关键词： MICROCHEMISTRY   INFRARED spectroscopy   ELECTROCHEMISTRY   SYNCHROTRON radiation   OXIDATION-reduction reaction   CARBON electrodes  

摘要： We describe a method for addressing redox enzymes adsorbed on a carbon electrode using synchrotron infrared microspectroscopy combined with protein film electrochemistry. Redox enzymes have high turnover frequencies, typically 10-1000 s(-1), and therefore, fast experimental triggers are needed in order to study subturnover kinetics and identify the involvement of transient species important to their catalytic mechanism. In an electrochemical experiment, this equates to the use of microelectrodes to lower the electrochemical cell constant and enable changes in potential to be applied very rapidly. We use a biological cofactor, flavin mononudeotide, to demonstrate the power of synchrotron infrared microspectroscopy relative to conventional infrared methods and show that vibrational spectra with good signal-to-noise ratios can be collected for adsorbed species with low surface coverages on microelectrodes with a geometric area of 25 x 25 mu m(2). We then demonstrate the applicability of synchrotron infrared microspectroscopy to adsorbed proteins by reporting potential-induced changes in the flavin mononudeotide active site of a flavoenzyme. The method we describe will allow time resolved spectroscopic studies of chemical and structural changes at redox sites within a variety of proteins under precise electrochemical control.

关键词： Electrochemical discharge machining   Micromachining   ECDM variants   Triplex hybridization  

摘要： Electrochemical discharge machining (ECDM) is a hybrid non-conventional machining process, used to machine electrically conductive and non-conductive materials. It is a preferred process to fabricate micro scale features like micro holes, micro channels, microgrooves and 3-dimensional intricate shapes on variety of materials. In order to improve the efficacy of ECDM process, certain technical augmentations are provided with basic configuration of ECDM. These augmentations result in developments of ECDM process variants. Further, research community has developed ECDM based triplex hybrid methods for further process enrichment. This review article presents a comprehensive review of these recent developments in ECDM process, its variants and their triplex hybrid methods. The future research possibilities are identified and presented as research potentials. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Operating cost   Electrochemical peroxidation process   Acid yellow 194   Response surface methodology  

摘要： In this study, electrochemical peroxidation was employed to remove color and total organic carbon (TOC) from co-complex (acid yellow 194) dye using iron electrodes in a batch-mode operation. The effects and relationships of the process variables were evaluated, and optimizations were carried out using response surface methodology to maximize removal efficiencies and minimize operating costs in relation to energy, electrode, and chemical (such as H2O2) consumptions. The initial pH (2.0-6.0 pH(i)), conductivity (500-2,500 mu S/cm, k), initial dye concentration (100-800mg/L, C-0), current density (10-30A/m(2), j), operating time (4-20min, t), and dosage of H2O2 (2-10mM or 175-860 mu L/L, [GRAPHICS] ) were selected as independent variables. The proposed models fit very well with experimental data, evidenced by high R-2 correlation coefficients (>90%). Maximum color removals were 98 and 80% when C-0 was 275 and 625mg/L, respectively. In contrast, maximum TOC removals were poor (52 and 40% when C-0 was 275 and 625mg/L, respectively). On the other hand, color and TOC removals were found to be 86 and 33.5%, respectively, at optimum conditions (C-0, 275mg/L;pH(i) 3;[GRAPHICS] , 1.010 mu S/cm;[GRAPHICS] , 5.1mM;j, 15A/m;and t, 8.02min). The calculated operating cost at optimized conditions was 0.647euro/m.

关键词： 中国汽车产业   大众汽车   进程   电气化   混合动力   本土化生产   中国市场   品牌计划  

摘要： 大众汽车全力推进纯电动与混合动力车型的研发进程。在未来三至四年内，大众汽车品牌计划在中国市场，推出七款全新的本土化生产的纯电动或捅电式混合动力车型。为了达成这个目标，大众汽车还计划在中国设立一个全新的设计与研发中心。

关键词： Copper-phthalocyanine dye   Electrochemical oxidation   Electro-Fenton   Oxidation products   Photoelectro-Fenton  

摘要： The degradation of the copper-phthalocyanine dye Reactive Blue 15 dye in sulfate medium has been comparatively studied by electrochemical oxidation with electrogenerated H2O2 (EO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Experiments with 100 cm(3) solutions of 0.203 mmol dm(-3) dye were performed with a stirred tank reactor containing a boron-doped diamond (BDD) anode and an air-diffusion cathode for continuous H2O2 production. Experimental conditions of pH 3.0 and 0.50 mmol dm(-3) Fe2+ as catalyst were found optimal for the EF process by the predominant oxidation with hydroxyl radicals formed in the bulk from Fenton's reaction between added Fe2+ and generated H2O2. The kinetics of Reactive Blue 15 abatement was followed by reversed-phase HPLC and always obeyed a pseudo-first-order reaction. The decolorization rate in EO-H2O2 was much lower than dye decay due to the formation of large quantities of colored intermediates under the action of hydroxyl radicals generated at the BDD anode from water oxidation. In contrast, the color and dye removals were much more rapid in EF and PEF by the most efficient oxidation of hydroxyl radicals produced from Fenton's reaction. PEF was the most powerful treatment owing to the photolytic action of UVA irradiation, yielding 94% mineralization after 360 min at 66.7 mA cm(-2). The effect of current density over the performance of all methods was examined. LC-MS analysis of treated solutions allowed the identification of 25 aromatic and heteroaromatic products and 30 hydroxylated derivatives. Tartaric, acetic, oxalic and oxamic acids were quantified by ion-exclusion HPLC. Acetic acid was the only product remaining after PEF and its large persistence explained the almost total mineralization achieved by this process. Chloride, sulfate, nitrate and in smaller proportion, ammonium ions were released to the solution in all cases. A plausible reaction sequence for Reactive Blue 15 mineralization has been finally proposed. (C

关键词： Boron-doped diamond   Electrochemical treatment   Optimization   Response surface methodology   Sulfadiazine  

摘要： Electrochemical oxidation and process optimization of sulfadiazine antibiotic were investigated in a batch electrochemical reactor using boron-doped diamond (BDD) anode. Reaction conditions were operated at 200-1,000mg/L sulfadiazine concentration, 0-8g/L supporting electrolyte (NaCl), 4-20mA/cm(2) current density, and 25-45 degrees C reaction temperature at 120min reaction time. Process optimization was accomplished through response surface methodology in central composite designed experiments. Optimum operating conditions were determined under specified cost-driven constraints at 13.4mA/cm(2) current density, 618mg/L sulfadiazine concentration, 3.6g/L electrolyte concentration, and 36 degrees C reaction temperature. In a specific batch run at response surface-optimized conditions, the responses for sulfadiazine removal, COD removal, EOX, and energy consumption were achieved as 100.0%, 95.5%, 0.0617, and 94.3 kWh/kg CODr, respectively. Relative error values in this optimization study for the electrochemical oxidation of sulfadiazine antibiotic using BDD anode were obtained below 2%.

关键词： Electrochemical machining (ECM)   20MnCr5 alloy steel   Material removal rate (MRR)   Surface roughness (R-a)   Particle swarm optimization (PSO)   Desirability function (DF)  

摘要： Electrochemical machining (ECM) of metals, particularly steels, plays an important role in numerous industrial applications. The alloy steels especially 20MnCr5 are used as good wear resistant in the applications of boxes, piston bolts, spindles, camshafts, gears, shafts and other mechanical controlling parts. Machining of above complicated shapes with conventional machine tools is cumbersome task. Hence, investigation was made to study the electrochemical machining characteristics of 20MnCr5 alloy steel. Hydrogen peroxide (H2O2) mixed aqueous NaCl was used as electrolyte in order to enhance the machining performance of ECM. The predominant ECM process parameters such as applied voltage (V), inter-electrode gap (IEG) and electrolyte concentration (EC) were considered to study its influence on the material removal rate (MRR) and surface roughness (R (a)). Microstructure of surface of the 20MnCr5 steel specimen machined with ECM was studied to understand the effect of electrolyte during the machining. The contour plots were generated to study the effect of process parameters as well as their interactions. The optimized machined conditions found with particle swarm optimization (PSO)-desirability function (DF) optimizer were quite close with experimental results. Additional advantage of H2O2 presence was noted that scales formed on flow path of electrolyte were completely removed.

关键词： Electrochemical-Fenton process   Heterogeneous catalyst   Magnetite   Palladium   Pentachlorophenol  

摘要： Fe3O4 nanospheres with uniformly distributed Pd nanoparticles (Fe3O4-Pd) were prepared and used to catalyze the electrochemical-heterogeneous Fenton (EC-HF) degradation of pentachlorophenol (PCP). Synthesis of the catalyst was confirmed by X-ray diffraction and high-resolution transmission electron microscopy/energy-dispersive X-ray spectroscopy. The catalytic performance of the developed catalyst was assessed and the roles of Pd in the mechanism of Fe ion leaching and PCP degradation enhancement were elucidated. The conditions of 5 V, pH 2.3, and 288 K gave a removal efficiency of 100% within 30 min with the catalyst, compared with 17.2% for the EC process alone. Pd nanoparticles altered the Fe leaching mechanism and enhanced both homogeneous and heterogeneous Fenton reactions when they were loaded on the Fe3O4 surface. The effects of operating conditions such as applied potential, pH, catalyst dose, solution temperature and initial PCP concentration were investigated. The results showed that a higher applied potential and solution temperature favored larger kinetic constants, whereas kinetic constants decreased with increasing solution pH. As the initial PCP concentration increased, the initial degradation rate increased while the kinetic constant decreased. The optimal catalyst dose was 50 ppm. In addition, the Fe3O4-Pd reusability was evaluated. (C) 2015 Elsevier B.V. All rights reserved.

关键词： Electrooxidation  

摘要： The purpose of this paper is the investigation of the capability of electrochemical methods, such as electrocoagulation, electrooxidation and electro-Fenton for decolorization and degradation of synthetic aqueous solutions and actual dye house effluents containing nylanthrene red reactive dye. All electrochemical experiments with the synthetic dye solutions were conducted in electrochemical cell of volume 500 ml containing 200 mL of dye solution at concentration 50 mg/L and interelectrode distance of 1 cm. The three different electrochemical processes were analyzed, and their removal efficiencies were measured and evaluated. In addition, a flow diagram is designed for a continuously operated electrochemical process for remediation of synthetic and actual dye house effluents laden with nylanthrene dye. In the electrocoagulation process with aluminum electrodes, the colored aqueous dye solution was treated at the applied current densities of 5, 10 and 15 mA/cm2 and was quantitatively decolorized in 11, 9 and less than 6 minutes of electroprocessing time respectively. The electrooxidation process conducted with Ti/Pt and boron doped diamond (BDD) electrodes, at the applied current density of 10 mA/cm2 led to the quantitative decolorization and destruction of the dye in 25 and 15 min respectively. In the electro-Fenton process with iron electrodes, supply of added hydrogen peroxide and applied current density of 10 mA/cm2, complete decolorization and degradation of the nylanthrene red dye occurred in 6 min. The actual polyamide textile dyeing effluent of same volume 200 mL with initial turbidity of 114 NTU and COD of 1755 mg/L was treated by electrocoagulation at the same applied current density of 10 mA/cm2. The turbidity was quantitatively eliminated in only 10 min, while COD was reduced by 74.5 % in 40 minutes of electrolysis time.

关键词： Heat affected zone  

摘要： The process parameter in the non-traditional machining process is an important aspect of enhancing the performance parameter. Precision machining and machining of complex part is a challenging task which is time consuming and expensive. Therefore, the optimal values of process parameters should be selected so that performance parameter, like, material removal rate (MRR), radial overcut (ROC) and heat affected zone (HAZ), etc., can be optimised. In this paper, a recently developed optimisation technique firefly algorithm (FA) is considered for finding out the optimal solution. The FA technique is attempted to two non-traditional machining processes, electrochemical micromachining (EMM) and electrochemical discharge machining (ECDM). The variations of process parameters w.r.t performance parameter are represented graphically for better and effective study of the machining processes. The results of EMM and ECDM obtained by using FA are compared and it is found that the results obtained by the application of FA are better compared to the previous researcher's result. © 2016 Inderscience Enterprises Ltd.