关键词： Degradation   Power conversion efficiency   Electrodes   Electrolysis   Materials  

摘要： An extensive study of the influence of the operational variables in the electrochemical degradation of perchloroethylene in water has been carried out using an electrochemical filter-press reactor. The influences of the initial concentration, volumetric flow, and electrode geometry and nature on the kinetics, degradation efficiency, and mechanism have been analyzed by determining the values of process performance parameters such as fractional conversion, degradation efficiency, mass balance error, and selectivity. The best results obtained were a fractional conversion higher than 85%, degradation efficiencies of 65%, selectivities close to 0.8, and energetic consumption around 3 kWh m(-3) obtained with two-dimensional electrodes. Three-dimensional carbon electrodes did not provide a more competitive option.

关键词： Stainless steel   Electrochemical noise   Pitting corrosion   Oxygen reduction  

摘要： The use of electrochemical noise (EN) measurements for the investigation and monitoring of corrosion has allowed many interesting advances in the corrosion science in recent years. A special advantage of EN measurements includes the possibility to detect and study the early stages of localized corrosion. Nevertheless, the understanding of the electrochemical information included in the EN signal is actually very limited. The role of the cathodic process on the EN signals remains uncertain and has not been sufficiently investigated to date. Thus, an accurate understanding of the influence of the cathodic process on the EN signal is still lacking. On the basis of different kinetics of the oxygen reduction it was established that the anodic amplitude of transients arising from pitting corrosion on stainless steel can be decreased by the corresponding electron consumption of the cathodic process. Therefore, the stronger the electron consumption, the weaker the anodic amplitude of the EN signal becomes. EN signals arising from pitting corrosion on stainless steel can be measured because the cathodic process is inhibited by the passive layer. This was confirmed by means of EN measurements under cathodic polarisation. Since the cathodic process plays a decisive role on the form of transients arising from pitting corrosion, its influence must be considered in the evaluation and interpretation of the EN signals. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： pesticides   anodic oxidation   electro-Fenton   BDD anode   hydroxyl radical   advanced oxidation processes  

摘要： In the present work, a comparative study on the degradation of a mixture of three pesticides (chlortoluron, carbofuran and bentazon) has been carried out by electrochemical advanced oxidation processes such as anodic oxidation and electro-Fenton using boron-doped diamond (BDD) anode. These processes are based on the in situ production of hydroxyl radical, a highly strong oxidant, which allows the degradation of organic pollutants until their mineralisation into CO2 and H2O. Obtained results showed that more than 90% of TOC removal was obtained in 4 h of treatment by both processes. The mineralisation rate was found to be higher for electro-Fenton (BDD) than that of the anodic oxidation. Also, the electro-Fenton (BDD) can mineralise the pesticide solution in 90 min while anodic oxidation requires 150 min. The released inorganic ions, such as chloride, nitrate, sulphate and ammonium, are identified and their kinetic evolution was measured by ion chromatographic analyses.

关键词： advanced oxidation   electrochemical treatment   electro-Fenton   ferrous iron   hydroxyl radical   hypochlorous acid  

摘要： The feasibility of an electrochemically assisted Fenton treatment using a Fenton-type reaction of ferrous iron (Fe2+) and hypochlorous acid (HOCl) is discussed in this research. The reactor used was composed of an undivided single cell with a ruthenium dioxide-coated titanium anode and a stainless steel cathode, in which Fe2+ and HOCl were catalytically regenerated from ferric iron at the cathode and chloride ion at the anode, respectively. Although the reactor functioned well, the degradation rate of 1,4-dioxane as a hydroxyl radical probe decreased at the current density more than 6.92mAcm(-2). The decrease in degradation rate was inferred to be caused by the vain consumption of hydroxyl radicals by excess HOCl and the deposition of ferric hydroxide on the cathode at relatively high current density. The current efficiency of 1,4-dioxane removal remained more than 90% at the current density less than 6.92mAcm(-2) and the iron concentration not less than 1.0 mmolL(-1). Consequently, this technique is thought to be applicable to the treatment of wastewater containing high concentration of chloride ion such as landfill leachate, scrubber wastewater from incineration plants, etc.

关键词： electrochemical sensors   wireless   process control  

摘要： Wireless sensors are widely used in analytical chemistry. Their utilization in control will make the feed-back of the quality of processes in real time possible followed by immediate remediation of the problems regarding quantity and quality of by-products and final products. The mini review will outline the current situation in interactive-intelligent-real-time process technology with remote on-site wireless sensors as well as giving aspects of the historical background of process and process control from wired to wireless.

关键词： switchable interface   local pH change   enzyme   modified electrode   magnetic nanoparticles   logic gate  

摘要： An electrode surface modified with a pH-sensitive polymeric brush was reversibly activated by local pH changes produced in situ by glucose oxidase associated with magnetic nanoparticles confined at the surface in the presence of an external magnet. The system mimics Boolean AND logic gate, with the magnetic and chemical input signals stimulating the electrochemical reactions at the switchable interface. Biomedical applications of the "smart" interface controlled by enzymatic reactions through local pH changes are anticipated in various implantable biomedical devices.

关键词： Chlorine dioxide   Electrochemical generation   Un-divided electrochemical cell   Un-buffered solution   Optimization of process parameters  

摘要： Chlorine dioxide is potentially a powerful oxidant with environmentally compatible application in several strategic areas relating to pollution control typically for water disinfection, and its sustained production is a key factor for its successful application. Although increased attention has been paid for on-line chlorine dioxide generation by several chemical and electrochemical methods, the details are mostly confined as patents. We studied in this work the electrochemical generation of chlorine dioxide from an un-buffered solution of sodium chlorite and sodium chloride mixture in an un-divided electrochemical cell under constant current mode, with a view to optimize various process parameters, which have a direct bearing on the chlorine dioxide formation efficiency under laboratory conditions. The effect of feed flow rate (10-150 ml min(-1)), feed solution pH (2.3-5.0), concentration of sodium chloride (0-169.4 mM), concentration of sodium chlorite (0-7.7 mM), and the applied current (100-1200 mA) on the formation of dissolved ClO2 gas in solution and the pH of the product-containing solution was investigated by performing single pass experiments, with no circulation, in a cell set-up with Ti/IrO2 anode and Ti/Pt cathode. The current efficiency and the power consumption were calculated for the optimized conditions. (C) 2008 Elsevier B.V. All rights reserved.

关键词： Chemical mechanical polishing  

摘要： The effects of process parameters on electrochemical characteristics of silicon wafers during chemical mechanical polishing (CMP) as well as under static conditions were studied by dc polarization and open-circuit potential (OCP) techniques. All the process parameters strongly affected the electrochemical behaviors and polishing rates. The corrosion current density first increased rapidly when raising polishing pressure, rotation speed, and silica solid content and then began to slow down. The polishing rate declined gradually with the increase of polishing time due to the pad surface plastic deformation during CMP. Also, the CMP process of silicon wafers could be considered as a sequential formation and removal of a film, which was confirmed by testing the change of OCP. A low surface roughness could be obtained after CMP. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3097182] All rights reserved.

关键词： 农村电气化建设   进程   德政工程   农网改造   城网改造   供电公司   发展战略   新农村  

摘要： 新农村电气化建设是继农网改造、城网改造和“户户通电”工程之后又一项造福于民的“民心工程”、“德政工程”。近两年来，河北省沙河市供电公司紧紧围绕“新农村、新电力、新服务”农电发展战略，把推进新农村电气化建设作为工作的重中之重，坚持从目标上明确，从措施上保证，从载体上创新，使新农村电气化建设取得了显著成效。

关键词： Diuron   Toxicity   Hydroxyl radicals   Electro-Fenton process   Oxidation products   Microtox  

摘要： Diuron (N'-[3,4-dichlorophenyl]-N,N-dimethylurea) is a herbicide belonging to the phenylurea family, widely used to destroy weeds on uncultivated surfaces. Because of its toxicity for aquatic organisms and suspicion of being carcinogenic for humans, diuron is the object of growing environmental concern. Therefore, we have developed the electro-Fenton method, an electrochemical advanced oxidation process (EAOP), to degrade diuron in aqueous medium, and we have studied the evolution of the toxicity of treated solution during the process. Indeed, the EAOPs catalytically generate hydroxyl radicals that oxidize the persistent organic pollutants, and can ultimately destroy and mineralize them. But, sometimes, relatively toxic organic metabolites are formed during the oxidation reaction. In this work, the evolution of toxicity of diuron aqueous solutions was studied at different initial concentrations, during treatment by the electro-Fenton method. Samples were collected at various electrolysis times and mineralization degrees during the treatment. The toxicity of the samples was measured using the bacteria Vibrio fischeri (Microtox) and the green alga Scenedesmus obliquus. Our results demonstrated that the toxicity of diuron aqueous solutions (concentrations = 3.0-27.6 mg L-1) varied considerably with time. The formation and disappearance of several metabolites, having toxicity often stronger than that of the initial herbicide, were observed. To improve the efficiency of water decontamination, the electro-Fenton method should be applied during a time long enough (several hours) and at relatively high electrolysis current (I = 250 mA) to reach a nearly complete mineralization of the herbicide in the aqueous medium. (C) 2008 Elsevier Ltd. All rights reserved.