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： CATHODES   LITHIUM-ion batteries   ELECTRIC conductivity   ELECTROCHEMISTRY   ENERGY conversion  

摘要： FeF3 is a promising cathodematerial for lithium ion batteries but its poor electronic conductivity makes it non-practical. Here, we significantly improve the electrochemical activity of FeF3 by reducing the strong ionic character of Fe-F with the replacement of some F with N atoms. N-doped nanocrystalline FeF3/C achieves the best electrochemical performance among FeF3 compounds reported to date: similar to 95 mA h g(-1) at 21.1C discharge rate for 250 cycles. The results illustrate that the poor electronic conductivity of metal fluorides can be controlled by doping and this enables FeF3 or metal fluorides to be practically utilized in possible applications including energy conversion and storage.

关键词： Soil washing   HMs removal   EDDS recovery   Electrochemical treatment   Multistep washing  

摘要： Soil washing is an extensively used process for remediation of heavy metals contaminated soils. However the amount of fresh washing solution to be used represents a significant economical drawback of this process. This paper investigates the application of an electrochemical process (Fe/Fe electrodes couple) for the regeneration of a spent EDDS solution, containing Cu and major competitor cations (Ca, Fe, Mg, and Mn). The effect of current density, pH and conductivity of the washing solution on the recovery process performances was investigated. Current density showed the highest influence on Cu, Mg and Mn removal yields. Maximum removal yields reached 99% for Cu, 77% for Mn and 49% for Mg. No influence of the investigated parameters on Ca removal was observed, while an increase of Fe concentration due to anode dissolution occurred. Characterization of sludge produced from the 2 h electrochemical test (5 mA cm(-2), pH = 8, 8 mS cm(-1)) displayed concentrations of 2.8 g kg(-1) for Ca, 0.4 g kg(-1) for Cu, 535.6 g kg(-1) for Fe, 2.6 g kg(-1) for Mg. TCLP tests at pH 2.88 and 4.93 showed a low leaching percentage (Ca, 10-21%;Cu, 6-12%;Fe, 0.22% Mg, 27-36%). Multi-washing tests were carried out to assess the decrease of the chelating ability of the regenerated washing solution and the Cu extraction efficiency. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Modeling   Four-layered ANN   Electrochemical oxidation   K-fold cross validation  

摘要： This work is dealing with the performance and modeling of an electrochemical water treatment process. A bench-scale electrochemical reactor with working volume of 0.5L was applied to treat an azo dye, acid brown 14, as a typical pollutant in aqueous media. For the dye initial concentration of 50mg/L, the experimental data showed the optimum conditions of the process as: [NaCl]=5g/L, pH 6.4, and V=4V. Under the conditions, after 18min and consuming of low energy amount of 0.24Wh/L, 92% of decolorization efficiency (DE) was obtained. To model the process and simulate the obtained results, artificial neural network (ANN) method was used. Five effective operational parameters, i.e. reaction time, initial pH, applied voltage, supporting electrolyte, and the dye initial concentrations were considered as the network inputs;meanwhile, both of the DE and energy consumption (EC) criteria, were considered as the relevant network outputs. A four-layered feed-forward ANN, consisting of trainbfg learning algorithm and tansig as the transfer function in both hidden and output layers, was constructed. The neuron number structure of 5:4:6:2 and the iteration number of 600, showed best model-calibration ability. The K-fold cross-validation method showed high correlation coefficients (R-2) of 0.988 and 0.983 for the simulation of the DE and EC criteria, respectively.

关键词： Allura Red AC   Electrochemical oxidation   Electro-Fenton   Oxidation products   Photoelectro-Fenton  

摘要： The decolorization and mineralization of solutions containing 230 mg L-1 of the food azo dye Allura Red AC at pH 3.0 have been studied upon treatment by electrochemical oxidation with electrogenerated H2O2 (EO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Experiments were performed with a stirred tank reactor containing a boron-doped diamond (BDD) or Pt anode and an air-diffusion cathode to generate H2O2. The main oxidants were hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton's reaction between H2O2 and added Fe2+. The oxidation ability increased in the sequence EO-H2O2 < EF < PEF and faster degradation was always obtained using BDD. PEF process with BDD yielded almost total mineralization following similar trends in SO42-, ClO4- and NO3- media, whereas in Cl- medium, mineralization was inhibited by the formation of recalcitrant chloroderivatives. GC-MS analysis confirmed the cleavage of the -N=N- bond with formation of two main aromatics in SO42- medium and three chloroaromatics in Cl- solutions. The effective oxidation of final oxalic and oxamic acids by BDD along with the photolysis of Fe(III)-oxalate species by UVA light accounted for the superiority of PEF with BDD. NH4+, NO3- and SO42- ions were released during the mineralization. (C) 2015 Elsevier B.V. All rights reserved.

关键词： Electrochemical discharge machining   tool electrode   process parameters   tool design  

摘要： The electrochemical discharge machining is a combination of electrochemical machining and electrical discharge machining. The machining is achieved by chemical etching effect and melting of workpiece material due to electrical discharges. This process is used for a variety of nonconductive materials (glass, quartz, ceramic, Pyrex and so on) for the purpose of micromachining and specially for micro electro mechanical system applications. This article presents a comprehensive review of recent developments on tool electrode process parameters, which have resulted in enhanced efficiency and accuracy of the machining process. The tool electrode process parameters are shape, size, roughness, insulation and motion of tool and so on. These process parameters affect the process performance in terms of material removal rate, surface quality and dimensional accuracy of micromachined products. For example, spherical tool geometry provides five times higher material removal rate as compared to cylindrical tool geometry. The impact of electrochemical discharge machining process parameters associated with tool electrode is also discussed. A summary of review and proposed research directions is presented in this article.

关键词： Carbon materials   Biomass   Carbonization   Electrochemical capacitor   CO2 capture  

摘要： Preparing nitrogen-doped porous carbons directly from waste biomass has received considerable interest for the purpose of realizing the atomic economy. In this study, N-doped porous carbons have been successfully prepared from waste tobaccos (WT) by a simple pre-treatment process. The sample calcinated at 700 degrees C (WT-700) shows a micro/meso-porous structures with a BET surface area of 1104 m(2) g(-1) and a nitrogen content of ca. 19.08 wt.% (EDS). Performance studies demonstrate that WT-700 displays 170 F g(-1) electrocapacitivity at a current density of 0.5 Ag-1 (in 6M KOH), and a CO2 capacity of 3.6 mmolg(-1) at 0 degrees C and 1 bar, and a selectivity of ca. 32 for CO2 over N-2 at 25 degrees C. Our studies indicate that it is feasible to prepare N-enriched porous carbons from waste natural crops by a pretreatment process for potential industrial application. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Li2MnSiO4   Cathode Material   Li-Ion Battery   Solid-State   Silicate  

摘要： We report the fabrication and electrochemical properties of Li2MnSiO4 powders produced by various solid-state reactions, such as ball-, attrition-, and bead-milling. Li2MnSiO4 powders prepared by bead-milling had the smallest particle sizes (similar to 100 nm) and the largest amount of surface carbon (similar to 20 wt%), which were produced by adding sucrose during milling process. The surface carbon layer can improve electronic/ionic conductivity of Li2MnSiO4 as cathode material for lithium ion battery. As expected, the bead-milled Li2MnSiO4 powder electrode showed the best electrochemical performance of the electrode materials obtained by the various solid-state reactions. This is attributed to the small particle size and facile electronic transport through the conductive carbon layer on each Li2MnSiO4 particle.