Base Stable Bipolar Membranes with Electronically Conductive Interlayers for Environmental Applications

1604857 Farrell膜系统在许多环境工程科学解决方案中的适用性越来越强。本研究的目标是开发适用于环境应用的双极膜。双极膜是一项技术奇迹，它的p-n结类似于晶体管中的那些结。这一过程将去除水中的盐，并将消除用于离子交换再生的酸和碱，从而消除公共供水中的一个主要盐源。尽管双极膜已经商业化20多年，但由于市场上可获得的膜的限制，它们还没有得到广泛的使用。商业上可用的双极膜不太适合环境应用，可以通过提高其在高pH溶液中的稳定性和降低在低电流密度下分解水所需的电压来改善。为碱性燃料电池开发的膜在高pH值下表现出极高的稳定性，可能适合于生产环境应用的双极膜。在双极膜中心用导电中间层代替催化层，可以减小p-n结的宽度，并在低电流密度下降低分水电压。这项研究将探索用于双极膜的高度稳定的聚(联苯亚烷基)阴离子交换膜和导电中间层的使用。只需1伏的外加极化，双极膜就可以将水分解为H+和OH-离子，其速率比散装水中的速率高出7个数量级以上。尽管双极膜自1977年开始商业化，但尚未得到广泛的工业应用。双极膜已经在实验室和中试规模上进行了广泛的应用研究，包括：从盐溶液中生产无机酸，从发酵液中回收有机酸，生化过程中的pH控制，药物的回收和提纯，果汁的脱酸，以及能量储存和转换。双极膜更广泛使用的两个障碍是强碱性阴离子交换膜在碱性条件下的低稳定性，以及商业上可用的膜没有针对许多潜在应用的要求进行优化。PI假设，使用为碱性燃料电池开发的碱性稳定氢氧化物导电膜，可以改善双极膜的阴离子交换成分的碱稳定性。此外，我们还提出了一种新型的具有电子导电层间区的双极膜将在商业上的膜不适合的各种工业应用中使用。本文提出的研究将开发具有电子导电层间区的碱性稳定的双极膜，适用于水处理应用。除了这项研究的科学影响外，还将生产出更好的双极膜，这将在广泛的应用中发挥作用。双极膜能够产生最大影响的领域是水处理。双极膜电渗析可用于淡化水和提供水处理应用中常用的酸和碱，例如：离子交换再生、混凝、阻垢、脱碳和球团软化。在水处理中不再使用酸和碱，将缓解干旱地区地下水和其他公共饮用水供应中的盐分积累问题。该项目将支持一名博士生和几名本科生的培养和发展。此外，在CONACyT项目的支持下，来自墨西哥的博士后学者将被纳入这项研究。最后，一项教育和多样性计划将侧重于从代表性不足的群体中招收学生，并将研究成果纳入目前正在教授的电化学课的基础。

1604857FarrellMembrane systems are gaining in there applicability to many environmental engineering science solutions. The goal of this research is to develop bipolar membranes suitable for use in environmental applications. Bipolar membranes are a technological marvel and have p-n junctions similar to those in transistors. This process will remove salt from the water and will eliminate the use of acids and bases for ion exchange regeneration, thereby eliminating a major source of salts in public water supplies.Although bipolar membranes have been commercially available for more than 20 years, they have not gained widespread usage due to the limitations of commercially available membranes. Commercially available bipolar membranes are not well-suited for environmental applications, and can be improved by increasing their stability in high pH solutions and decreasing the voltage required for water splitting at low current densities. Membranes developed for alkaline fuel cells have shown exceptional stability at high pH values and may be suitable for producing bipolar membranes for environmental applications. Replacing the catalyst layer with an electrically conductive interlayer in the center of a bipolar membrane may decrease the width of the p-n junction and decrease the water splitting voltage at low current densities. This research will investigate the use of highly stable poly(biphenyl alkylene) anion exchange membranes and electrically conductive interlayers for use in bipolar membranes. With only 1 volt of applied polarization, bipolar membranes can split water into H+ and OH- ions at rates that are more than 7 orders of magnitude greater than the rate in bulk water. Despite their commercial availability since 1977, bipolar membranes have not attained widespread industrial use. Bipolar membranes have been studied at the laboratory and pilot scale for a wide variety of applications, including: production of mineral acids from salt solutions, recovery of organic acids from fermentation broths, pH control in biochemical processes, recovery and purification of pharmaceuticals, de-acidification of fruit juices, and energy storage and conversion. Two impediments to greater use of bipolar membranes are the low stability of strong-base anion exchange membranes under alkaline conditions and that commercially available membranes are not optimized for the requirements of many potential applications. The PIs hypothesize that the base stability of the anion exchange component of bipolar membranes can be improved using alkaline stable hydroxide conducting membranes developed for use in alkaline fuel cells. Additionally, we propose that a new type of bipolar membranes with an electronically conductive interlayer region will be useful in a variety of industrial applications where commercially available membranes are ill-suited. The research proposed here will develop alkaline stable bipolar membranes with electronically conducting interlayer regions that are suitable for use in water treatment applications. Aside from the scientific impact of this research will be the production of better bipolar membranes that will be useful in a wide variety of applications. The area where bipolar membranes can make the biggest impact is in water treatment. Bipolar membrane electrodialysis can be used to both desalinate water and to provide the acid and bases that are commonly used in water treatment applications, such as: ion exchange regeneration, coagulation, scale inhibition, decarbonation and pellet softening. Eliminating the use of acids and bases in water treatment will alleviate the problem of salt accumulation in groundwater and other public drinking water supplies in arid regions. The project will support the training and development of one doctoral student and several undergraduate students. In addition, post-doctoral scholars from Mexico supported by the CONACyT program will be integrated in this research. Finally, an education and diversity plan will focus on recruiting students from under-represented groups and integration of research results into the Fundamentals of Electrochemistry Class that is currently being taught.