layer of Ti/Co/SnO2-Sb2O5 electrode were studied, and the electrochemical behavior was examined as well. As a result of unsatisfactory treatment using Ti/Co/SnO2-Sb2O5 electrode, electrochemical disposal of paper mill wastewater employing three-dimensional electrodes, combining active carbon granules serving as packed bed particle electrodes, with Ti/Co/SnO2-Sb2O5 anode, was performed. The outcome demonstrates that efficient degradation was achieved. The residual dimensionless chemical oxygen demand (COD) concentration reached 0.137, and color removal 75% applying 167 mA cm(-2) current density at pH 11 and 15 g l(-1) NaCl. The instant current efficiency, energy cost, electrochemical oxidation index (EOI) and kinetic constant of the reaction were calculated. At the same time, the influence of pH and current density on COD abatement and decolorization was also investigated, respectively.     

Antibacterial Efficacy of Sacrifical Anode Thin Films Combining Silver with Platinum Group Elements within a Bacteria‐Containing Human Plasma Clot

Silver (Ag) dots arrays (64 and 400 dots per mm²) are fabricated on a continuous platinum (Pt), palladium (Pd), or iridium (Ir) thin film (sacrifical anode systems for Ag) and for comparison on titanium (Ti) film (non‐sacrifical anode system for Ag) by sputter deposition and photolithographic patterning. The samples are embedded within a tissue‐like plasma clot matrix containing Staphylococcus aureus (S. aureus), cultivated for 24 h. Bacterial growth is analyzed by fluorescence microscopy. Among platinum group sacrifical anode elements and a dense Ag sample, only the high Ag ion releasing Ag–Ir system is able to inhibit the bacterial growth within the adjacent plasma clot matrix. This study demonstrates that the antibacterial efficiency of Ag coatings is reduced under tissue‐like conditions. However, the new sacrificial anode based Ag–Ir system can overcome this limitation.

     

Electrochemical degradation of polycyclic aromatic hydrocarbons in creosote solution using ruthenium oxide on titanium expanded mesh anode

In this study, expanded titanium (Ti) covered with ruthenium oxide (RuO(2)) electrode was used to anodically oxidize polycyclic aromatic hydrocarbons (PAH) in creosote solution. Synthetic creosote-oily solution (COS) was prepared with distilled water and a commercial creosote solution in the presence of an amphoteric surfactant; Cocamidopropylhydroxysultaine (CAS). Electrolysis was carried out using a parallelepipedic electrolytic 1.5-L cell containing five anodes (Ti/RuO(2)) and five cathodes (stainless steel, 316 L) alternated in the electrode pack. The effects of initial pH, temperature, retention time, supporting electrolyte, current density and initial PAH concentration on the process performance were examined. Experimental results revealed that a current density of 9.23 mA cm(-2) was beneficial for PAH oxidation. The sum of PAH concentrations for 16 PAHs could be optimally diminished up to 80-82% while imposing a residence time in the electrolysis cell of 90 min. There was not a significant effect of the electrolyte (Na(2)SO(4)) concentration on oxidation efficiency in the investigated range of 500-4000 mg/L. However, an addition of 500 mg Na(2)SO(4)L(-1) was required to reduce the energy consumption and the treatment cost. Besides, there was no effect of initial PAH concentration on oxidation efficiency in the investigated range of 270-540 mg PAHL(-1). Alkaline media was not favourable for PAH oxidation, whereas high performance of PAH degradation could be recorded without initial pH adjustment (original pH around 6.0). Likewise, under optimal conditions, 84% of petroleum hydrocarbon (C(10)-C(50)) was removed, whereas removal yields of 69% and 62% have been measured for O&G and COD, respectively. Microtox and Daphnia biotests showed that electrochemical oxidation using Ti/RuO(2) could be efficiently used to reduce more than 90% of the COS toxicity.     

Electrochemical treatment of anionic surfactants in synthetic wastewater with three-dimensional electrodes

The electrochemical oxidation of anionic surfactants (sodium dodecyl benzene sulfonate, DBS) contained in simulated wastewater treated by three-dimensional electrode system with combined modified kaolin served as packed bed particle electrodes and Ti/Co/SnO(2)-Sb(2)O(3) anode was studied, the chemical oxygen demand (COD) removal of pollutants in the solutions was also investigated. The results showed that the three-dimensional electrodes in combined process could effectively decompose anionic surfactants. The COD removal efficiency can reach 86%, much higher than that of Ti/Co/SnO(2)-Sb(2)O(3) electrodes used singly or modified kaolin employed singly (graphite as anode and cathode) on the same condition of pH 3 and 38.1 mA/cm(2) current density. The current efficiency and kinetic constant were calculated and energy consumption was studied. At the same time the influence of pH and current density on COD removal efficiency with combined three-dimensional electrodes was also investigated, respectively. The optimal initial pH value of degradation is 3 (acid condition), and a minor COD removal increase follows higher current density.     

Designed synthesis of chlorine and nitrogen co-doped Ti3C2 MXene quantum dots and their outstanding hydroxyl radical scavenging properties

As a novel zero-dimensional(0D)material,metal carbides and/or carbonitrides(MXenes)quantum dots(MQDs)show unique photoluminescence properties and excellent biocompatibility.However,due to the limited synthesis methods and research to date,many new features have yet to be uncovered.Here,to explore their new properties and expand biological applications,chlorine and nitrogen co-doped Ti3C2 MXene quantum dots(Cl,N-Ti3C2 MQDs)were designed and synthesized,and their hydroxyl radical scavenging properties were investigated for the first time,revealing outstanding performance.Cl,N-Ti3C2 MQDs was directly stripped from bulk Ti3 AlC2 by electrochemical etching,while N and Cl are successfully introduced to carbon skeleton and Ti boundaries in the etching process by electrochemical reactions between selected electrolytes and Ti3C2 skeleton,respectively.The obtained Cl,N-Ti3C2 MQDs exhibit large surface-to-volume ratio due to small particle size(ca.3.45 nm)and excellent higher scavenging activity(93.3％)and lower usage(12.5 μg/mL)towards hydroxyl radicals than the previous reported graphene-based nanoparticles.The underlying mechanism of scavenging activity was also studied based on the reduction experiment with potassium permanganate(KMnO4).The reducing ability of the intrinsic Ti3C2 structure and electron donation of double dopants are the main contributors to the outstanding scavenging activity.     

TiB2-TiC复合粉的自蔓延高温还原合成

热分析结果表明,对于B₂O₃-TiO₂-Mg-C体系,可利用SHS还原技术合成出TiB₂-TiC陶瓷复合粉。其化学反应机理为:Mg先还原B₂O₃和TiO₂,新生的Ti与B和C反应生成TiB₂和TiC; TiO₂的还原经历了TiO₂→TiO→Ti的逐步过程。采用一定的酸洗工艺得到了纯净的TiB₂-TiC陶瓷复合粉。复合粉中包含六方片状TiB₂和圆球状TiC;复合粉中1μm以下颗粒质量百分数超过45%,87%以上的颗粒大小在3μm以下。在TiB₂-TiC中,TiC_<em>y以一种贫碳结构存在,物料中Ti被B或C结合形成TiB₂和TiC_<em>y,y的值为0.7483。