电去离子法(EDI)处理电镀含铬废水

电去离子法(EDI)是电渗析和离子交换的结合技术.在电渗析淡室中添加离子交换树脂作为阳极室介质,自制了EDI装置,并采用该装置对电镀铬漂洗废水进行处理,研究了进水pH、流量和电流密度对EDI分离效率的影响.结果发现,当进水pH=4.8,流量和电流密度分别为4 L/h和1.2 mA/cm2时,Cr(VI)的分离效率可达99.5％,但淡室出水中的Cr(Ⅵ)浓度略高于国家排放标准.作为一种能够高效分离电镀铬漂洗废水中六价铬的新技术,EDI仍有一些问题需要解决.     

电渗析法脱除三羟甲基乙烷中甲酸钠

三羟甲基乙烷中甲酸钠的含量是影响产品性能的重要指标。本文采用电渗析方法代替离子交换树脂法脱除三羟甲基乙烷中的甲酸钠,考察了操作电压、淡室初始浓度、淡室流速、浓室初始浓度等操作条件对脱盐效果的影响。结果表明：操作电压为8V,淡室浓度0.15mol/L,淡室流速0.529cm/s,浓室初始浓度0.01mol/L甲酸钠溶液的条件,脱盐率达到95%,电渗析可有效用于三羟甲基乙烷中甲酸钠的脱除。从环境保护和资源消耗方面考虑,电渗析法优于离子交换树脂法用于脱除三羟甲基乙烷中的甲酸钠。     

EDI膜堆填充材料及其填充方式的研究进展

介绍了EDI膜堆填充材料的研究现状,认为离子交换树脂仍是今后填充材料的主要研究对象,离子交换纤维和其它新型填充材料的研究亟待有新的突破。同时,以树脂为例,对离子交换材料的3种填充方式（混合填充、分层填充、分置式填充）进行了系统介绍。最后对EDI膜堆填充材料及其填充方式的研究与发展作了展望。     

电去离子运行过程中的结垢问题及其防止措施

在简要介绍电去离子(EDI)基本原理及其应用的基础上,提出了膜堆结垢是EDI应用过程中的主要问题,分析了膜堆结垢的原因及其预防措施,认为有效防止膜堆结垢的关键因素:控制EDI的进水硬度、CO2浓度等合理的预处理工艺;通过极水室和浓水室中填充离子交换树脂降低膜堆电阻的结构设计.     

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。     

电去离子新技术及其制备注射用水的可行性分析

采用国产化材料组建电去离子(EDI)膜堆,并对EDI膜堆结构进行改造,在其浓水室填充离子交换树脂。试验研究表明,二级EDI膜堆与一级EDI膜堆比较,适应性强、产水水质好且在较短的时间内就基本达到稳定。二级EDI膜堆运行电流控制在2～3 A条件下,产水电阻率可在40 min以后基本稳定在17 MΩ.cm以上。在此基础上提出了一种新型的非蒸馏法注射用水制备工艺即反渗透-二级电去离子-超滤(RO-2EDI-UF)工艺。研究表明,RO-2EDI-UF制备注射用水,在理论上是可行的;工程实例也证明,产水电导率、细菌内毒素等各项指标均达到中国药典对于注射用水的标准。此工艺可显著降低系统设备投资、降低能耗,减少污水排放和噪声污染,水利用率较高,所制的注射用水具适宜的温度。完全可以替代离子交换法和蒸馏法用于注射用水的制备。     

电渗析用于多元醇溶液脱盐的实验研究

考察了操作电压、浓淡室流速比、浓淡室溶液体积比3种操作条件变化对普通离子交换膜、化工分离专用离子交换膜、均相离子交换膜脱盐性能的影响。研究表明,采用电渗析法能够有效脱除多元醇溶液中有机酸盐,化工分离专用离子交换膜的综合性能优于普通离子交换膜和均相离子交换膜,当采用化工分离专用离子交换膜浓淡室流速比为3∶1时,多元醇损失率为1%,浓淡室溶液体积比为1∶4时,对化工分离专用离子交换膜性能基本没有影响。     

1种简易电去离子装置的建立及对含Cu~(2+)废水的处理

基于自制板柱结构电去离子装置,探讨了浓水室填充离子交换材料(树脂、离子交换织物)处理低Cu2+含量废水的效果。经过100h运行结果发现,在浓水室中填充离子交换材料能够促进离子迁移,提高电去离子能力和出水水质,同时可缓解阴离子交换膜浓室侧表面的沉淀现象;更长时间运行后也发现,阴离子交换膜和树脂的季铵盐基团转变为叔胺基团,催化水解反应,加剧了离子交换膜和树脂表面沉淀结垢,使电去离子效果恶化。     

双极膜电去离子过程制备四甲基氢氧化铵

采用酸室填充离子交换树脂的双极膜电去离子(BMEDI)装置,以四甲基氯化铵(TMAC)为原料制备四甲基氢氧化铵(TMAH).研究了树脂体积比、电流密度和原料浓度对TMAH制备过程的影响,并对2种不同的均相阴膜进行了对比考察.结果表明,在电流密度40 mA·cm-2,原料TMAC浓度0.1 mol·L-1的条件下,TMAH转化率可达91.2%.电流密度提高,TMAH转化率和过程能耗随之增大,在更高的原料浓度下可获得更高的电流效率,酸室填充100%阴树脂效果较好.此外,与JAM-10膜相比,UTX-UIF-A膜的面电阻较小,取得了更佳的试验效果.     

电去离子法处理偏二甲肼废水

用填充强酸性离子交换纤维的电去离子（EDI）装置,处理实验室模拟的火箭发射场偏二甲肼废水。考察了电流、出水pH值与电压的关系以及模拟水样经循环处理的效果。结果表明,与电渗析相比,采用EDI处理废水的效率较高,在一定电压下,膜堆内部水的极化主要发生在阴离子交换膜的表面。水样经循环处理后,淡水出水可以达到排放标准,浓缩液中偏二甲肼质量浓度达到3396.7mg/L以上。物料衡算可知,极水中的偏二甲肼易被氧化。     

电去离子技术处理低浓度重金属废水研究进展

阐述了电去离子(EDI)过程的去离子原理,综述了EDI技术处理低浓度重金属废水过程中,离子交换介质与离子交换膜的应用,以及床层结构、膜堆构造和工艺流程的最新进展,分析了现有几种传质模型的优缺点,提出了目前存在的问题和今后发展的方向。     

两种不同电去离子技术处理含铜金属离子废水的研究

研究了倒极电渗析技术(EDIR)和电去离子技术(EDI)过程中淡出水和浓水室的电导率、p H值、铜离子浓度和膜堆电流,以及运行后离子交换膜和树脂的表面形态。结果表明:EDIR运行15 h的淡出水的电导率为30μS/cm,16 h的铜离子去除率为97.2%。EDI过程中15 h淡出水的电导率550μS/cm,16 h的铜离子去除率为77.8%。EDIR使淡出水的电导率降低,铜离子去除率升高。EDIR淡出水的p H值长期维持碱性,EDI淡出水则由碱性变成酸性、再变成碱性。然而,EDIR和EDI过程中浓水室的电导率和p H值基本接近。EDIR降低了膜堆电流、消除了浓水室阴离子交换膜表面氢氧化铜沉淀,抑制了淡水室中混合树脂表面沉淀。本质上,EDIR通过周期性改变淡水室和浓水室的相对数量和离子迁移方向而消除了膜表面氢氧根离子富集,并缓和了树脂表面水解现象,从而改善了EDIR过程的稳定性。     

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.     

回收重金属废水用电去离子技术研究进展

电去离子(EDI)技术是由电渗析和离子交换相互有机结合的膜分离脱盐技术.其具有连续运行、不用酸碱、环境友好等显著优点.作者介绍了国内外采用电去离子技术回收含铜和含镍废水的研究进展,针对重金属废水的特点,设计了以阳树脂为主的阴、阳树脂分层填充的电去离子装置,采用该技术代替传统的离子交换技术,可实现重金属废水的回收和利用.达到闭路循环、零排放、无污染的目的.     

电去离子技术及其应用进展

电去离子技术作为将电渗析及离子交换技术有效结合的新一代的水处理技术，因其绿色、环保、经济的优势，成为了现代主要的纯水制备技术，广泛应用于工商业领域。在研究分析电去离子技术的基本原理及工作机理的基础上，对现有淡室的填充材料及填充方式进行了总结分析，得出混合填充为最佳方式，且未来可加强对离子交换纤维膜材料的开发，减少电去离子技术工艺处理时间。最后，对电去离子技术的发展历程及近10 a的技术应用情况进行综述，未来可推进电去离子技术广泛应用于无机离子提取等领域。对新型无膜电去离子技术的机理研究有利于该项技术后期大规模的产业化应用。     

用电去离子过程从稀溶液中回收镍离子并制备纯水

利用基于EDI工艺的单个过程实现了低浓度废水中镍的回收并同时制备纯水.研究表明:当原水镍含量为55ppm时,镍去除率可达99.9%以上,淡水产水中镍的浓度低于0.05mg·L-1,其电阻率稳定在2.02～2.59MΩ•cm,浓水中镍浓度则可高达1263mg·L-1.该研究充分证明了EDI可用于回收低浓度含镍废水中的镍离子且同时产生优质纯水,从而可实现如电镀等行业的清洁生产和闭路循环。     

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.     

Experimental Studies on Electrodeionization for the Removal of Copper Ions from Dilute Solutions

Abstract

The purpose of this study is to investigate the ability of electrodeionization to remove copper ions from dilute solutions without chemical regenerations. Experiments were carried out in a bench‐scale stack using a feed solution containing about 50 mg/L of copper. It was demonstrated that electrodeionization operated in either the “enhanced transfer” or the “electroregeneration” regime. In the “electroregeneration” regime, the process was able to produce a pure water product containing non‐detectable concentrations of copper, while CuO scale was found on the surface of anion exchange membranes. With optimal conditions, a steady and continuous process can be achieved.     

电去离子技术处理电镀含铜废水

采用一种改进的电去离子装置处理电镀含铜废水,考察了电极室溶液和操作电压对处理效果的影响.结果表明,特殊的膜堆构造使得装置的浓室始终保持酸性环境,抑制了铜离子在阴离子交换膜表面形成氢氧化铜沉淀,克服了传统电去离子过程中普遍存在的二价金属离子氢氧化物沉淀现象.电极室溶液中加入少量Na2SO4电解质和增大操作电压可显著提高废水处理效果.运行过程中铜离子浓缩倍数5～l4,铜离子去除率大于99.5％,出水中铜离子浓度低于0.25 mg·L-1,可达标排放或循环利用.     

Cr(VI) removal by continuous electrodeionization: Study of its basic technologies

The capabilities of continuous electrodeionization process (CEDI) and its basic technologies (electrodialysis (ED) and ion exchange (IX)) were analyzed in order to remove hexavalent chromium from synthetic solutions at pH 5. A cell with two chambers (dilute and concentrate) was used. Two cation exchange membranes (CM-1) and one anion exchange membrane (AFN) (40 cm² effective area) were employed in the experimental setup. IX technology was single evaluated using an IRA-67 anionic resin to know its independent performance from the other technologies, whereas ED was studied in the cell; I_lim determination was done by I vs. U plots and factors of 0.7 I_lim and 0.85 I_lim were applied to ED process. Finally, EDI process was studied at the same conditions that ED in order to know the resin bed role. During IX the removal reached was 50%; ED 98% after 6.25 h operation with an energy consumption of 1.21 kW h/m³; EDI (anionic bed) accomplishing 97.55% chromium removal (energy consumption of 0.91 kW h/m³). Finally EDI with mixed bed removed 99.8% in 1.3 h and of 0.167 kW h/m³ of energy consumption.