共查询到19条相似文献,搜索用时 78 毫秒
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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. 相似文献
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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。 相似文献
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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. 相似文献
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H.K. Lonsdale 《Desalination》1973,13(3):317-332
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. 相似文献
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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. 相似文献
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《Gas Separation & Purification》1989,3(4):162-169
Cellulose acetate membranes have been used commercially for many gas separation applications in recent years. Advances have been made in understanding their behaviour in the presence of various vapours and under severe operating conditions, for example at very high carbon dioxide and hydrogen sulphide partial pressures. In addition, a new membrane module design has been developed for use in high recovery systems and at high gas flow rates. Extension of cellulose acetate gas separation membrane technology into the pervaporation field has resulted in a new application related to the production of methyl t-butyl ether (MtBE). In this case the membrane is used to remove methanol from MtBE and hydrocarbons to increase the reaction yield. 相似文献
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节能高效的CO2分离技术的开发具有重要的现实及长远意义,膜法CO2分离在该领域备受关注,具有优异传质特性的新型分离膜材料对膜分离过程有决定性的影响。近年来,石墨烯及其衍生材料因独特的单原子层厚度、亚纳米级别的孔道结构以及优异的机械、化学和热稳定性,成为气体分离膜领域的研究热点,膜的加工难度、技术成本、大面积制备、工作稳定性等问题是限制其实际应用的关键因素。石墨烯基CO2分离膜主要有三种形式:纳米孔石墨烯膜、层状结构氧化石墨烯膜、基于石墨烯及其衍生材料的混合基质膜。本文综述了石墨烯基CO2分离膜领域的突破性研究进展,重点介绍了气体的跨膜传质机理和膜的构性关系,总结了膜性能的优化思路和原理,梳理了石墨烯基CO2分离膜发展面临的挑战,提出了潜在的研究方向。分析表明,进行系统的理论研究,采用先进的表征手段,以建立膜构性关系的理论模型,指导膜结构设计是未来研究的重点。此外,进一步降低膜加工成本,充分研究膜在实际工作环境中的稳定性也至关重要。 相似文献
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Membrane and membrane process have been considered as one of the most promising technologies for mitigating CO2 emissions from the use of fossil fuels. In this paper, recent advances in polymeric membranes for CO2 capture are reviewed in terms of material design and membrane formation. The selected polymeric materials are grouped based on their gas transport mechanisms, i.e., solution‐diffusion and facilitated transport. The discussion of solution‐diffusion membranes encompasses the recent efforts to shift the upper bound barrier, including the enhanced CO2 solubility in several rubbery polymers and novel methods to construct shape-persisting macromolecules with unprecedented sieving ability. The carrier-bearing facilitated transport membranes are categorized based on the specific CO2-carrier chemistry. Finally, opportunities and challenges in practical applications are also discussed, including post-combustion carbon capture (CO2/N2), hydrogen purification (CO2/H2), and natural gas sweetening (CO2/CH4). 相似文献
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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. 相似文献
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Adsorptive membranes with filtration and adsorption functions are one of the best strategies to remove harmful cations from wastewater and drinking water. In view of adsorptive capacity and regeneration cost, the most promising application field of adsorption membrane is the production of drinking water at present. An overview is given about the research progress of adsorptive membranes for removing heavy metal ions from drinking water. The removal mechanism of adsorptive membranes is explained by a schematic representation of electrical double layer. The types of adsorptive membranes are summarized. Future research outlook regarding adsorptive membranes is also discussed in order to promote research and application in drinking water for adsorptive membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48579. 相似文献