离子膜稳定运行的影响因素分析

分析盐水质量、阴极液NaOH浓度、阳极液NaCl浓度、电流密度、阳极液pH值、电解液温度和流量、电解槽压力和压差、开停车及伴生水摩尔量不符合运行指标时,会造成离子膜起泡、针孔,阴、阳极涂层损坏。结合济宁中银电化有限公司的运行实际,强调分析化验的重要性。     

离子膜电解单元槽电压升高的原因分析

从进槽盐水、阴极液浓度、阳极液浓度、电流密度、电解液温度等操作指标以及电槽结构阳极、阴极等角度分析了引起离子膜电解槽电压升高的原因和降低槽电压应采取的措施：严格控制进槽盐水、阴极液、阳极液浓度、电流密度、电解液温度、进料纯水质量等操作指标在规定范围之内；保持电槽不能开焊；对电槽加酸，膜漏要及时换膜，减少电槽停车次数；清洗阴极表面时，防止把活性涂层刷掉，阴极管路、设备要选用高质量材质，以避免铁在阴极表面沉积。     

影响离子膜电解液质量因素分析

从离子交换膜的特性,阴极液浓度,阳极液浓度,电流密度,槽温,阳极室压力等方面分析了影响离子膜电解液质量的因素。     

加强管理保证电槽平稳运行

介绍了4万t／a离子膜运行1年多的倩况，指出影响离子膜电槽运行的主要因素有盐水质量、阳极液PH值、电流密度、电槽温度、阳极液浓度、阴极液浓度和槽压差等，认为只有严格管理，遵守操作方法，才能保证离子膜电槽平稳运行。     

浅议影响离子膜电解槽电流效率的因素

保持最佳的离子膜电解工艺操作条件是离子膜电解槽的操作关键,它能使离子膜长期稳定地保持较高的电流效率和较低的槽电压,进而稳定直流电耗,延长离子膜的使用寿命。本文详细分析了影响离子膜电解槽电流效率的因素,认为电解槽在运行过程中,要保持高的电流效率应做到:高质量的入槽盐水;适宜的阴极液浓度、阳极液浓度和适宜的电流密度;严格控制阳极液PH值;保持适宜的电解槽温度、电解液流量和稳定的高质量的无离子水供应。     

影响离子膜电解槽槽电压的因素

阐述了离子膜电解槽操作温度、电流密度、电解液流量、阴极液质量分数、阳极液质量分数、阳极液ｐＨ值、阳极液中金属离子以及阴极材料等九方面对电解槽电压的影响。     

离子膜装置电流效率下降幅度的改善

通过影响离子膜电流效率的主要因素、离子膜装置存在的问题，来分析离子膜装置电流效率下降幅度改善的措施，主要有：优化盐水质量、开停车次数改善、阳极液中氢氧化钠浓度、氯化钠浓度的控制改善、严格工艺管理和工艺操作等几种有效措施。     

离子膜电解工艺中电流效率的影响因素

简要分析了离子膜电解过程中影响离子膜电流效率的影响因素,提出应选择适宜的电流密度,严格控制盐水中杂质离子的含量,阴、阳极有稳定的浓度及电解温度,严格控制阳极的p H值,根据电解槽出口产品质量调整电解液和纯水流量,从而延长离子膜的使用寿命,保持高电流效率。     

离子膜鼓泡的原因及预防措施

分析了江汉油田盐化工总厂离子膜鼓泡原因,指出进电解槽阳极液浓度过低、电解槽长时间不排液、电流分布不均匀、停车后的“电池效应”及未及时降低槽温等造成离子膜鼓泡。针对这些问题,采取相应措施,消除鼓泡因素,保证生产顺利进行。     

离子交换膜的维护

介绍离子交换膜的工况。分析盐水中的杂质，阴、阳极液浓度变化，温度。压力对离子交换膜性能和寿命的影响原理。提出维护离子膜的方法有：平稳运行，减少开、停车次数和增加预防控制措施。修复离子膜的方法有停车时循环阳极液、用纯水清洗离子膜或根据实际情况改变运行状态，如离子交换膜受Ca^2 、Mg^2 轻微污染时，先停车再启动；受中度污染时可将阴极液质量分数从32％调整到33％，或将阳极液质量浓度从190g／L升至200g／L，或同时调整阴极液、阳极液浓度。     

Chlorate Transport through Ion-Exchange Membranes

A laboratory scale chlor-alkali membrane cell was used to measure the chlorate concentration in the outlet NaOH as a function of current density, temperature, film thickness, brine strength and various membrane properties. The chlorate concentration in the NaOH increased with increasing anolyte chlorate spiking level and temperature and decreasing current density and carboxylate film thickness and was strongly dependent on the type of ion-exchange membrane used. In addition, the presence or absence of sacrificial fibers in the membrane did not measurably influence the resultant chlorate concentration. Chlorate ions were transported to the catholyte side by diffusion and electroosmotic convection and transported toward the anolyte side by migration. This balance between the three modes of transport dictates the chlorate concentration present in the NaOH product.     

离子膜电解槽加酸探讨

采用向离子膜电解槽阳极液中加盐酸的方法可以提高阳极电流效率,同时可以降低氯中含氧和阳极液氯酸盐含量。以蓝星北化机厂家NBH-2.7型自然循环离子膜电解槽为例,阐述了阳极液加酸的作用、加酸点、加酸量控制和应注意的问题。     

比值控制方法在离子膜电解工艺中的应用

介绍了在离子膜电解工艺中氯氢总管压力、电解槽阳极液流量、电解槽阳极淡盐水流量、电解槽加盐酸流量及盐酸浓度、阴极加纯水量等的比值控制方法。     

离子膜电解槽运行中几个常见问题的简述

在离子膜法电解生产氮碱过程中，影响电槽运行的因素有：进槽盐水质量、高纯盐酸质量、去离子水纯度、阴、阳极液浓度、电槽温度、压差波动等。只有严格工艺管理，保证工艺指标，才能使电解装置长期、稳定、高效运行。     

Ion transport in a two membrane electrowinning cell for the production of hydrochloric acid

A three-compartment electrowinning cell has been evaluated for the regeneration of HCl from metal chloride catholyte. By segregating the catholyte with an anion exchange membrane, and the anolyte with a cation exchange membrane from the middle electrolyte(ampholyte) compartment, HCl could be produced in the ampholyte electrochemically up to one molality. The anolyte consisted of sulphuric acid. Successful operation of such a double membrane cell depends on controlling ion transport through the membrane, especially chloride migration into the anolyte. Results of electrowinning and self-diffusion experiments for three types of cation exchange membrane are presented and discussed.     

Electrochemical membrane reactor: In situ separation and recovery of chromic acid and metal ions

An electrochemical membrane reactor with three compartments (anolyte, catholyte and central compartment) based on in-house-prepared cation- and anion-exchange membrane was developed to achieve in situ separation and recovery of chromic acid and metal ions. The physicochemical and electrochemical properties of the ion-exchange membrane under standard operating conditions reveal its suitability for the proposed reactor. Experiments using synthetic solutions of chromate and dichromate of different concentrations were carried out to study the feasibility of the process. Electrochemical reactions occurring at the cathode and anode under operating conditions are proposed. It was observed that metal ion migrated through the cation-exchange membrane from central compartment to catholyte and OH⁻ formation at the cathode leads to the formation of metal hydroxide. Simultaneously, chromate ion migrated through the anion-exchange membrane from central compartment to the anolyte and formed chromic acid by combining H⁺ produced their by oxidative water splitting. Thus a continuous decay in the concentration of chromate and metal ion was observed in the central compartment, which was recovered separately in the anolyte and catholyte, respectively, from their mixed solution. This process was completely optimized in terms of operating conditions such as initial concentration of chromate and metal ions in the central compartment, the applied cell voltage, chromate and metal ion flux, recovery percentage, energy consumption, and current efficiency. It was concluded that chromic acid and metal ions can be recovered efficiently from their mixed solution leaving behind the uncharged organics and can be reused as their corresponding acid and base apart from the purifying water for further applications.     

Effect of silicate on the membrane-type chlor-alkali cell

The effect of silicate in the electrolyte solution in a chlor-alkali cell on a fluorocarbon ionomer, Nafion^® 901, was studied. Calcium silicate precipitated and damaged the membrane during electrolysis when the anolyte and/or the catholyte was contaminated with Ca²⁺ and Mg²⁺. The service lifetime of the membrane was thus shortened greatly.