壳聚糖修饰电极超声辅助电化学测定碘离子

采用滴涂法制备壳聚糖修饰玻碳电极,运用线性扫描溶出伏安法和差分脉冲伏安法测定水中的I-。研究了修饰液的浓度、底液的pH、扫描速度、富集时间及超声对电化学行为的影响。线性扫描溶出伏安法对水中的I-的检出限为1.8×10-5mol·L-1,差分脉冲伏安法检出限可达4.0×10-10mol·L-1,采用超声辅助伏安法能够进一步提高检测的灵敏度,建立了一种快速检测水中微量I-的方法。     

PVC-十二烷基苯磺酸钠碳糊修饰电极测定水中的镉离子

研究了镉离子在PVC-十二烷基苯磺酸钠碳糊修饰电极上的电化学行为,在pH 5.0的B-R缓冲溶液介质中,镉离子在阳极溶出伏安曲线的-0.78 V(vs.SCE)处有一个灵敏的氧化峰.优化了测定条件,建立了测定镉离子的分析方法.峰电流与镉离子的浓度在4.0×10-7～5.0×10-4mol·L-1范围内有良好的线性关系,线性方程为ip=0.1767 0.1055 lg(c×107),相关系数为0.9972,检出限为1.1×10-8mol·L-1.用该法测定了合成水样中的镉离子含量,回收率为98.5%～103%.     

阴极吸附溶出方波伏安法测定微量镉

研究了阴极吸附溶出方波伏安法测定微量镉的方法,该法不受共存离子镍、锌等的干扰。详细研究了阴极吸附溶出方波伏安法测定微量镉的最佳条件。在pH=4.50的0.2 mol.L-1HAc—NaAc缓冲体系中,Cd2 —XO配合物在汞膜电极上于-0.68 V(Vs.Ag/AgCl)处产生一灵敏的阴极吸附溶出方波伏安峰,灵敏度高,波形好。峰电流Ip与Cd2 浓度在1.5×10-7~5.0×10-6mol.L-1范围内呈良好的线性关系,相关系数为0.997 6,其检测下限为5.0×10-8mol.L-1。将该法用于水中微量镉的测定,结果较好。     

DL-精氨酸/石墨烯修饰电极测定铅

用循环伏安法制备DL-精氨酸/石墨烯修饰玻碳电极,研究金属铅在修饰电极上的电化学行为。在0.1 mol/L pH=4.5的NaAc-HAc缓冲液中,以DL-精氨酸/石墨烯修饰电极作为工作电极,用循环伏安法测定-1.0~1.0 V处的溶出峰电流。实验结果显示:铅的浓度与溶出峰电流具有良好的线性关系,范围是3.0×10-9~9.0×10-7mol/L,检测限为1.0×10-10mol/L,用于测定金属结果满意。     

Nafion/MWCNT修饰玻碳电极伏安法测定痕量镉

用阳极溶出伏安法考察了Nation/多壁碳纳米管(MWCNT)复合修饰玻碳电极测量痕量镉的优化条件.在pH 5.8的磷酸盐缓冲液中,当Cd2 在Nation/MWCNT修饰电极表面富集时间为3 min,电位扫速为150 mV/s时,该修饰电极在伏安图上能出现一灵敏的氧化峰,峰电位约为-0.78 V.利用该峰可以进行痕量镉的检测,峰电流与Cd2 浓度在8.0×10-10-1.0×10-8mol/L.的范围内呈良好线性关系,相关系数为0.999,检出限可达100×10-11mol/L(S/N=3).该法用于人发样品中镉含量的测定,平均回收率为98.7%.     

芦丁修饰碳糊电极吸附溶出伏安法测定铅

制作了用芦丁作修饰剂的修饰碳糊电极。用此电极为工作电极,在0.1mol/L甲酸 甲酸盐缓冲溶液(pH=3.0)中,于-0.90V(vs.SCE)处搅拌富集,Pb2+与碳糊修饰电极表面的芦丁形成电活性络合物而吸附富集于表面,静止20s后阳极化扫描,于-0.44V左右获得一灵敏的铅阳极溶出峰。详细研究了测定Pb2+的条件,如底液的pH值,富集电位,富集时间,扫描速度和修饰剂的用量等。在最优化的实验条件下,该修饰电极测定Pb2+的线性范围为(5.0×10-7～2.0×10-9)mol/L,检出限为9.0×10-10mol/L。用该修饰电极测定了实际水样中的Pb2+,平均回收率为101%。     

石墨烯修饰玻碳电极同时测定邻苯二酚和对苯二酚

将自制的氧化石墨烯以滴涂法修饰在玻碳电极表面,通过电化学还原方法制备得到石墨烯修饰电极。考察了电化学还原条件、修饰量以及底液等对修饰电极的影响。修饰电极对对苯二酚和邻苯二酚的电化学氧化还原表现出很高的电催化能力和分离能力。在0.1 mol/L磷酸盐缓冲溶液(pH7.0)作为支持电解质,利用循环伏安法和微分脉冲伏安法,石墨烯修饰电极可同时检测邻苯二酚和对苯二酚,二者的微分脉冲伏安响应与浓度在8.0×10-6～1.2×10-4mol/L和3.0×10-6～1.0×10-4mol/L范围呈良好的线性关系,检出限分别为1.2×10-6mol/L及3.7×10-7mol/L(3倍噪音法)。     

邻对苯二酚在石墨烯-聚噻吩复合膜修饰电极上的电化学行为及测定

研制了一种新型的石墨烯/聚噻吩复合膜修饰玻碳电极(GR/PTh/GCE),在0.100 mol/L的柠檬酸-磷酸氢二钠缓冲溶液中(pH 7.0),利用循环伏安法(CV)研究了该修饰电极对邻苯二酚(CC)和对苯二酚(HQ)的电催化作用,同时利用差分脉冲溶出伏安法(DPSV)测定邻苯二酚和对苯二酚的含量,线性范围为1.00×10-6～4.00×10-4mol/L,检出限为1.50×10-7 mol/L,并应用于模拟废水中邻苯二酚和对苯二酚的测定,回收率分别为98.0％～103.0％、96.0％～104.O％,效果良好.     

多壁碳纳米管修饰电极对Cu2+的检测研究

在实验中制备了多壁碳纳米管修饰玻碳电极,并用阳极溶出伏安法研究铜离子的检测。结果表明,在0.6 mol·L^-1硫酸溶液中,于-0.7 V(vs SCE)处富集420 s后进行阳极溶出伏安扫描,测得Cu²⁺浓度在2.0×10^-7～2.8×10^-5 mol·L^-1范围内与峰电流成线性关系,其线性方程为I_p(A)=-267.96c-0.0002,检测限为5.4×10^-8 mol·L^-1。加标回收实验研究表明,该修饰电极用阳极溶出伏安法测定痕量铜的方法可行。     

乙二胺四乙酸二钠修饰碳糊电极测定铜(Ⅱ)

制备了乙二胺四乙酸二钠(EDTA)修饰碳糊电极并研究了铜在该电极上的阳极溶出伏安行为,提出了一种测定铜的新方法。实验发现,在pH=3.6的醋酸钠-醋酸缓冲溶液中,铜离子于-500 mV(vs.SCE)处被吸附还原,富集在该修饰电极表面。从-150 mV以120 mV/s的速率正向扫描至200 mV,铜在约90 mV处出现一灵敏的阳极溶出峰。峰电流与铜的浓度在1.0×10-8~2.0×10-6mol/L范围内呈良好的线性关系,检出限为1.0×10-9mol/L。并进行了回收率测试,回收率为93%~105%,相对标准偏差小于4%。     

Percolation effects in functionally graded SOFC electrodes

A solid oxide fuel cell (SOFC) composite electrode exhibits a superior performance compared to a single phase electrode since the electrochemically active zone is spread into its volume. A functionally graded composite electrode consisting of monosized spherical electrocatalyst and electrolyte particles is sintered numerically by the discrete element method (DEM). The electrochemical performance is evaluated by a resistance network approach using Kirchhoff's current law. In the network discretization each contact between two particles is substituted by a bond resistance defined by contact size and the type of materials in contact.The graded electrode is optimized by varying its composition at the electrolyte/electrode interface and the degree to which the composition decreases linearly towards the current collector/electrode interface. Regarding its electrochemical activity, the graded electrode does not perform significantly better than an optimized uniformly randomly mixed composite electrode but percolation of the graded electrode is improved. In order to demonstrate the importance of percolation effects, a novel better performing electrode is developed which contains electronically conducting particle chains arranged within a random packing of ionically conducting particles.     

钛基体二氧化铅电极制备改性方法研究进展

寻找稳定性能好及催化性能高的阳极材料是推广电化学水处理技术的关键。钛基体二氧化铅电极在稳定性及催化性方面具有明显优势,但仍存在不少问题。对钛基体二氧化铅电极进行改性以提高其稳定性及催化性成为目前氧化物阳极材料研究中的热点之一。本文主要综述二氧化铅的性质、钛基体二氧化铅电极结构以及针对电极不同结构层进行的技术改性方法;重点阐述采用改性钛材料作为电极基体、在二氧化铅表层与钛基体之间引入中间层、采用杂质元素与杂质颗粒进行掺杂和电极制备方法改进及优化;并指出钛基体二氧化铅电极的发展趋势在于：电极组成形式与成分的多样化,开发新的电极制备技术,以及研究二氧化铅电极的失效机理以便指导电极后续的改性工作等。     

POROUS ELECTRODE THEORY ANALYSIS OF A VARIABLE-DEPTH, FLOW-BY POROUS ELECTRODE

A comparison has been made between a variable-depth and constant-depth, flow-by porous electrode in which a single metal ion deposition occurs in parallel with proton reduction. Porous-electrode theory was applied lo calculate the reactor's performance under limiting-current and below limiting-current conditions. The thickness profile of the variable-depth electrode was calculated—as first suggested by Kreysa—by constraining the solution phase potential drop across the electrode to remain constant and independent of streamwise position. For each reactor configuration, identical electrolyte and electrode properties, processing rate, reactant conversion, and inlet thickness were assumed. Under this basis of comparison, the results show: the space-time yield of the constant-depth electrode is larger, but the variable-depth electrode better utilizes the separator's and counterelectrode's surface area; the power requirement of the variable-depth electrode is greater; and, the current efficiency is parameter dependent, but for the majority of the situations likely to be found in wastewater processing, that in the constant-depth electrode is slightly higher. A simple capital-cost analysis shows that the variable-depth electrode may be less expensive if the costs associated with the separator and counterelectrode are greater than those which scale with the electrode volume.     

POROUS ELECTRODE THEORY ANALYSIS OF A VARIABLE-DEPTH, FLOW-BY POROUS ELECTRODE

A comparison has been made between a variable-depth and constant-depth, flow-by porous electrode in which a single metal ion deposition occurs in parallel with proton reduction. Porous-electrode theory was applied to calculate the reactor's performance under limiting-current and below limiting-current conditions. The thickness profile of the variable-depth electrode was calculated—as first suggested by Kreysa—by constraining the solution phase potential drop across the electrode to remain constant and independent of streamwise position. For each reactor configuration, identical electrolyte and electrode properties, processing rate, reactant conversion, and inlet thickness were assumed. Under this basis of comparison, the results show: the space-time yield of the constant-depth electrode is larger, but the variable-depth electrode better utilizes the separator's and counterelectrode's surface area; the power requirement of the variable-depth electrode is greater; and, the current efficiency is parameter dependent, but for the majority of the situations likely to be found in wastewater processing, that in the constant-depth electrode is slightly higher. A simple capital-cost analysis shows that the variable-depth electrode may be less expensive if the costs associated with the separator and counterelectrode are greater than those which scale with the electrode volume.     

自焙电极特性及在制磷电炉上的应用(待续)

自焙电极是大型制磷电炉的关键技术之一 ,单位产品的电极消耗费用比预烧结电极的低得多。介绍了国内外制磷电炉选择电极类型的简况 ,分析了电极糊在烧结过程的物态变化以及制磷电炉对电极糊的要求 ,根据降低电炉制磷的生产成本及国内制磷电炉使用自焙电极的经验 ,建议在制磷电炉中推广应用。     

Ozone Generator with Cylindrical Type of Rotating Electrode

An ozone generator using a rotating electrode to improve ozone generation efficiency is proposed. The ozone generator electrode unit consists of a rotating electrode and fixed electrode. The rotating electrode has the grounded 36 pieces of tungsten wires fixed in parallel to the rotation axis on the rotating cylinder surface. A dielectric electrode is used as a fixed electrode located on the inside of the tube of the electrode unit. The width of the apparent discharge gap is 1mm. Alternating current with a frequency of 50 Hz is applied to the electrode unit. The rotation speed can be adjusted from 0 rpm to 1200 rpm by a variable speed motor. Oxygen gas is used as the material gas. Higher ozone concentration and higher ozone generation efficiency are obtained compared with that when the rotation speed is 0 rpm. The gas temperature is measured at the inlet and outlet of the ozone generator, and the rotation speed for the cooling effect is most effective at about 500 rpm. The maximum generation efficiency is estimated to be 61 g/kWh at 800 rpm, and this value is twice as large as in the case of 0 rpm.     

CdS/TiO_2电极的制备及其光电性能的研究

采用电化学沉积方法制备CdS/TiO2电极并研究其光电催化性能,比较了不同电压、反应物浓度、不同电解质等条件下CdS/TiO2电极所显示的光电性能。另外,将CdS/TiO2与CdS/Ti电极进行光电性能比较,得出了在相同沉积时间下CdS/TiO2电极的光电性能比CdS/Ti电极稳定,产生的光电流略有提高的结论,在多数方面都优于CdS/Ti电极。     

电位滴定法测定异辛酸钴中的钴含量

本文提出了一个测定钴的新方法。以钴标准溶液为滴定剂 ,铂电极为指示电极 ,甘汞电极作为参比电极 ,利用电位的突变来指示终点。具有灵敏、准确、快速等特点     

POROUS ELECTRODE THEORY ANALYSIS OF A VARIABLE-DEPTH,FLOW-BY POROUS ELECTRODE

A comparison has been made between a variable-depth and constant-depth, flow-by porous electrode in which a single metal ion deposition occurs in parallel with proton reduction. Porous-electrode theory was applied to calculate the reactor's performance under limiting-current and below limiting-current conditions. The thickness profile of the variable-depth electrode was calculated—as first suggested by Kreysa—by constraining the solution phase potential drop across the electrode to remain constant and independent of streamwise position. For each reactor configuration, identical electrolyte and electrode properties, processing rate, reactant conversion, and inlet thickness were assumed. Under this basis of comparison, the results show: the space-time yield of the constant-depth electrode is larger, but the variable-depth electrode better utilizes the separator's and counterelectrode's surface area; the power requirement of the variable-depth electrode is greater; and, the current efficiency is parameter dependent, but for the majority of the situations likely to be found in wastewater processing, that in the constant-depth electrode is slightly higher. A simple capital-cost analysis shows that the variable-depth electrode may be less expensive if the costs associated with the separator and counterelectrode are greater than those which scale with the electrode volume.     

Potential and current distribution on the surface of a hydrogen gas diffusion anode

The current and potential distribution for a hydrogen gas-diffusion disc electrode with a relatively high ohmic resistance are investigated. A theoretical model for these distributions is presented. Potential differences between the edge of the electrode and points on the electrode surface have been measured for a hydrogen gas-diffusion electrode loaded with various total currents. From the results it is concluded that the proposed model is very useful to obtain the potential and the current density distribution along a hydrogen-gas diffusion disc electrode. Moreover, the allowable size of cylindrical holes in a perforated plate placed against the rear of the gas diffusion electrode for its current supply, can be calculated to achieve a reasonably uniform current distribution along the gas-diffusion electrode.