电渗析膜污染与清洗技术研究进展

电渗析技术作为一种膜分离技术,随着对传统电渗析过程的改进,使电渗析技术成为新的热门研究领域。而研究离子交换膜的污染规律,建立起有效的缓解和清除膜污染措施,是解决电渗析技术更广泛应用的一个关键问题。本文分析了电渗析膜污染的成因和污染的防治,并对电渗析膜的清洗方法做了综述。     

工业废水电渗析过程中膜污染研究进展

综述了工业废水电渗析体系膜污染类型、性质、影响因素等的研究进展. 无机污染主要是Ca2+, Mg2+或其他高价离子在离子膜表面或内部形成的结垢现象,原理是极化或溶液过饱和形成沉淀. 有机污染是由蛋白、腐植酸、表面活性剂及大分子有机物在离子膜表面沉积或渗透到膜内部而形成,原因主要是带负电荷的有机物与阴膜荷正电基团的静电作用及带苯环有机物与基膜的亲和作用,其次是有机物分子大小与膜的网络结构的作用. 膜污染形成及其性质与施加电流、共存组分、温度、pH值和运行时间等密切相关,可造成离子膜导电性、离子交换容量、水含量和极限电流密度等减小,且有机污染对电渗析性能的影响比无机污染更严重. 由有机物凝胶层形成的膜污染可用电渗析膜污染指数定量描述.     

电渗析离子交换膜污染控制措施研究

为了解决电渗析技术处理垃圾渗滤液MBR产水过程中的膜污染问题,采用电絮凝和臭氧氧化2种预处理方式对MBR产水进行预处理,考察2种预处理方式对离子交换膜污染的控制效果。研究结果表明,经过电絮凝预处理后的废水COD和吸光度分别降低26.1%、 14.5%,经过臭氧氧化预处理后的废水COD和吸光度分别降低28.0%、 87.8%,电絮凝和臭氧氧化预处理使得膜电阻比没有经过预处理时分别下降了7.74%和52.87%,臭氧氧化预处理对电渗析过程中膜污染现象的预防效果优于电絮凝技术;采用pH值为11的NaOH溶液可以有效地恢复离子交换膜的性能,清洗后的膜电阻和脱盐效率均可以恢复到初始状态。     

双极膜电渗析在环境污染控制中的应用进展

环境问题是当今世界可持续发展必须直面的世界性课题,在该背景下,环境污染防治研究具有重要意义。膜处理技术作为一种高效绿色的新型处理技术,在污染控制方面有着广泛的应用空间。对双极膜电渗析及其耦合工艺在环境污染控制中的应用进展进行了总结,并就该技术的应用前景与研究方向进行了分析和展望,以期为双极膜电渗析的工业化应用提供参考与借鉴。     

双极膜电渗析技术的研究进展

在电场作用下,双极膜内的水能快速解离产生H~+和OH~-,这一电化学特性使双极膜电渗析(BMED)逐渐发展为一种新型膜分离技术。首先介绍了BMED的基本工作原理,综述了其发展历程,接着介绍了近年来其在酸碱生产、污染控制、与其他化工技术耦合作用等方面的研究进展,最后提出目前应用中存在的问题,并对BMED的未来发展进行了展望。     

双极膜电渗析技术的研究进展

双极膜电渗析技术(BMED)是利用直流电场作用下双极膜界面层内发生水解离生成H+和OH-这一电化学特性,通过将双极膜与阴、阳离子交换膜适当组合,可实现不同的特种分离功能。与传统工艺相比,BMED具有高效节能、环境友好、操作便捷等突出技术优势。本文介绍了3种不同的BMED工作模型以及BMED在有机酸生产、水除盐、蛋白分离、超纯水制备等领域的最新研究进展,对BMED技术的进一步研究与发展进行了展望。     

双极膜及其研究进展

介绍了双极膜水解离电渗析技术的原理,双极膜的制造、应用以及国内外对双极膜的研究及发展动向。     

膜污染分析及防治

本文综述了膜污染的分析技术,膜污染的影响因素,防止膜污染的措施,膜污染的清洗方法及常用的清洗剂,还介绍了膜污染的定义、膜污染的形式及其新进展。     

钙盐和氨基酸对味精等电母液模拟料双极膜电渗析过程膜污染的影响

采用恒压分批操作方式考察了味精等电母液模拟料液中钙盐和氨基酸对双极膜电渗析过程膜污染的影响.结果表明,在处理含氨基酸和Ca2+的盐溶液时,碱室溶液中检测到各氨基酸含量为Glu＞Ala＞Gly＞Thr＞Lys,它们与料液中NH4+同步迁移至碱室,迁移量与料液中氨基酸浓度成正比;料液中Ca2+是引起碱室侧阳膜面出现固形污染...     

MBR膜污染机理及其控制

本文论述了膜生物反应器中膜的污染机理及其控制。     

Recent advances in reverse osmosis and electrodialysis membrane desalting technology

The potential impact of recent developments in both reverse osmosis and electrodialysis membrane desalting technology are summarized.Particular emphasis is given to the status of advanced technology reverse osmosis membranes with chlorine resistance having single pass seawater desalination capability. Membranes capable of using low operating pressures for brackish water desalting are also reviewed.Results obtained with large prototype reverse osmosis modules and their potential effect on lowering plant capital costs are presented.Possible elimination of acid and use of ultrafiltration as the predominant pretreatment step in seawater desalination plants are also described.Recent developments in the high temperature electrodialysis program for seawater desalting and in the use of newly developed anion membranes for brackish water desalination are reviewed.Finally, the effect of recent budget cut-backs imposed on the office of Water Research and Technology (OWRT) and potential impacts on future membrane desalination R&D activity are discussed.     

Recent advances in reverse osmosis membranes

A review is presented of the developments of the past several years in the area of reverse osmosis membranes. These developments have occurred along two lines: new membrane materials and new membrane fabrication methods. Among the new materials can be cited aromatic polyamides, polybenzimidazole, polyphenylene oxide, hydrated metal oxides, crosslinked and blended cellulose acetates, crosslinked polyvinylpyrrolidone, crosslinked polyethylenimine, and derivatives of several of these materials. The water and salt permeabilities of many of these materials and of the cellulose acetates are compared.Important developments in the area of fabrication methods include the extension of asymmetric membrane techniques to new materials, supported ultra-thin films, hollow fibers and asymmetric hollow fibers, and dynamically formed membranes. A comparison of these materials and fabrication methods requires some kind of figure of merit and one such parameter is discussed.     

Membrane fouling in electrodialysis: a model and experiments

Membrane fouling is a common cause for poor performance in electrodialysis systems, usually because it reduces the limiting current. Fouling may be caused by deposits of either neutral matter or colloidal matter with ion exchange properties. In the present paper a model for membrane fouling is developed and expressions are derived for the reduction in limiting current caused by both neutral fouling films and films having ion exchange properties. The effect of fouling is shown to depend not only on the properties of the fouling film, but also on the hydrodynamic conditions in the channels and in the case of ion exchange fouling films on the salt concentration in the dialysate channel. Ion exchange fouling films are shown to be much more effective in reducing the limiting current than neutral films. Some experimental data are presented which confirm the trend of the theory for fouling with ion exchange films.     

Polarization at ion-exchange membranes in electrodialysis

In an attempt to investigate polarization phenomena (including substantial participation of H⁺ and OH^- in conduction) which seriously limit the production rates of electrodialysis units, current-voltage curves were measured in different sections along the tortuous flow path of an electrodialysis apparatus containing a single anion-exchange membrane of size 20″ × 18″. The electrical potential drops across this membrane and the adjacent solution layers were measured with silver electrodes terminating in exposed chloridized tips, placed in the two flow compartments adjacent to the anion-exchange membrane. While the measured current- voltage curves exhibit true limiting-current plateaus only in the last sections, all sections yield plateau currents after correction for the measured variation of coulombic efficiency. Moreover, these corrected curves are in fair agreement with those computed from the solution of the Nernst-Planck equations of ion migration, as developed in this paper to take due account of the variation of salt concentration along the flow path.     

反渗透膜污染成因与防治

反渗透膜的污染受膜自身性质、水质和操作条件的影响.综述了膜材料、膜结构和膜组件、操作温度、压力、pH值、剪切速率和水质对反渗透膜污染的研究现状,同时指出研制低/抗污染膜和膜组件,优化操作条件.增设水质预处理和有效的膜清洗是反渗透膜技术的发展方向.     

反渗透膜污染成因与防治

反渗透膜的污染受膜自身性质、水质和操作条件的影响。综述了膜材料、膜结构和膜组件、操作温度、压力、pH值、剪切速率和水质对反渗透膜污染的研究现状,同时指出研制低／抗污染膜和膜组件,优化操作条件．增设水质预处理和有效的膜清洗是皈渗透膜技术的发展方向。     

Desalination of fish meat extract by electrodialysis and characterization of membrane fouling

Fish meat extract (FME) desalination via electrodialysis (ED) was performed and the changes of important parameters such as membrane stack potential, brix, pH, and electrical conductivity were examined for a quantitative evaluation. The change of electrical conductivity in diluted or concentrated solutions showed that the mineral ions contained in the FME could be effectively removed. The characterization of membrane fouling indicated that the organic/ inorganic components deposited, respectively, on the surfaces of anion/cation exchange membrane and resulted in the increase of membrane electrical resistance. Ion chromatograph (IC) analysis showed that the main mineral ions, such as Na⁺ and Cl⁺ ions contained in the FME, were removed about 82.3% at an average current efficiency of around 77.9% via ED. By considering the removal rate of mineral ions and current efficiency, the feasibility of FME desalination via ED was proved.     

Boron removal by electrodialysis with anion-exchange membranes

The removal of boron from an aqueous solution was studied in a two-chamber cell separated with a commercial anion- exchange membrane as a function of current density, pH, type of the membrane, concentration and different type of salt solutions. At the end of these studies, the maximum value of boron removal was obtained under the conditions where the maximum current was applied; 0.1 M H₃BO₃ (pH = 9) and 0.001 M NaCl solutions were used as a catholyte and an anolyte solution, respectively. The AHA membrane was used for separating the two cells used in the electrodialysis experiments. All experiments were carried out at room temperature, and the concentration of boron at the anode cell was determined by ICP–AES. It was concluded that electrodialysis is an appropriate method for boron removal from aqueous solutions under suitable conditions.