Base Stable Bipolar Membranes with Electronically Conductive Interlayers for Environmental Applications

1604857FarrellMembrane系统在许多环境工程科学解决方案中越来越适用。本研究的目标是开发适合于环境应用的双极膜。双极膜是一项技术奇迹，具有与晶体管相似的pn结。这一过程将从水中去除盐，并将消除酸和碱用于离子交换再生，从而消除公共供水中盐的主要来源。虽然双极膜已经商业化20多年了，但由于商业化膜的局限性，它们并没有得到广泛的应用。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水分解所需的电压来改进。为碱性燃料电池开发的膜在高pH值下表现出优异的稳定性，可能适合生产用于环境应用的双极膜。在双极膜中心用导电中间层代替催化剂层可以减小p-n结的宽度并降低低电流密度下的水分裂电压。本研究将探讨在双极膜中使用高度稳定的聚联苯烷基阴离子交换膜和导电中间层。仅施加1伏的极化，双极膜就能将水分解成H+和OH-离子，其速率比散装水的速率高出7个数量级以上。尽管自1977年以来，双极膜已经商业化，但尚未获得广泛的工业应用。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，药物的回收和纯化，果汁的脱酸，以及能量储存和转换。双极膜广泛应用的两个障碍是强碱阴离子交换膜在碱性条件下的低稳定性和市售膜没有针对许多潜在应用的要求进行优化。研究人员假设，使用碱性燃料电池用的碱性稳定氢氧化物导电膜可以改善双极膜阴离子交换组分的碱稳定性。此外，我们提出一种具有导电层间区域的新型双极膜将在各种工业应用中有用，其中市售膜不适合。这里提出的研究将开发具有导电层间区域的碱性稳定双极膜，适用于水处理应用。除了科学上的影响，这项研究将生产更好的双极膜，这将在各种各样的应用中有用。双极膜能产生最大影响的领域是水处理。双极膜电渗析既可用于淡化水，也可用于提供水处理应用中常用的酸和碱，如：离子交换再生、混凝、阻垢、脱碳和颗粒软化。在水处理中取消酸和碱的使用将减轻干旱地区地下水和其他公共饮用水供应中盐积累的问题。该项目将支持1名博士生和数名本科生的培养和发展。此外，CONACyT项目支持的墨西哥博士后学者也将参与本研究。最后，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基础课程。

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.