Design of an ion-selective electrode analytical system for monitoring copper in electrochemical reactors

A flow-through cell using ion-selective electrodes has been designed for continuous on-line monitoring of electrochemical reactors. A full range of design considerations is discussed and the characteristics of the cell investigated. Optimal operating conditions are found, of which solution flow rate and constancy of temperature are particularly important. The cell was also designed to have a rapid response time and minimal dead volume so as to give continuous measurements of gradually changing metal ion concentrations. Performance has been evaluated using laboratory-simulated conditions and pilot-plant operation of the Ecocell, a rotating-cylinder electrode reactor for the electrowinning of copper from dilute solutions (10–1000 ppm).Nomenclature C ₀ initial metal ion concentration (ppm) - C _t metal ion concentration at timet (ppm) - E potential (V) - E ^{0, 1} a constant potential (V) - F Faraday constant (= 96498 C) - k apparent rate constant (s^–1) - r volumetric flow rate (cm³ s^–1) - R universal gas constant (= 8.314 J K^–1) - T absolute temperature (K) - t time (s) - V volume of gradient device (cm³) - relaxation time (s)     

The rotating cylinder electrode: its continued development and application

The application of rotating cylinder electrodes (RCEs) in electrochemistry has been reviewed for the period 1982–1995. Among the applications highlighted are the novel design of cell geometries and reactors for a range of electrochemical processes, voltammetry and analysis, electrodeposition and corrosion. This range amply indicates the widespread acceptance of the RCE for studies in a number of interdisciplinary fields.     

因子分析及其在过程监控中的应用

概率主元分析（PPCA）模型是因子分析（FA）模型的一种特殊形式，而主元分析（PCA）模型是PPCA模型的一种特例。PPCA和PCA已经在过程监控中得到了成功的应用，但是这两种方法的约束条件较多，而FA约束条件少，因此更能反映数据的本质特征。本文将FA引入工业过程监控，通过期望最大化（EM）算法建立FA模型，然后提出基于FA的监控指标，并讨论了因子个数的选择方案。在田纳西-伊斯曼（TE）过程中的应用结果以及与PCA、PPCA监控结果的对比表明了该方法的优越性。     

动态因子分析模型及其在过程监控中的应用

在复杂工业系统的监控中,因子分析（FA）方法不需要专业的机理知识,应用系统日常运行数据建立模型,充分考虑了模型误差的普遍意义,具有较大的推广价值。针对实际过程的动态特性,基于自回归（AR）方式扩展过程变量数据矩阵,本文提出一种动态因子分析（DFA）的数据建模方法,充分提取了变量的自相关信息和互相关信息。另一方面,将DFA引入过程监控中,构建统计量作为监控指标,分别衡量变量的特征信息和误差信息,从而实现对动态过程运行状况的监控与评估。在Tennessee-Eastman（TE）过程中的应用研究,反映了这种方法的优越性。     

多通道TiO_2超滤膜的制备及其在印染废水中的应用

以多通道α-Al2O3陶瓷微滤膜为支撑体,采用溶胶凝胶法制备完整TiO2超滤膜。通过扫描电镜(SEM)表征膜的形貌,采用错流过滤方式考察膜的纯水通量、截留相对分子质量及分离性能。结果表明:制备的多通道TiO2超滤膜,其膜层表面完整,无裂缝、针孔等缺陷且厚度均匀,纯水通量为1.08×10-3L/(m2.h.Pa),截留相对分子质量为9 000。对直接黑OB染料及退浆废水中聚乙烯醇(PVA)的截留率均达到99%以上,截留效果显著。     

铁谱定性分析技术及其在水泥行业油液监测中的应用

采用铁谱定性分析技术,从材质、形貌特征、生成机理及来源等方面来分析铁系磨粒、铜合金磨粒和巴氏合金磨粒,判断机械设备摩擦副的运行状态及可能存在的异常磨损情况,对指导设备的维护具有重要意义。通过对水泥行业的设备进行油液监测,可发现辊压机减速齿轮箱是否出现严重磨损,推测设备是否存在故障,经现场拆机检查证实。     

旋流在气流床气化炉中的应用

在气流床气化炉内高温高压的环境下,气固混合是影响气化炉效率的重要因素,而旋流在强化气固混合方面已在燃烧中得到广泛使用,文中综述了旋流在气流床气化炉中的应用。首先介绍了旋流的数学描述,包括旋流的概念,旋流N-S方程的表示方法以及其解析解,旋流的解析解均是在一定假设前提下得到的,具有一定的局限性;其次,介绍了旋流的特性和生成方式,主要通过切向入口、旋流叶片和机械旋转引入旋流;然后介绍了旋流在气化炉中的应用,包括喷嘴旋流和炉膛旋流2种,并结合具体结构展示了旋流的作用,主要有增强混合和便于排渣;最后对旋流在气化炉中的应用进行了总结和展望。     

The evaluation of the polarization resistance in a tubular electrode and its application to the hydrogen electrode reaction

An alternative method for the determination of the kinetic parameters involved in the elementary steps of the reaction mechanism of the hydrogen electrode reaction is proposed. It is based on the determination of the variation of the polarization resistance in a tubular platinum electrode with a laminar flow of electrolyte as a function of the activity of protons of the electrolyte solution. A theoretical expression that relates the experimental variables and the equilibrium polarization resistance is developed, which takes into account the current distribution along the electrode surface. The results are compared with others obtained previously, contributing to the verification of the kinetic mechanism through a completely different experimental procedure.     

A wall-jet electrode reactor and its application to the study of electrode reaction mechanisms Part I: Design and construction

A wall jet electrode reactor possessing a laminar flow regime, suitable for mechanistic studies, is reported. This reactor is different from those described in the literature in the size of its working electrode surface area. The reactor is evaluated by means of mass transport-limited current measurements using as a model reaction the reduction of ferricyanide ions at a platinum electrode surface from a 0.01 m K₃Fe(CN)₆-0.01 m K₄Fe(CN)₆ solution containing 1 m KCl as supporting electrolyte. The dependence of the mass transport-limited current on the crucial reactor parameters — the volume flow rate V _f (m³ s^–1), the nozzle diameter a (m) and the radius of the working electrode R (m) — is established and verified by theoretical predictions. The reactor is shown to have the desired wall jet hydrodynamics for: 1.6 × 10^–6 V _f 4.3 × 10^–6 m³ s^–1, 1.5 × 10^–3 a 3 × 10^–3 m and 1.5 × 10^–2 R 2 × 10^–2 m.List of symbols a nozzle diameter (m) - C _A concentration of A in the bulk (mol m^–3) - D _A diffusion coefficient of A (m² s^–1) - F Faraday's constant (C mol^–1) - dynamic viscosity (gm^–1 s^–1) - H distance between the working electrode and the tip of the nozzle (m) - I _lim mass-transport-limited current (A) - k _r constant linking the typical velocity of the wall-jet to the mean velocity in the nozzle - v kinematic viscosity (m² s^–1) - n number of electrons exchanged - density (g m^–3) - R radius of the working electrode (m) - t time (s) - V _f volume flow rate (m^–3 s^–1)     

三维有序结构聚苯胺/石墨烯纳米复合材料的制备及其在超级电容器电极中应用

用硼氢化钠(NaBH_4)还原氧化石墨烯得到还原石墨烯(rGO)分散液,rGO分散液与苯胺在酸性条件下原位聚合得到高比表面积三维有序结构的聚苯胺/石墨烯纳米复合材料。由场发射扫描电镜(FESEM)、透射电镜(TEM)、X射线光电子能谱(XPS)和X射线衍射(XRD)对其表面形貌和结构进行表征。结果表明:复合材料的比表面积高达136.9 m~2/g,高于纯聚苯胺的比表面积(32.71 m~2/g);直径10~20 nm的聚苯胺纳米棒均匀地垂直生长在石墨烯表面。在0.5 A/g的电流密度下,复合材料比电容达到358 F/g,大于石墨烯和聚苯胺的比电容;当充放电电流密度由0.5 A/g增加到10 A/g时,电容保留率达74.3%,表现出增强的倍率性能;在10 A/g高电流密度下,经过500次的充放电循环后容量保持率达到83.7%。     

One-step fabrication of CuO nanoribbons array electrode and its excellent lithium storage performance

CuO nanoribbons array (NRA) electrode was fabricated by developing a one-step synthesis route, which consists of advantages of large-scale, fast, and without using any surfactant or template. The structure and electrochemical properties of the CuO NRA electrode were examined by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV) and galvanostatic cycling. The results demonstrated that the CuO NRA electrode can deliver a reversible capacity as high as 608 mAh g⁻¹ up to 275th cycle. The excellent cycleability, the high capacity retention and the high rate-capability of the CuO NRA electrode is attributed to its peculiar nanostructure with large surface area, numerous interspaces of the CuO nanoribbons, and the solid adhesion of the active material to Cu current collector.     

Probabilistic monitoring of chemical processes using adaptively weighted factor analysis and its application

As a probabilistic statistical method, factor analysis (FA) has recently been introduced into process monitoring for the probabilistic interpretation and performance enhancement of noisy processes. Generally, FA methods employ the first several factors that are regarded as the dominant motivation of the process for process monitoring; however, fault information has no definite mapping relationship to a certain factor, and useful information might be suppressed by useless factors or submerged under retained factors, leading to poor monitoring performance. Weighted FA (WFA) for process monitoring is proposed to solve the problem of useful information being submerged and to improve the monitoring performance of the GT² statistic. The main idea of WFA is firstly building a conventional FA model and then using the change rate of the GT² statistics (RGT²) to evaluate the importance of each factor. The important factors tend to have larger RGT² values, and the larger weighting values are then adaptively assigned to these factors to highlight useful fault information. Case studies on both a numerical process and the Tennessee Eastman process demonstrate the effectiveness of the WFA method. Monitoring results indicate that the performance of the GT² statistic is improved significantly compared with the conventional FA method.     

Electrochemical fabrication and electrocatalytic characteristics studies of gold nanopillar array electrode (AuNPE) for development of a novel electrochemical sensor

Gold nanopillar array electrodes were prepared by electrochemical deposition of gold into the nanopores of anodic aluminum oxide membrane placed onto the gold thin film electrode surface, which was in advance modified with cysteamine self-assembled monolayer as an anchoring layer. The Au nanopillar electrode is electrochemically stable and consists of highly dense, upstanding pillars assembled on the cysteamine monolayer. The structural morphology and chemical composition of the nanoarray electrode was characterized by field emission scanning electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Electrochemical measurements indicate that the Au nanopillar electrode possesses high electrocatalytic activities in the reduction of hydrogen peroxide and molecular oxygen, especially in glucose oxidation due to its higher electroactive surface area. The electro-oxidation studies of several electroactive neurotransmitters demonstrate that the nanopillar electrode can be utilized as a promising material for the construction of novel electrochemical sensor.     

Polyaniline nanowire array encapsulated in titania nanotubes as a superior electrode for supercapacitors

Conducting polymer with 1D nanostructure exhibits excellent electrochemical performances but a poor cyclability that limits its use in supercapacitors. In this work, a novel composite electrode made of polyaniline nanowire-titania nanotube array was synthesized via a simple and inexpensive electrochemical route by electropolymerizing aniline onto an anodized titania nanotube array. The specific capacitance was as high as 732 F g(-1) at 1 A g(-1), which remained at 543 F g(-1) when the current density was increased by 20 times. 74% of the maximum energy density (36.6 Wh kg(-1)) was maintained even at a high power density of 6000 W kg(-1). An excellent long cycle life of the electrode was observed with a retention of ～86% of the initial specific capacitance after 2000 cycles. The good electrochemical performance was attributed to the unique microstructure of the electrode with disordered PANI nanowire arrays encapsulated inside the TiO(2) nanotubes, providing high surface area, fast diffusion path for ions and long-term cycle stability. Such a nanocomposite electrode is attractive for supercapacitor applications.     

水泥企业制造执行系统MES应用开发

介绍制造执行系统MES应用特点，结合水泥企业生产实际需要，采用C／S、B／S混合模式以及ASP．NET、VFP、SQL Server 2000和组态王6．5设计开发水泥企业MES系统。给出了整个系统的设计原理、软硬件结构图，着重分析说明了B／S子系统和后勤管理模块的开发过程、技术关键及具体实现方法和运行结果。该系统已在福建省某水泥有限公司成功运行。     

Automated multichannel system for in-line monitoring of float-glass ribbon thickness in the hot zone of an annealing furnace

The advances and 10 years of experience in operating automated multichannel systems for in-line monitoring of float-glass ribbon thickness, which led to serial production of such systems, are summarized.     

Balanced multiple weighted linear discriminant analysis and its application to visual process monitoring

Visual process monitoring is important in complex chemical processes. To address the high state separation of industrial data, we propose a new criterion for feature extraction called balanced multiple weighted linear discriminant analysis(BMWLDA). Then, we combine BMWLDA with self-organizing map(SOM) for visual monitoring of industrial operation processes. BMWLDA can extract the discriminative feature vectors from the original industrial data and maximally separate industrial operation states in the space spanned by these discriminative feature vectors. When the discriminative feature vectors are used as the input to SOM, the training result of SOM can differentiate industrial operation states clearly.This function improves the performance of visual monitoring. Continuous stirred tank reactor is used to verify that the class separation performance of BMWLDA is more effective than that of traditional linear discriminant analysis, approximate pairwise accuracy criterion, max–min distance analysis, maximum margin criterion, and local Fisher discriminant analysis. In addition, the method that combines BMWLDA with SOM can effectively perform visual process monitoring in real time.     

A carboxyalkanethiol monolayer modified electrode for blocking of ascorbic acid oxidation and its application to a biosensor

Upon the application of amperometric biosensor to the biological fluid, ascorbic acid interferes the amperometric determination of analytes, because the oxidative potential of ascorbic acid is lower than that of electro active substances such as H₂O₂ produced by the enzymatic reaction. In this study we propose a method to block ascorbic acid based on the electrostatic interaction with self-assembled monolayer (SAM) and its application of the surface modified electrode to biosensor. In order to form SAM on the gold electrode with carboxyl group, 7-carboxy-heptanethiol (7-CHT) was used. The 7-CHT modified electrode did not show anodic response to ascorbic acid, but oxidized phenanthroline cobalt complex [Co(phen)₃²⁺], which can be used as a mediator of biosensor. Thus, the 7CHT-modified electrode was applied to biosensor mediated with Co(phen)₃²⁺. Fructose dehydrogenase (FDH) was immobilized to the 7-CHT modified electrode. Fructose was determined selectively with the FDH/7-CHT modified electrode at the range of 0.2-2 mM.     

Ag nanowires and its application as electrode materials in electrochemical capacitor

Silver nanowires were synthesized on a large scale by using anodic aluminum oxide (AAO) film as templates and serving ethylene glycol as reductant. Their morphological and structural characterizations were characterized with field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and selected area electron diffraction (SAED). The electrochemical properties of silver nanowires as electrode materials for electrochemical capacitors were investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge technique in 6 M KOH aqueous electrolyte. The Ag₂O/Ag coaxial nanowires were formed by the incomplete electrochemical oxidation during the charge step. The maximum specific capacitance of 987 F g^?1 was obtained at a charge–discharge current density of 5 mA cm^?2.     

Simulation and optimization of a flow battery in an area regulation application

Flow batteries have the potential to provide ancillary grid services such as area regulation. In this paper, a hypothetical 2 MW flow battery is simulated in an area regulation application to find the optimal energy-to-power ratio that maximizes the net present value (NPV) of a 10 year project based on a range of installation costs. Financial and operational results are presented, and candidate battery chemistries are discussed. A simplified model of battery installation costs (dollars per kW h) resulted in a positive NPV for installation costs below $500 kW⁻¹ h⁻¹. For installation costs between $500 kW⁻¹ h⁻¹. For installation costs between 300 and $500 kW⁻¹ h⁻¹, an optimal energy-to-power ratio is 1.39. The traditional advantage of decoupling power and energy capacity may not be realized in area regulation; therefore hybrid flow batteries may be more appropriate. Zinc-bromine and iron-chromium chemistries might fit well with this application, along with lower-cost flow battery chemistries in the future.