离子交换膜间水的电离及其应用

本文通过分析纯水的电离,讨论了普通电渗析(ED)和填充床电渗析(EDI)中水的电离现象及其相关 机理。EDI过程中水电离产生的H+和OH-离子可以自再生离子交换树脂。文中简单介绍了已得到产业化的EDI 技术和正在推广中的离子交换树脂的电再生技术。     

连续电再生离子交换原理探讨

连续电再生离子交换系统(EDI)将电渗析技术和离子交换技术结合起来,无需酸、碱再生。其工作原理是系统中阴、阳离子交换树脂对水中离子的吸附交换、在电场作用下离子的定向迁移以及离子交换树脂的平衡再生。     

离子交换树脂电再生实验研究

引　言针对目前离子交换树脂酸碱再生工艺中再生药剂利用率低、再生操作步骤繁多、大量废酸碱液的排放对环境造成污染的弊病 ,借助电渗析概念提出了一种新的离子交换树脂再生方法———电再生 ,即利用水电离出的H+和OH- 离子分别再生失效的阳、阴离子交换树脂 .本实验采用单级三隔室离子交换树脂再生装置对电再生进行了研究 .1　混床树脂的电再生实验关于混床树脂电再生 ,人们已经进行了广泛的研究[1～ 6 ] .所谓电再生实质是填充床电渗析法 ,即去离子 (EDI)净水技术 .它的进水条件苛刻 ,要求反渗透处理后出水 ,填充树脂属于再生后树脂 .…     

发电用连续电去离子膜堆及系统设计创新工艺的探讨

本文通过薄室和厚室制造工艺的比较，概述连续电去离子过程的发展过程，并提出一种创新工艺，用该工艺证实其去离子效率，可与化学再生混床离子交换相媲美。连续电去离子(CEDI，即EDI)是用离子交换膜、电活性介质(通常为离子交换树脂)和直流电势，除去水中已电离的或可电离的物质迁移的过程。为降低费用，同时为提高去离子程度，这一过程自从20世纪80年代末得到产业化以来又得到不断地改进。本文的目的是回顾过去13年的某些进展，并介绍与数年经验相结合的一种创新工艺。     

EDI集成膜技术低成本制超纯水

日前在南开大学了解到。由该校研制成功的吨级规模工业电去离子技术（EDI）制水装置技术已成熟,性能达到国外技术水平．而装置成本却大大降低,使EDI技术广泛应用成为可能。据介绍．EDI技术是国外上世纪90年代才真正成熟的第四代超纯水生产技术。该技术集离子交换和电渗析技术两者的优点于一体,树脂用量极少且自动获得再生,既克服了电渗析和反渗透不能直接制取超纯水的弱点,又避免了使用酸碱再生离子交换树脂。整个过程相当于连续获得再生的混床离子交换。EDI装置无废酸废碱排放,其本身的水利用率最高可达98％。     

电去离子技术在水处理中的应用

电去离子是一种将电渗析与离子交换有机结合形成的膜分离技术,它结合了电渗析连续脱盐和树脂深度净化的特点,并克服了这两种分离技术原有的缺点,具有显著的经济效益、社会效益和环境效益.介绍了EDI技术的去离子原理,回顾了EDI技术的发展历程及其在水处理中的应用现状.     

混床离子交换树脂电再生技术

用H2O分子电离所产生的H＋和OH-离子,用水这一再生剂,代替酸碱再生失效离子交换树脂的体外电再生技术,使离子交换水处理变为一种绿色环保水处理技术。从电再生系统、原理、验证和实验及工程应用等几方面,介绍了这项高科技创新技术。     

填充床电渗析器制备纯水的研究

本文介绍了离子交换树脂在填充床电渗析器中的脱盐及电再生机理，实验研究了一价离子及二价离子在设备内的操作参数。一价离子与二价离子相比，树脂使用周期长，操作范围宽，对于一价离子，树脂可在低电压下（〈２５Ｖ）再生，在较高电压下（〉２５Ｖ），树脂内的一价离子及二价离子均可再生。操作电流应略大于极限电流，以保护产水质量。     

“双极膜-电去离子”耦合过程浓缩低浓度含镍离子溶液

电去离子(EDI)技术依靠离子交换膜和树脂表面自发的水解离特性实现深度脱盐功能,但处理含低浓度重金属离子溶液过程中,水解离产物OH-离子易与重金属离子生成金属氢氧化物沉淀,导致不可逆的破坏性影响.今将双极膜引入EDI膜堆,利用其内部的水解离产物实现预酸化和抑制树脂表面水解离功能,防止结垢并实现树脂再生.以含24 mg·...     

树脂填充床电渗析制高纯水的脱盐机理

树脂填充床电渗析是近年来发展起来的一种深度脱盐的新方法。这种方法由于在隔室中充填粒状离子交换树脂,不仅能降低脱盐室的电阻,而且能提高电流效率和极限电流密度。此外,树脂本身还可以交换水中残留的电解质离子,电渗析过程中由极化所产生的OH~-和H~ 也可用来使充填树脂得以再生。因此,它在纯水制备等多领域中得到了广泛的应用。在高纯电渗析过程中存在着电渗析、离子交换以及膜和树脂的极化、树脂的电再生三种作用。本文着重讨论这三种作用的相互关系及其深度脱盐的机理。     

Numerical simulation of the electrodeionization (EDI) process for producing ultrapure water

A steady-state model was established to simulate EDI process for producing ultrapure water (MixEDI), the dilute compartment of which is filled with mixed cation and anion-exchange resins. By calculating the mathematical model which includes water dissociation mechanism, ionic status of ion-exchange resin, concentration polarization status and the concentration distribution of water dissociation products are obtained. The influence of water dissociation on the current efficiency, removal rate and pH value of EDI effluent is investigated. The existence of water dissociation catalyst at anion-exchange membrane (AM) makes the water dissociation current of the AM much larger than that of CM. The result is that the amount of electro-regenerated cation-exchange resins is much larger than that of anion resins. This is the reason why the removal rate of salt cation much larger than that of salt anion in EDI for producing ultrapure water. Thus, at the target percentage removal, water dissociation at AM surface is excessive and the one at CM surface is insufficient. We assume that there is also some water dissociation catalyst at CM surface. It is found that the improved water dissociation at CM could increase the percentage removal of salt anions and the current efficiency.     

电去离子（EDI）高纯水新技术及其研究进展

介绍了EDI过程的脱盐机理,分析并提出了过程的主要强化途径。阐述了EDI的V-I、pH-I特征及“树脂电再生”等特征及其与电渗析（ED）过程的区别。介绍了国内外EDI的研究进展与应用概况。     

Numerical simulation of the electrodeionization (EDI) process accounting for water dissociation

The electrodeionization process (EDI) is usually operated at overlimiting current density, and is thus characterized by water dissociation and concentration polarization. We attempt to study the useful and harmful effects of water dissociation on the EDI process. A numerical steady state model was established to simulate the process of EDI, accounting for the effects of water dissociation. The differences in concentration polarization of membranes were investigated to study the effects of water dissociation on cation and anion membranes. Protons produced by water dissociation caused the resin to transform into the H-form. The H-form resin, which has high conductivity and high transport number, depletes protons in the interstitial solution. This explains the experimentally detected phenomenon that at high current densities, the pH value of the effluency of the dilute compartment (DC) stops decreasing when current increases. We suggest that the useful role of water dissociation in EDI is due to the H-form resin bringing more salt cations of the interstitial solution into the resin phase, thus producing a high conductivity channel for the electro-migration of the salt cations. This mechanism avoids the decrease in salt ion conductivity brought about by concentration polarization. The disadvantageous effect of concentration polarization on the transportation of salt ions in interstitial solution is thus lessened. An intermediate point between the useful and harmful effects of water dissociation was determined by the dependence of current efficiency and removal rate for both cations and anions as a function of current density.     

EDI连续脱盐机理的研究

介绍了EDI技术的基本特点,通过描述原水中含盐量和流速对膜堆的电流的影响,对EDI连续脱盐的机理加以解释。实验表明,原水含盐量较低时,在膜和树脂表面易于发生水解离,使淡水室中的树脂得到更好的再生;流速的大小变化对膜堆电流的影响不大,因此在低流速能够得到更好的水质。同时对淡水室树脂层态进行了分析,详细描述EDI脱盐工艺中的离子迁移行为。     

倒极电去离子过程浓缩分离含镍离子溶液

通过在电去离子(EDI)的淡化室和浓缩室中同时填充离子交换树脂而构成频繁倒极电去离子(EDIR)过程,用以解决处理含重金属离子溶液时EDI内部易产生金属氢氧化物结垢的关键难题。以NiSO4溶液为处理对象,采用浓缩水部分循环和浓、淡水流分步切换的运行工艺,利用EDIR单一过程,同步获得了淡化出水的高截留率和浓缩产品水的高浓缩倍数。实验条件下,倒极周期为4h可获最佳分离效果。对于含Ni2+50mg.L-1、pH为3.0的NiSO4溶液,EDIR的淡水出水和浓水出水的Ni2+浓度可分别达到1.5mg.L-1和3961mg.L-1,淡水中Ni2+的脱除率为97%,浓水的浓缩倍数则为79.2,接近理论值。实验范围内,EDIR过程运行稳定,未产生Ni(OH)结垢。     

膜集成技术在药用纯化水制备中的应用

兰州市某高校医学院以兰州市自来水为水源,采用预处理+二级反渗透(RO)+连续电除盐技术(EDI)+后处理的膜集成技术制取药用超纯水。运行结果表明,采用二级RO+EDI的膜集成技术制取药用超纯水是可行的,产品水达到分析实验室用水国家标准(GB/T 6682—2000)和中国药典(2010版)纯化水标准。     

EDI新技术及其在医药用水制备中的应用

电去离子(EDI)作为一种结合电渗析和离子交换两者优点的新型膜分离技术,现已逐步应用于医药、电子、电力、生物技术等领域。文章介绍了EDI技术工作原理,着重分析了其在国内外医药用水制备中的应用状况。EDI与RO等相结合的膜分离技术将是21世纪最有前景的医药用水生产技术之一。     

电去离子集成过程分级浓缩与纯化电镀镍漂洗废水

Successive concentration and purification of simulated nickel-electroplating rinsing wastewater was carried out by integrating membrane process with electrodeionization. The concentrate compartments were filled with ion exchange resins to enhance the separation. The concentrate stream of the primary EDI procedure was operated in closed circuit circulation. The influence of the volumetric ratio of resins in concentrate compartments on the separation was examined. It was found that the best performance could be achieved when anion to cation resin ratio of 6∶4 was adopted. With feed Ni²⁺ concentration of 50 mg·L^-1 and pH of 4.25,the Ni²⁺ concentration of effluent dilute stream could reach 2.78 mg·L^-1 while that of the effluent concentrate stream was as high as 11171 mg·L^-1,which gave a concentration ratio of higher than 220. The effluent dilute stream of the primary EDI was then sent to the second EDI stack for deep desalting. Dilute product with resistivity of 1.6—2.0 MΩ·cm was then obtained,which could be recovered as pure water for electroplating. The membrane process integrated with EDI could find its potent role for zero emission and resource reuse of heavy metal wastewater.     

The initial oxidation of beryllium by water vapor

The initial stage of adsorption and beryllium oxidation by water (clearly a nonadiabatic process) was studied for a wide temperature range, using AES, XPS, DRS, and CPD measurements. The mechanism of room temperature (RT) oxidation by water vapor was found to be by nucleation and growth of 3 monolayer oxide islands, laterally spreading until coalescence takes place. When a full oxide layer is achieved, a further slow oxidation takes place, virtually stopping at ∼6 monolayer depth. Exposure of the surface to water vapor at 150 K yielded dissociation to H and OH, chemisorbed on the surface, as detected by an XPS chemical shift. The lack of such a shift at RT indicates a full dissociation of the water molecule on the surface. A giant effect of Be electron-stimulated oxidation (ESO) by water vapor, as opposed to Be mild ESO by O₂, was observed, reaching the maximal possible oxidation rate for the ratio of ≥150 impinging electrons per water molecule. It is suggested that the mechanism is a Mott—Cabrera-like one, enabled by a combination of an electric field applied by negative OH and/or oxygen ions formed at the surface, probably by secondary electron attachment, and a very fast diffusion of Be²⁺ ions enabled by the presence of hydrogen in the oxide bulk. The water vapor ESO exhibits an inverse dependence on the substrate temperature, presumably due to the decrease with temperature of hydroxyl surface concentration, leading to the weakening of the electric field formed across the oxide.