扩散渗析法及其在工业废液处理中的应用

扩散渗析是利用半透膜或选择透过性离子交换膜使溶液中的溶质由高浓度一侧通过膜向低浓度一侧迁移的过程。扩散渗析工艺可以用于有机和无机电解质的分离和纯化,例如海水淡化、苦咸水脱盐等。在环境工程方面,目前主要用于酸、碱废液的处理和回收。本文介绍了扩散渗析法的原理、装置及其在工业废液处理中的应用和主要影响因素,并初步探索了扩散渗析法和其他膜技术的联合使用工艺。     

水中痕量镉的准液膜富集

准液膜法是在液膜法基础上提出的新分离方法，它保持了液膜法分离富集的高效能，但省去了液膜法的制乳与破乳过程，使操作更为简便易行。本文用此法富集了水及废水中痕量镉，富集倍数可达２３０倍，镉的回收率在９７％以上。     

太阳能淡化苦咸水

我国西北五省地处北纬45°以南,平均海拔1千米以上,大部分地区属于干旱区,雨量稀少,气候干燥,蒸发量大。有些地区虽然地下水源丰富,但由于水中含盐量大,既不能饮用又不能灌溉。近年来,有关单位开展了苦咸水淡化的多种科学实验,并在多级闪蒸、电渗析、反渗透等方面取得了很大进展,但这些方法成本高,技术复杂,向广大农村推广尚需改进和提高。在太阳能利用的群众性科学实验活动中,我们考虑到西北地区日照时间长、辐照强度大的特点,利用太阳能淡化苦咸水很有前途。1974年下半年,我们开展了太阳能淡化苦咸水的试验工作,1975年上半年到甘肃省会宁县实行贫下中农、干部、科技人员三结合,因陋就简,就地取材,建造了2平方米左右的小型太阳能蒸馏器,经过试验,管理方便,效果较好,受到广大贫下中农的欢迎。     

八甲基四氧咵特烷液膜载体的选择传质及负离子效应

自1968年黎念之研究液膜分离技术以来,该技术在湿法冶金、废水处理、苦咸水淡化、气体和化合物的分离、氨基酸及光学对映体的拆分等方面已展示了良好的前景。大块液膜分离技术用于筛选载体,考察各种因素对液膜传质速度的影响。其特点是简便、迅速,并可为乳状液膜及固载液膜的设计提供依据。液膜是将同它不相溶的另外两液相分隔开来的一种液相。在液膜体系中,阳离子与载体的配合物携带着它的反离子从源相经过膜相迁移到接收相,其迁移     

气体膜分离技术及其开发与进展

一、前言 本世纪60年代以来,膜分离技术取得了飞速发展。作为其分支之一的膜法气体分离也崭露头角,特别是自1979年美国Monsanto公司开发成功“Prism”中空纤维N_2/H_2分离器以后,已在全世界引起很大反响。各种新型膜材料和工艺过程不断涌现,经济效益与社会效益与日俱增,应用领域亦在日益拓宽。表1列举了迄今已实用化的膜法可分离的各种混合气体概况。     

苦咸水反渗透淡化中膜面结垢预测及防垢进展

苦咸水反渗透（BWRO）中的防垢过程,首先取决于给水水质,而根据水质条件和垢在膜面的形成机理采取相应的防垢措施是非常重要的。 显然,有效地管控膜面无机结垢及抑制膜面污染需要开展无机结垢趋势的预测、防垢措施和非破坏性无机垢监控等方面的技术研究。 一系列传统和新兴的分析技术,包括摩尔比率法、直接目测法和光谱法等已应用于BWRO过程中膜面防垢研究。 本文详细综述了该过程中无机结垢趋势的预测、防垢方法和非破坏性无机垢监控技术等方面的研究进展。 此外,针对目前的研究方向提出了建议。     

高取代度氰乙基纤维素与三醋酸纤维素共混反渗透膜的研制

本文以高取代度氰乙基纤维素(HCEC)和三醋酸纤维素(CTA)为共混体系,二恶烷和丙酮为溶剂,通过对 HCEC 与 CTA 的共混比、醇类添加剂以及影响膜性能的其他主要因素的研究,试制出具有优良耐微生物分解性能和适用于苦咸水或海水淡化的共混反渗透膜。在操作压力为3MPa,进料液 NaCl 浓度为0.35%的测试条件下,脱盐率分别为90%和99%的膜,其水通量为4.9ml/cm~2hr 和2.0ml/cm~2hr。     

渗透汽化汽油脱硫膜材料

渗透汽化膜法汽油脱硫技术是一种新型汽油脱硫技术,具有投资和操作费用低、辛烷值损失小等显著优点,受到人们的广泛关注。本文简要介绍了渗透汽化膜法脱硫的研究背景,基于溶解-扩散模型,以溶解度参数原则为理论指导,分析了聚合物脱硫膜材料的选择,结合近二十年来文献报道的渗透汽化脱硫膜研究进展,详细介绍了用于膜法脱硫的聚合物膜材料(聚二甲基硅氧烷、聚醚嵌段酰胺、聚乙二醇、醋酸纤维素、聚酰亚胺、聚磷腈等)及有机/无机复合膜材料的结构特点、改性方法及膜材料结构与性能间的关系,并将不同膜材料的脱硫性能进行了对比研究,在此基础上总结了目前渗透汽化脱硫膜存在的问题,并对其未来的研究方向和发展前景进行了展望。     

无支持膜法TiO2纳米管透射电镜观察

用透射电镜观察纳米量级的样品,通常要承载在具有支持膜的铜风上观察,铜网上制膜虽然有多种方法,但者需要有一定的过程,经过实践,我们采取无支持膜法用铜网直接捞取TiO2纳米管样品,在诱射电镜下观察获得了比较满意的结果。     

NEWS

膜分离技术在污水处理、中水回用、水质净化、海水淡化、血液透析和生物制药等领域得到了广泛应用。然而,膜在运行过程中出现的膜污染问题严重限制了该技术的发展。膜污染不仅会引起膜通量和分离性能下降,影响膜的长期稳定运行,而且污染后膜的清洗和更换也大大提高了运行成本。为了深入     

Integrated Valorization of Desalination Brine through NaOH Recovery: Opportunities and Challenges

The rising use of seawater desalination for fresh water production is driving a parallel rise in the discharge of high‐salinity brine into the ocean. Better utilization of this brine would have a positive impact on the energy use, cost, and environmental footprint of desalination. Furthermore, intermittent renewable energy can easily power the brine utilization and, for reverse osmosis technology, the entire desalination plant. One pathway toward these goals is to convert the otherwise discharged brine into useful chemicals; waste could be transformed into sodium hydroxide or caustic soda (NaOH) and hydrochloric acid (HCl). In this Minireview, we discuss opportunities and challenges for integrated valorization of desalination brine through NaOH and HCl recovery.     

Electrodialysis with Bipolar Membranes for Valorization of Brines

Several industrial processes, such as desalination or neutralization, generate brines defined as concentrated solutions of salts in water, usually NaCl, typically discharged in the vicinities of the desalination plant or factory. To reduce the environmental impact and promote the valorization of the wasted resources, alternatives must be sought. Among sustainable alternatives for the recovery of brines, the possibility of using Electrodialysis with Bipolar Membranes (EDBM) is of interest, because it allows recovering brines as useful acids and bases. This review focuses on the discussion of the technical aspects of the EDBM as a means to treat streams rich in NaCl from reverse osmosis desalination and industrial processes in order to complete the direct delivery of chemicals for self-supply. The main environmental issues associated with desalination brine disposal are presented. The state-of-the-art of valorization of brines by EDBM to acids and bases is completed. This work concludes with an in-depth discussion of the technical, techno-economic and economic barriers that prevent the widespread use of EDBM technology.     

阴离子交换膜的制备和改性研究进展

离子膜交换有广泛的应用,本文介绍了有机阴离子交换膜的修饰和改性以及新兴的有机-无机杂化阴离子交换膜的制备方法和发展现状,特别是介绍了近年来开发的一些不需要使用氯甲醚的阴离子膜制备新路线。     

Molecular and Morphological Designs of High Performance Polymeric Membranes

Currently, membrane separation techniques, such as reverse osmosis and ultrafiltration, play an important role in industrial separation technology. To develop high performance polymeric membranes, it is essential to design the molecular and morphological structures of the membranes for their specific applications. In the reverse osmosis field, we have developed several kinds of composite membranes for specific uses. Applications include ultrapure water production, seawater desalination, softening and desalination of brackish water, and recovery of valuable substances. In the course of development, thin-film composite membrane materials and membrane morphology have been analyzed intensively and are becoming clearer. These results enable us to control membrane performance by an optimum combination of membrane materials and membrane morphology. The morphological structure and chemical structure of the composite membranes were designed to optimize the performance of both the ultrathin layer and the supporting substrate layer for each membrane's application. As ultrafiltration is expanding to various fields, requirements for membrane performance have become more severe, especially for 1) sharpness of molecular weight cutoff, 2) solvent and high temperature resistance, and 3) fouling resistance (low nonspecific protein adsorption). To satisfy these requirements, we have developed a new ultrafiltration membrane. Owing to the high resistivity and hydrophilicity of its chemical structure, the membrane shows excellent solvent and high temperature resistance as well as fouling resistance. In addition, sharp molecular cutoff was realized by controlling membrane morphology.     

A study of selected phytoestrogens retention by reverse osmosis and nanofiltration membranes - the role of fouling and scaling

Fouling and scaling are common phenomena that accompany membrane filtration and are caused by the presence of organic and inorganic matter in water, which may affect the removal of low-molecular mass organic micropollutants. Comparative filtration of deionized water containing selected phytoestrogens (biochanin A, daidzein, genistein, and coumestrol) was carried out using one new membrane and one contaminated with organic or inorganic matter. Two commercial Osmonics DS membranes were selected for the research, reverse osmosis DS3SE and nanofiltration DS5DK. Filtration was carried out in the dead-end mode. Higher removal of phytoestrogens was caused by reverse osmosis and retention depended on the molar mass of the compound. The decrease in membrane efficiency associated with fouling or scaling brings about an increase in the retention coefficient of phytoestrogens during both reverse osmosis and nanofiltration. The highest increase in phytoestrogen retention was found for the nanofiltraton membrane which was more susceptible to fouling than the osmotic one. This confirms the effect of membrane porosity on the phenomenon studied. The increase in micropollutants removal observed after fouling or scaling was caused by the modification of the membrane surface, hindered diffusion of the compound, and intensified or limited adsorption of micropollutants on the membrane surface.     

Separate and Concentrate Lactic Acid Using Combination of Nanofiltration and Reverse Osmosis Membranes

The processes of lactic acid production include two key stages, which are (a) fermentation and (b) product recovery. In this study, free cell of Bifidobacterium longum was used to produce lactic acid from cheese whey. The produced lactic acid was then separated and purified from the fermentation broth using combination of nanofiltration and reverse osmosis membranes. Nanofiltration membrane with a molecular weight cutoff of 100–400 Da was used to separate lactic acid from lactose and cells in the cheese whey fermentation broth in the first step. The obtained permeate from the above nanofiltration is mainly composed of lactic acid and water, which was then concentrated with a reverse osmosis membrane in the second step. Among the tested nanofiltration membranes, HL membrane from GE Osmonics has the highest lactose retention (97 ± 1%). In the reverse osmosis process, the ADF membrane could retain 100% of lactic acid to obtain permeate with water only. The effect of membrane and pressure on permeate flux and retention of lactose/lactic acid was also reported in this paper.     

Enhanced transport properties and thermal stability of agro-based RO-membrane for desalination of brackish water

This present work focused on preparation of economic and high performance reverse osmosis membranes, characterized by high transport properties (salt rejection and flux) towards desalination of brackish water. In this respect cellulose acetate from sugar-cane bagasse (BCA) and polymethyl methacrylate (PMMA) wastes were used as the substrates of membrane. The function of PMMA for enhancing the performance of bagasse-based cellulose acetate RO-membranes was investigated at operating pressure 35.85 bar and feed temperature 25 °C. The effects of casting solution, percentage of polymer and treatment of polymer by alkali (HPMMA) on the performance of RO-membrane were discussed. The preferable composition (wt.%) of the 90% BCA and 10% HPMMA was achieved salt rejection 92.18% and flux 325.9 l h⁻¹ m⁻². High water purity was obtained by pre-passing the salted water through membrane made from dissolved bagasse (methylol cellulose) together with PMMA, instead of ion exchanger, followed by passing the accepted water through BCA–HPMMA membrane, whereas the salt rejection increased to 98%. Also, by this approach we obtained high thermal stability membrane compared to CA-RO-membrane. This data gives highlight on possibility of application such type of membrane with high temperature operation conditions.     

Photocatalytic Treatment of Desalination Concentrate Using Optical Fibers Coated With Nanostructured Thin Films: Impact of Water Chemistry and Seasonal Climate Variations

Treatment of desalination concentrate can reduce concentrate volume for disposal, increase water recovery and convert waste to resource. However, concentrate treatment is costly and energy intensive due to high concentrations of salt and recalcitrant organic matter in concentrate. Photocatalytic oxidation provides a novel energy neutral technology for concentrate treatment by degrading organic contaminants. Polymer‐assisted hydrothermal deposition method was used to synthesize innovative pure and Fe‐doped TiO₂ mixed‐phase nanocomposite thin films on side‐glowing optical fibers (SOFs). The properties of the photocatalysts‐coated SOF were characterized by surface morphology, nanostructure, crystallite size and phase and zeta potential. Photodegradation efficiency and durability of the photocatalysts treating different types of desalination concentrate was studied under natural sunlight. Synthetic solutions and reverse osmosis (RO) concentrates from brackish water and municipal wastewater desalination facilities were tested to elucidate the impact of water chemistry, operating conditions and seasonal climate variations (solar irradiation intensity and temperature) on photocatalytic efficiency. High ionic strength and divalent electrolyte ions in RO concentrate accelerated photocatalytic process, whereas the presence of carbonate species and organic matter hindered photodegradation. Outdoor testing of immobilized continuous‐flow photoreactors suggested that the catalyst‐coated SOFs can utilize a wide spectrum of natural sunlight and achieved durable photocatalytic performance.     

Effect of environmental temperature and applied potential on water desalination performance using electrodialysis

Desalination of brackish water is a challenging task for higher recovery of water. In most of the cases, water recovery is low with high wastage. Electrodialysis (ED) provides a solution of water desalination with high recovery. Ion-exchange membranes are the main component for electrodialysis system. Here cation-exchange membrane and anion-exchange membrane were synthesized by free-radical polymerization for water desalination by ED. ATR-FTIR confirms the successful functionalization of the membranes and scanning electron microscopy technique reveals the dense morphology of the membranes. Here we used polyethylene as a binder and blow film extrusion for film formation, which is not only economically viable as well as large amount of membranes can be produced without using hazardous solvent. The desalination study reveals the improvement in desalination performance with slight increment in temperature which may be due to higher ionic mobility. The mechanical and thermal stability of the membranes was characterized to ensure the viability of membranes for desalination at higher temperatures. Effect of applied potential was also studied in the removal of pathogens during desalination and confirmed that 2 V/cell pair applied potential removes almost 97% pathogens during desalination in continuous mode.