离子膜电解槽经济运行指标探索

通过分析出槽碱浓度、出槽盐水浓度、阳极液pH值、槽温、阴阳极压力和氯氢压差、电流密度、阴阳极循环量、盐水质量对槽电压和电流效率的影响,利用控制变量法对各个影响因素进行测试,总结离子膜电解槽经济运行指标,实现降本增效.     

零极距电解槽初始开车的运行情况

分析了零极距电解槽初始开车后的运行状况,讨论了影响单元槽电压、电流效率及电耗的因素。     

石棉隔膜的基本特性和研制

一引言氯碱电解槽的特性用能耗表示:E=(V/CE)×75600 其中:E是能耗(KW·h/吨·氯) V是槽电压(伏特) CE是电流效率(％) 常数75600等于在100％电流效率时,放出1吨氯气所需要的千安小时数的100倍。公式表明:通过降低槽电压和增加电流效率,能够改善电槽的性能,得到较低的能耗。在隔膜槽中,槽电压和电流效率取决于电槽结构、电极材料、电解条件和隔膜性质。本文论述石棉隔膜性能和电槽特性之间的关系以及改进隔膜性能使得到较佳电槽特性的问题。二隔膜性能对槽电压的影响在隔膜槽中常用的电流密度值25A/dm~2附近,槽电压V和电流密度I之间存在一个线性关系:V=2.36 KI。     

高电流密度离子膜电解槽膜极距试验总结

分析槽电压的影响因素,从理论上说明极间距近,可以大幅度降低槽电压.高电流密度离子膜电解槽部分单元槽的膜极距改造试验,说明改造1台电解槽可节约电费421 478.64 元/a,提出了在此类电解槽上进行大规模改造的建议.     

电沉积处理络合-超滤过程中含镍浓缩液

在络合-超滤处理含镍废水并得到镍离子质量浓度为418 mg/L浓缩液的基础上,考察了电沉积法处理含镍浓缩液过程中电流密度、初始pH、电解时间、温度、极距、搅拌等参数对电流效率和镍回收率的影响。结果表明:当电流密度、电解时间增加时,电流效率随之下降,而镍回收率增大;当pH、极距增大时,电流效率和镍回收率均先增大后减小;温度升高、低速搅拌均可提高电流密度与镍回收率。在电流密度为3.5 m A/cm~2,pH=4,温度为50℃,电解时间为130 min,极距为10 cm并加入低速搅拌的最优操作条件下,电流效率最高可达42%,镍回收率可达52%,并探讨了电沉积机理。     

氯工程BiTAC888电解槽膜极距改造和整体换膜后的效果评价及后期改善思路

对氯工程自然循环电解槽膜极距改造及整体换膜后,单元槽电压下降约240 m V,电耗下降约265k W·h/t,电流效率提高2.3%。介绍改造后的操作变化,对装置后期的稳定运行提出改善思路。     

电解法回收废盐酸实验研究

采用滤压式隔膜电解槽对低质量分数废盐酸进行电解回收利用实验研究,实验分别讨论了电流密度、电解液流量、温度和HCl、NaCl混合电解液质量分数对槽电压和电流效率的影响,通过实验得出,电流效率影响最显著的因素是电解液流量,槽电压的最主要影响因素是电流密度。最佳工艺水平为:流量12 mL/min,电流密度0.2 A/cm2,电解温度50℃,电解液为质量分数7%HCl与NaCl混合液。验证实验得出电流效率为95.11%,槽电压为4.1 V。     

Research on waste hydrochloric acid recvcling by electrolysis

采用滤压式隔膜电解槽对低质量分数废盐酸进行电解回收利用实验研究,实验分别讨论了电流密度、电解液流量、温度和HCl、NaCl混合电解液质量分数对槽电压和电流效率的影响,通过实验得出,电流效率影响最显著的因素是电解液流量,槽电压的最主要影响因素是电流密度.最佳工艺水平为:流量12 mL/min,电流密度0.2 A/cm2,电解温度50℃,电解液为质量分数7％ HCl与NaCl混合液.验证实验得出电流效率为95.11％,槽电压为4.1V.     

氯碱工业离子膜电解槽内气液相返混研究

利用计算流体力学软件对零极距自然循环离子膜电解槽内气液相停留时间分布进行了研究,考察了电流密度对电解槽内气液相返混程度的影响。结果表明,随着电流密度增大,电解槽内液相返混程度降低;当电流密度为5 kA/m~2时,电解槽内液相的多釜串联模型参数为2.782,该值可为高电流密度电解槽设计提供参考。电解槽内气相返混随着电流密度增加先增大后减小,在电流密度为6 kA/m~2时,返混程度达到最大。     

离子膜电解槽膜极距改造化学清洗技术应用

介绍高电流密度自然循环复极式离子膜电解槽改造为膜极距电解槽过程中,对阴极液循环系统进行化学清洗,消除铁离子富集在阴极网造成的槽电压升高。     

Temperature dependence of the electrochemical corrosion characteristics of carbon steel in a salty soil

The electrochemical corrosion characteristics of carbon steel in a salty soil at different temperatures were studied by measurements and analyses of potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance spectroscopy. The results showed that the mass-transfer of dissolved oxygen plays an essential role in carbon steel corrosion, and the whole corrosion process is mix-controlled by both activation and mass-transfer steps. Passivity can be developed on carbon steel in the soil at low temperatures. With the increase of temperature, the passive current density increases and the passive potential range decreases. When temperature is elevated to a certain value, 50 °C in this system, passivity cannot be maintained and the steel is dominated by an active dissolution status. Anodic Tafel slope decreases continuously with the increase in temperature, which is mainly due to the enhanced electrode reaction rate at an elevated temperature. Simultaneously, cathodic Tafel slope increases with temperature continuously due to the decrease of the solubility of dissolved oxygen in soil. Since the diffusion activation energy is generally much smaller than the reaction activation energy, the effect of temperature on diffusion is far less than that on electrode reaction rate.     

Bifunctional electrodes for an integrated water-electrolysis and hydrogen-oxygen fuel cell with a solid polymer electrolyte

An alternative concept of an integrated water electrolysis/hydrogen-hydrogen fuel cell using metal electrocatalysts and a solid polymer electrolyte is described. Instead of operating both electrodes as hydrogen and oxygen electrodes respectively the electrodes are used as oxidation and reduction electrodes in both modes of operation. A more suitable selection of electrocatalysts and an improved cell design are possible; both can increase the efficiency of the cell considerably. New results on the electrocatalytic activity of various noble-metal containing catalysts with respect to both oxygen evolution and hydrogen oxidation in a proton exchange membrane-cell at 80°C are reported. Kinetic data derived from Tafel plots of the oxygen evolution polarization curves agree closely with those of experiments with aqueous sulphuric acid electrodes. This agreement allows the determination of kinetic parameters for electrocatalysts difficult to prepare in solid smooth electrodes but easy to be made into porous deposits. Polarization curves of the hydrogen oxidation reaction clearly indicate a relative activity rating of the studied catalysts. In cycling tests the lifetime stability of the new bifunctional oxidation electrode was determined. Polarization data obtained under these conditions agree with those obtained in earlier experiments where electrodes were exposed to only one type of oxidation reaction. During a test of 10 cycles (30 min of electrolyser and 30 min of fuel cell mode each) no changes in the electrode potential were observed. With the conventional cell design employing a hydrogen and an oxygen electrode both catalyzed with platinum and a current density of 100 mA cm^–2 a storage efficiency of 50% was calculated; with the alternative concept of oxidation and reduction electrodes and selected oxidation catalysts this was improved to 57%. With further improvements these efficiencies seem possible even at current densities of 500 mA cm^–2.     

酸性镀锡液中铁杂质的影响及去除

采用赫尔槽试验,研究了在不同电流密度下,酸性镀锡液中加入三乙四胺六乙酸(TTHA)对去除Fe2 的效果和对镀层的影响;通过盐雾试验及塔菲尔曲线的测量,研究了镀层的耐蚀性能.研究结果表明:采用小电流密度和加入三乙四胺六乙酸均能有效去除酸性镀锡液中的铁杂质,消除铁杂质对镀层的影响,可获得银白色光亮镀层.本文还采用交流电桥测量微分电容曲线的方法,在滴汞电极上测定了三乙四胺六乙酸的微分电容曲线,并对三乙四胺六乙酸的作用机理进行了探讨.     

Effect of pyridine and its derivatives on the electrodeposition of nickel from aqueous sulfate solutions. Part II: Polarization behaviour

The electrochemical reactions occurring during electrodeposition of nickel from acidic sulfate solutions were examined by cyclic and linear sweep voltammetry techniques. The effect of pyridine, 2-picoline and 4-picoline on the electrode polarization behaviour and electron transfer parameter of the cathodic reduction process was also investigated. Strongest electrode polarization was seen with 4-picoline. The order of cathodic polarization was 4-picoline > 2-picoline > pyridine. Kinetic parameters such as Tafel slope, transfer coefficient and exchange current density were determined to analyse the nature of the electrode reactions. The exchange current density for nickel deposition on nickel and stainless steel substrates was in the order 4-picoline < 2-picoline < pyridine.     

不同炭材料制备的铂炭复合电极电化学参数

以乙炔黑、石墨乳、聚苯胺树脂炭和聚亚苯基树脂炭为载体。用化学吸附还原法制备了不同炭材料的铂炭复合电极，采用恒电位法测定了这些铂炭复合电极的阴极极化曲线，并在此基础上求出了复合电极的有关电化学参数，实验结果发现：不同炭材料制备的铂炭复合电极交换电流密度相差较大，在相同铂含量条件下用聚亚苯基树脂炭制备的铂炭复合电极变换电流密度为０．２６７ｍＡ．ｃｍ＾－２，而用乙炔黑制备的铂炭复合电极交换电流密度仅为０     

大电流密度下铬电极析氢行为

在电解金属铬使用的7.5~20 A/dm2的大阴极电流密度下，测定了温度30~55℃及pH为2.1~2.5条件下的硫酸铵体系中铬电极表面析氢极化曲线，探讨了大电流密度下铬电极析氢的电化学过程. 结果表明，同一电流密度下，温度升高或pH值降低，析氢电位的绝对值变小. 电解铬时十六烷基三甲基溴化铵的加入使析氢极化曲线向负方向移动，可用作阻氢剂. 加入20 mg/L的十六烷基三甲基溴化铵，电流效率提高了8.1%. 由pH=2.1时的极化曲线得到不同温度及电流密度下铬电极表面一系列析氢过电位值. pH=2.1时的极化曲线的塔菲尔直线均通过lgi为1.72、过电位为1.35 V的公共点.     

Kinetics of hydrogen evolution reaction on a stainless steel electrode

The kinetic parameters for the hydrogen evolution reaction on a stainless steel substrate have been obtained from a study of the steady-state polarization curves as well as the galvanostatic transients. The high Tafel slope obtained in the steady-state polarization measurements was ascribed to the presence of an oxide film present on the surface of the stainless steel electrode.     

PEM fuel cell reaction kinetics in the temperature range of 23-120 °C

The performance of a Nafion 112 based proton exchange membrane (PEM) fuel cell was tested at a temperature range from 23 °C to 120 °C. The fuel cell polarization curves were divided into two different ranges based on current density, namely, <0.4 A/cm² and >0.4 A/cm², respectively. These two ranges were treated separately with respect to electrode kinetics and mass transfer. In the high current density range, a linear increase in membrane electrode assembly (MEA) power density with increasing temperature was observed, indicating the advantages of high temperature operation.Simulation based on electrode reaction kinetic theory, experimental polarization curves, and measured cathodic apparent exchange current densities all gave temperature dependent apparent exchange current densities. Both the calculated partial pressures of O₂ and H₂ gas in the feed streams and the measured electrochemical Pt surface areas (EPSAs) decrease with increasing temperature. They were also used to obtain the intrinsic exchange current densities. A monotonic increase of the intrinsic exchange current densities with increasing temperature in the range of 23-120 °C was observed, suggesting that increasing the temperature does promote intrinsic kinetics of fuel cell reactions.There are two sets of cathode apparent exchange current densities obtained, one set is for the low current density range, and the other is for the high current density range. The different values of cathode current densities in the two current density ranges can be attributed to the different states of the cathode Pt catalyst surface. In the low current density range, the cathode catalyst surface is a Pt/PtO, and in the high current density range, the catalyst surface becomes pure Pt.     

苯甲醇在Cu-PTFE复合电极上的电化学氧化行为

采用复合电镀制备Cu—PTFE疏水性复合电极并应用于苯甲醇的电化学氧化的研究。实验中分别测定了极化曲线、循环伏安和交流阻抗等电化学特征参数。结果表明,苯甲醇在Cu—PTFE疏水性复合电极上的电氧化电流效率为41．8％,苯甲醛的产率为83．1％,其电化学过程可能受电荷传递和浓差扩散过程综合控制。     

锌-空气电池电解液Zn2+浓度对析氢过程的影响

水溶液体系的二次金属-空气电池通常具有安全环保的特点,但是充电过程中仍然存在析氢副反应的安全隐患。使用线性电势扫描方法、Tafel极化曲线及极限扩散电流密度参数定量分析了二次锌-空气电池体系电解液中Zn²⁺浓度对析氢反应过程的影响。结果表明,随着电解液中Zn²⁺浓度的提高,析氢过电势逐渐增大,Zn²⁺浓度在6 mol·L^-1 KOH溶液中达到0.4 mol·L^-1时,析氢过电势超过2.42 V,析氢过电势比空白溶液提高1.2 V,并且Tafel极化曲线的截距超过1.5 V,析氢电势达到超高过电势范围。此外,由Zn²⁺提供的极限扩散电流密度提高至8.9 A·cm^-2,所对应的过电势提高700 mV。研究结果对于确立二次锌-空气电池极限充电范围提供定量依据,对电池安全平稳运行具有重要价值。