离子膜性能下降因素及危害

离子膜法电解制烧碱的生产过程中，离子膜的性能相对稳定；当离子膜受到盐水杂质，机械损伤，溶胀，收缩及其它因素的影响时，均有可能导致离子膜性能的下降。分析了不同因素可能对膜造成的损伤，介绍了避免这些损伤应采取的预防措施，以及发生损伤后的处理方法。     

离子膜电解槽电流效率的影响因素

介绍离子膜电解槽中的电化学反应及电流效率的计算方法。重点分析影响电流效率的主要因素：离子交换膜的交换容量、烧碱浓度、阳极液中氯化钠浓度、电流密度、盐水中的杂质、操作温度和阳极液添加的盐酸,     

Proton exchange membrane water electrolysis at high current densities: Response time and gas-water distribution

Understanding the distribution of oxygen in proton exchange membrane water electrolysis (PEMWE) is crucial for improving electrolysis efficiency and gas removal. In this study, we developed a two-dimensional (2D) transient model that couples the Euler–Euler multiphase model with electric potential equations to investigate two-phase flow in PEMWE. Our simulation reveals that the system's response time initially decreases and then increases with current density, indicating longer response times at high current densities. Modifying the wetting properties of the porous transport layer (PTL) affects gas removal at low gas holdup, resulting in a maximum 15% decrease in gas holdup. However, at high gas holdup, the flow field in the channel predominantly governs bubble removal, making changes in PTL wetting properties less influential. With increasing gas production rate, an inverse gradient distribution of gas saturation appears, leading to uneven gas saturation and hindering efficient oxygen removal. This non-uniform gas saturation adversely affects electrolysis performance.     

离子膜电解槽阴极电流效率计算

根据离子膜电解槽的电化学原理和在阳极室中发生的化学反应,演示了阴极电流效率计算公式的推导过程。通过对阴极电流效率的计算,可以动态监控电解槽的经济运行状况,预测其运行趋势,为电解槽的检修和运行管理提供参考依据。     

离子膜碱中氯化钠的测定

介绍了用电位滴定法和分光光度法测定离子膜碱中氯化钠含量的方法,并对这２种方法的测试结果进行了比较。电位滴定法适用于常量分析,具有操作简便、分析速度快、测量结果准确等特点。     

盐水中杂质离子对离子交换膜性能影响的研究

介绍了盐水中Ca2＋、Ma2＋、SO24-、SiO23-及Fe3＋、Al3＋、Si2＋、Ti2＋、S2-等阴阳离子对离子膜表面的污染情况及这些离子对离子膜性能的影响,并提出了延长离子膜寿命的方法.     

两种不同类型高电密离子膜电解槽的运行效果

对新疆天业集团运行的两种高电流密度离子膜电解槽的结构、操作、性能等方面进行了比较。总结了运行管理经验,对存在的问题提出了解决措施。     

A study on the transport behavior of cations in ion exchange membrane electrodialysis

The permselectivities of cations in ion exchange membrane electrodialysis for NaCl-MgCl₂ and NaCl-CaCl₂ systems are investigated. The experimental results show that the permselective coefficients T^Mg_Na and T^Ca_Na decrease as the current density increases, but increase as the bulk velocity and the total equivalent concentration of diluent increases at constant temperature. It also indicates that the permselectivity is independent of the composition of diluent at constant current density, temperature, flow rate and total equivalent concentration of diluent. The correlation of experimental results shows that the empirical relation between permselective coefficient and Stanton number St can be expressed by the following equations: T^Mg_Na = 1.527 St^-0.51 as 0.23 × 10^-3 < St < 0.9 × 10^-3 and T^Mg_Na = 1.05 as St > 0.9 × 10^-3 for NaCl-MgCl₂, system; and T^Ca_Na= 1.412 St^-0.403 as 0.4 × 10^-3 < St < 2 × l0^-3 and T^Mg_Na = 1.185 as St > 2 × 10^-3 for NaCl-CaC1₂ system. The result also indicates that the permselective coefficient T^B_A decreases and approaches to the value of the ratio of the ionic mobility U_B/U_A as Stanton number increases.     

概述离子交换膜的发展及前景应用

离子交换膜因其在节能、环保方面的巨大优势,已经发展为未来研究的主要方向。离子交换膜的分类方法已经完善,但在制备方法、改性以及应用方面的研究一直是研究的重点方向,对阴离子交换膜、阳离子交换膜及其制备过程、表面改性和掺混改性过程的研究具有巨大经济价值,离子交换膜在水处理、电渗析和冶金方面的应用可以极大的节约能源,在环境保护方面也具有巨大应用前景。     

Modification of transport properties of ion exchange membranes,XIII. Surface-modified cation exchange membranes prepared from polyamines and a copolymer membrane containing p-stryenesulfonyl chloride

A membrane precursor was prepared by the copolymerization of p-styrenesulfonyl chloride and divinylbenzene in the presence of a poly(vinyl chloride) supported cloth. The surface of the membrane was treated with various amines, and then the sulfonyl chloride groups in the internal part of the membrane were hydrolyzed with an aqueous sodium hydroxide solution in organic methanol or acetone solvent. Hydrolysis conditions were examined for the introduction of the sulfonic acid groups. The membrane modified by ethylenediamine exhibited slightly bipolar properties during the electrodialysis of seawater. Surface-modified membranes using tetraethylenepentamine exhibited excellent monovalent cation permselectivity, low membrane electric resistance, and long performance durability during the electrodialysis of seawater.     

浅谈工艺条件对离子膜电流效率的影响

从工艺角度出发,详细论述了工艺条件对离子膜烧碱电流效率的影响,从而强调了创造良好的工艺环境是提高电流效率、延长膜的寿命的重要手段。     

Water transport in ion exchange membranes

Water transport across ion exchange membranes has been studied experimentally. Water transference numbers were obtained from streaming potential measurements for cation and anion exchange membranes. At low salt concentration the water transference number reaches a limiting value which for the cation exchange membranes seems to be closely correlated with the cation—water friction in infinite dilute solutions.The observed water transference number for a given anion exchange membrane does not seem to be much dependent on the type of coion even at concentrations where the membrane is no longer perfectly permselective.     

Transient behaviour of porous electrodes with high exchange current densities

A theoretical analysis of the non-steady-state reaction distribution in a porous electrode with a high exchange current density is made by application of a simplified macrohomogeneous model for porous electrodes. The dimensionless transfer current for short times is given as an expansion in time, and two terms in a moderate time solution are also presented. At moderate times the current is split into time-dependent and time-independent parts, but this distinction is not apparent in the short time solution. For the limiting case of reversible kinetics, the analysis specifies the fraction of the superficial current density that will be distributed through the electrode. Treatments for the PbO₂ and LiAl electrodes are presented as examples.     

离子交换膜选择透过机理的研究进展

综述了近年来国内外离子交换膜选择透过机理的研究进展,指出了研究离子选择透过性的目的,详细介绍了唐南平衡理论,双电层理论和空穴传递双电层理论及各理论优势和存在的问题,探讨了膜微观结构与离子在膜相中传输机制。并讨论了电流密度、膜溶液边界条件以及离子自身性质对膜选择透过性的影响。并且提出选择透过机理的未来研究方向是结合试验进一步优化离子传输机制模型,并采用仿真工具模拟传输过程,提高模型的普适性。这有助于分析离子在膜中传递机理,并为膜制造和应用工艺提供理论指导。     

Active transport membrane for chlorine ion

A specific functional group that could interact with ions was introduced in a synthetic membrane to achieve an active transport of ions. One way to synthesize the active transport membrane was to introduce a functional group which has a tautomerism upon pH changes in an aqueous solution. A polymer having pendent N-hydroxyethyl amide groups was synthesized to form a membrane, and the membrane was fixed in a cell as a partition film, in which one side of the solution was adjusted to be acidic and the other side basic. It was then possible to transport chlorine ion through the membrane owing to the carrier functions caused by tautomerism of the N-hydroxyethyl amide group from the acidic to the basic sides. The transport of the chlorine ion was not dependent on diffusion control.     

Effect of functional group of ferrocene redox substance on the transport properties of newly designed ion exchange membrane prepared from polymer gel

A different newly designed cationic exchange polymer membrane and anionic exchange polymer membrane were introduced, and also the transport properties of these polymeric membranes were investigated in this study. The transport properties of these polymer membranes in contact with ferrocene redox derivatives were estimated by using electrochemical techniques such as cyclicvoltammetry, chronopotentiometry, and chronoamperometry techniques, respectively. The used ferrocene redox substances, which have different functional groups, were (Ferrocenylmethyl) trimethylamonium iodide, FcMA, Ferrocenedimethanol, FcDM, and Ferrocene carboxylic acid, FcCA. It indicated that the performance of a membrane depended on the content of polymer gel, anionic exchange polymer site (20 wt % and 50 wt %) or cationic polymer exchange site (20 wt % and 50 wt %), and the efficiency of the functional groups of cationic and anionic exchange polymer site as well. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A mathematical model of multiple ion transport across an ion-selective membrane under current load conditions

A macrohomogeneous mathematical model of the simultaneous transport of multiple ions across an ion exchange membrane based on the Nernst–Planck equation was developed. Schlögl's equation of motion was used to evaluate the convective term of the mass-transfer inside the membrane. The model accounts for the external diffusion of the ions through the Nernst diffusion layer to the phase boundary on both sides of the membrane. Donnan equilibrium is used to describe the potential and the concentration discontinuity on the membrane-solution interface. The results document the importance of the external diffusion layers for ion transport across the membrane.