双极膜电渗析技术在工业高含盐废水中的应用

双极膜电渗析（BMED）作为新型膜分离技术,可将盐转变为相应的酸和碱,围绕BMED技术在工业高含盐废水领域的应用已逐渐成为热点,但在实际应用中还存在一些亟需解决的难点。本文主要介绍了近年来BMED技术在处理工业高含盐废水领域的研究现状,提出和探讨了限制BMED技术在该领域大规模工业化应用的3个关键性问题,即与酸碱浓度和纯度有关的技术问题、与过程成本有关的技术经济性问题以及与投资成本有关的经济性问题。针对这3个问题,指出BMED技术未来发展方向应致力于降低双极膜成本,减弱或消除离子交换膜同离子泄漏及水迁移过程。对于现阶段而言,将制备的酸碱回用于系统内部,是解决酸碱品质较低而未能商品化的主要途径,同时该过程可节省酸碱外购费用,弥补BMED技术投资成本过高问题。     

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。     

双极膜电渗析清洁制备NaOH和H2SO4的试验研究

采用双极膜、阴离子交换膜和阳离子交换膜交替排列构成的五隔室双极膜电渗析(BMED)构型,以Na2SO4为原料制备NaOH和H2SO4。研究了电流密度和原料液浓度对膜堆操作性能的影响,并对2种不同的均相阳膜进行了对比考察。结果表明,在电流密度50 mA/cm2,Na2SO4原料液浓度10%的条件下,试验范围内NaOH的收率可达79.63%,其收率和能耗随电流密度的增大而增加;电流密度恒定时,较高的原料液浓度利于保持更小的膜堆电阻,过程能耗相应降低。将BMED制得的稀NaOH和H2SO4溶液直接用于饱和阴、阳离子交换树脂的再生处理,并将其与经常规酸碱试剂化学再生的树脂均用于反渗透产水的深度除盐制备纯水,结果前者所获水质纯度显著优于后者,表明BMED所制备的酸碱纯度更高,树脂再生更为彻底。     

双极膜分离技术及应用进展

双极膜通过对水解离具有的催化效应,能够使水中的盐重新转变为酸和碱,在环境保护和资源回收等领域发挥着越来越大的作用。本文解析了双极膜的“三明治”结构特点、发展历程及发展趋势、制备工艺技术,阐述了双极膜催化水解离机理的3个模型：第二Wien效应模型、化学反应模型以及中和层模型。探究了双极膜电渗析及与其它化工过程耦合技术在不同领域的应用,其中包括酸碱生产领域、资源分离回收领域以及污染控制领域等。分析了双极膜的具体应用过程中存在的局限性并展望了双极膜在水解制氢、液流电池方面的应用前景。指出双极膜将朝着与传统化工过程、新型液流电池等系统集成化、规模化方向发展,成为多种化工应用领域的重要组件。     

双极膜电渗析法麦草畏生产废水的资源化利用研究

采用双极膜电渗析（bipolar membrane electrodialysis,BMED）将麦草畏生产废水中的NaCl转化为HCl和NaOH回用于农药生产,实现农药废水的资源化利用。首先进行了BMED法处理单组分NaCl溶液体系的110 min间歇运行实验来探索最优操作条件,结果表明,当NaCl初始浓度为160 g/L,电流密度为70 mA/cm²,初始酸碱室浓度为0.075 mol/L时,产物HCl、NaOH的浓度能分别达到1.98 mol/L和 2.06 mol/L,且此时的电流效率较高,达到42.74%。然后考虑实际废水的COD指标主要是甲醇造成的,所以用含不同浓度甲醇的NaCl溶液模拟实际农药废水,实验结束后在酸、碱隔室中检测到少量的甲醇,表明其在BMED运行过程中存在一定程度的渗透,但未对膜堆性能造成明显影响。最后用BMED处理经过预处理后含有机物的麦草畏生产废水,发现在操作时间内膜堆性能与处理高浓度单组分NaCl溶液情况类似,证实BMED法处理麦草畏生产废水并实现资源化利用的可行性。     

电驱动膜过程在氨基酸发酵液处理中的研究进展

在发酵法生产氨基酸的过程中,需要后续工艺对发酵液进行分离纯化以提取目标产物.电驱动膜过程正逐渐成为该领域研究与应用的热点.本文介绍了近年来国内外普通电渗析(ED)、双极膜电渗析(BMED)、离子取代电渗析(ISED)、电复分解反应器(BMT)等常见的电驱动膜过程在氨基酸发酵液处理中的研究进展,简述了常见的膜堆构型及其工作原理、特点与应用实例.分析表明电驱动膜过程可以实现混合氨基酸分离、无机盐脱除以及氨基酸的制备,膜堆结构、操作参数的优化以及新型分离膜的研究与应用可以提高过程性能.同时也指出目前该领域的研究尚处于实验室研究阶段,研究对象以模拟发酵液为主,规模化应用的报道还不多见.但是可以预见高效、环保的电驱动膜过程将会在氨基酸发酵液处理中发挥重要作用.     

双极膜电渗析的理论研究进展与应用

从理论和应用研究两方面较为全面地综述了双极膜电渗析技术在近些年的发展,阐述了双极膜中水解离、水迁移、离子迁移以及双极膜电渗析过程等理论研究。介绍了它在饮用水及纯水的制备、食品工业和化学工业及其他领域中的应用。双极膜电渗析技术在优化传统工艺过程和新的工业过程中发挥独到的作用,它的出现改变了传统工艺分离和制备过程,为解决环境化工,生物,海洋化工等领域中的技术难题注入新的生机和活力。同时为解决人类面临的环境,资源,能源的问题提供了有效手段。     

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。     

双极膜的发展和应用

本文简述了双极膜技术在当今电渗析技术中的地位、发展状态及双极膜水解离的原理。总结了双极膜的制备方法，例举了双极膜水离解技术在诸多方面的应用。     

具有不同取代基金属酞菁衍生物改性SA/CS双极膜

分别用八羧基铜酞菁、四磺酸基铜酞菁对海藻酸钠阳膜和四氨基铜酞菁对壳聚糖阴膜进行了改性,制备了金属酞菁衍生物改性海藻酸钠/壳聚糖双极膜,并用热分析、电子万能试验机、接触角测定仪和J-V关系等对改性海藻酸钠/壳聚糖双极膜进行了表征。实验结果表明,金属酞菁衍生物改性海藻酸钠/壳聚糖双极膜的热稳定性、力学性能和亲水性均获得提高。金属酞菁衍生物在双极膜中间界面层形成高荷电区,促进了中间界面层水的解离,从而降低了海藻酸钠/壳聚糖双极膜的膜电压。具有不同取代基的金属酞菁衍生物对中间界面层水解离的催化能力不同,这与不同取代基的金属酞菁衍生物改性膜的亲水性大小有关。     

Asymmetric bipolar membrane electrodialysis for acid and base production

Bipolar membrane electrodialysis (BMED) is a promising technique for upgrading traditional manufacturing procedures and achieving a circular economy. However, the industrial applications of BMED technology have been restricted by the large consumption of expensive bipolar membranes and the unmatching behavior between water splitting and ion migration. Herein, we proposed a novel asymmetric bipolar membrane electrodialysis (ABMED) to regulate the water splitting in the bipolar membrane and orientational ion migration in the electrodialysis (ED). It was found that the ABMED exhibited comparable performances to BMED for acid/base production when the area of the bipolar membrane was reduced to 50% of the monopolar membrane. The total process cost of ABMED was 0.78 $/kg NaOH, which is 21% lower than the BMED process. The asymmetric membrane design was capable to boost the water splitting in the bipolar membrane and to eliminate the concentration polarization in the ED process.     

Bipolar membrane electrodialysis for cleaner production of N-methylated glycine derivative amino acids

In this study, cleaner production of N-methylglycine (NMG), N,N-dimethylglycine (DMG), and N,N,N-trimethylglycine (TMG) with similar structures but different methylate groups was performed using bipolar membrane electrodialysis (BMED). The effects of the feed mass concentration and current density on the separation performance were intensively analysed in terms of the molecular size, molecular structure, ion concentration, and interaction between amino acids and membranes. The results indicated that the optimal recovery performance was achieved at a current density of 200 A/m² and feed mass concentration of 6%. Under the optimal conditions, the energy consumption and current efficiencies were 2.3 kWh/kg and 78% for NMG, 2.49 kWh/kg and 69.5% for DMG, and 3.52 kWh/kg and 39.6% for TMG, respectively. It was speculated a competition for water splitting occurs between the bipolar membranes and anion exchange membranes when BMED is used for the separation and purification of large-sized bioproducts.     

Bipolar membrane electrodialysis for clean production of L-10-camphorsulfonic acid: From laboratory to industrialization

In this study, bipolar membrane electrodialysis (BMED) was implemented for cleaner production of L-10-camphorsulfonic acid (L-CSA) to lower the environmental impact. Under the current density of 300–400 A/m² and feed salt concentration of 6–10 wt.%, the energy consumption and current efficiency were 2.24–2.70 kWh/kg and 20.89–29.5%, respectively. Positron annihilation lifetime spectroscopy, x-ray photoelectron spectroscopy with ion beam etching, and other characterizations were used to elucidate the transport behaviors of large-sized anions across the membranes. It was speculated that the large-sized camphor sulfonate ions were more likely to deposit on the surface of the anion-exchange membrane to form a deposition layer under a direct current electric field. The appearance of water splitting at this deposition layer would offset the water dissociation in the bipolar membrane. Nevertheless, the successful commissioning of industrial-scale stack proved the feasibility and sustainability of BMED technique for a closed loop L-CSA production.     

One-step conversion of sulfate lithium into high-purity lithium hydroxide crystals via bipolar membrane crystallization

To date, bipolar membrane electrodialysis (BMED) is being developed as a competitive technology for waste lithium-ion battery recovery. However, the purity and concentration of lithium hydroxide generated from a BMED plant could not meet the product criteria for ternary lithium batteries, thus requiring additional condensation, purification, evaporation, and crystallization procedures. Herein, bipolar membrane crystallization (BMC) was proposed for the one-step conversion of sulfate lithium into high-purity lithium hydroxide monohydrate crystals. By mediating a continuous saturated feedstock in the salt compartment, it is possible to convert Li₂SO₄ into 5+ mol/L LiOH at a current density higher than 500 A/m². Therefore, this unique design allows the production of 99.9% LiOH∙H₂O by taking the principle of water dissociation in the bipolar membrane and the simultaneous crystallization procedure. This proof-of-concept study proves the feasibility and competitiveness of the BMC for waste lithium recovery by abandoning the condensation and evaporation procedures.     

Multistage-batch bipolar membrane electrodialysis for base production from high-salinity wastewater

Bipolar membrane electrodialysis (BMED) is considered a state-of-the-art technology for the conversion of salts into acids and bases. However, the low concentration of base generated from a traditional BMED process may limit the viability of this technology for a large-scale application. Herein, we report an especially designed multistage-batch (two/three-stage-batch) BMED process to increase the base concentration by adjusting different volume ratios in the acid (V_acid), base (V_base), and salt compartments (V_salt). The findings indicated that performance of the two-stage-batch with a volume ratio of V_acid:V_base:V_salt = 1:1:5 was superior in comparison to the three-stage-batch with a volume ratio of V_acid:V_base:V_salt = 1:1:2. Besides, the base concentration could be further increased by exchanging the acid produced in the acid compartment with fresh water in the second stage-batch process. With the two-stage-batch BMED, the maximum concentration of the base can be obtained up to 3.40 mol∙L^–1, which was higher than the most reported base production by BMED. The low energy consumption and high current efficiency further authenticate that the designed process is reliable, cost-effective, and more productive to convert saline water into valuable industrial commodities.     

Membrane fouling caused by amino acid and calcium during bipolar membrane electrodialysis

BACKGROUND: Bipolar membrane electrodialysis (BMED) has been widely applied in the recovery/production of organic acids and in the treatment of wastewater containing ammonium sulfate, sodium nitrate, sodium acetate and ammonium nitrate. However, membrane fouling is still one of the major problems in the electrodialysis process. Since calcium and amino acid are present naturally in fermentation wastewater, this study was carried out to determine the effects of calcium and amino acid on membrane fouling when simulated fermentation wastewater containing ammonium sulfate was treated by BMED. RESULTS: Calcium formed a scale on the cation exchange membrane (CEM) surface in contact with the base cell, but this had no significant adverse effect on the BMED performance. Amino acid, however, caused CEM fouling of the inner membrane, which hampered the BMED process. The coexistence of calcium and amino acid aggravated the membrane fouling, as observed morphologically on the CEM surface on the base cell side. Elemental mapping analysis showed that the membrane foulant was composed of calcium hydroxide and amino acid. CONCLUSION: The CEM fouling caused by calcium and that due to amino acid, which were distributed differently on the membrane, had different effects on the BMED performance. The coexistence of amino acid and calcium deteriorated the CEM fouling during BMED. Copyright © 2008 Society of Chemical Industry     

含油废水的膜处理技术

膜分离法处理含油污水简单、高效且能耗低 ,合理选择膜和设计膜组件可以提高油脱除率 ,减小膜污染 ,增加处理量 ;油水分离的膜过程机理研究尚不成熟 ,岌待建立相关理论 ;分析了传统的膜分离技术及组件 ,指出双极旋转膜组件能够较好地强化膜过程 ,是一种极具发展潜力的含油污水处理方式。     

Transient Simulation of Hollow‐Fiber Membrane Filtration with Nonuniform Permeability Distribution

Transient simulation of filtration in hollow‐fiber membranes with nonuniform permeability distribution was conducted. The diversity of permeability distributions caused different initial flux and transmembrane pressure distributions. Manipulating the permeability distribution enables a hollow‐fiber membrane to achieve its maximum volumetric flow rate. During solid‐liquid separation, the inter‐adjustment between flux and cake distributions improved their uniformities simultaneously. The reciprocal of the volumetric flow rate of the membranes all increased linearly with water production. Severely nonuniform permeability distribution caused low water production. The numerical results could be applicable to account for the non‐ideal performance of industrial hollow‐fiber membrane modules.