New Strategies for Electrochemical Water Desalination Using Bi as a Cl-Storage Electrode

人口增长使对淡水的需求增加到临界水平。海水淡化有可能解决这一问题。然而，目前的技术不具备可持续运营所需的效率。该项目的目标是开发两种新型电化学脱盐电池，用于高效率的苦咸水和海水脱盐。这种新型的海水淡化技术与现有的海水淡化方法不同，可以管理能量、水和溶解盐。如果成功，这项技术有可能提供有效的海水淡化，以可持续地满足国家对淡水不断增长的需求。拟议的研究将使用铋（Bi）作为两种新型海水淡化策略中的新型氯化物（Cl）存储电极。第一种策略是通过将Bi作为Cl存储电极与钠（Na）存储电极组合来创建无膜脱盐电池。这种电池可以存储和释放盐离子，同时存储和释放能量，从而最大限度地减少脱盐的净能量需求。第二种策略是构建由Bi和BiOCl电极组成的电渗析（艾德）池。与传统的艾德电池相比，Bi/BiOCl艾德电池的工作电压可以显著降低，因为正向Bi氯化和反向BiOCl脱氯氧化还原反应被用作电极反应。所提出的脱盐电池的操作是基于涉及同时的电子和离子转移、离子存储和相变的电化学氧化还原反应。与传统的脱盐方法相比，这是一种非常新颖的方法。拟议的研究将建立原子水平的动力学，循环性，和容量的Cl-存储/释放的Bi和BiOCl电极的机械理解。这些知识对于以最小的能量输入提高脱盐效率至关重要。如果成功，电化学脱盐过程可以很容易地与其他各种电化学过程集成，包括电化学水消毒和燃料及其他化学品的电化学生产。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Population growth has increased demand for freshwater to critical levels. Desalination of seawater has the potential to address this issue. However, current technology does not have the efficiency needed for sustainable operation. The goal of this project is to develop two types of novel electrochemical desalination cells for highly efficient desalination of brackish and seawater. The novel desalination technology manages energy, water, and dissolved salts different from existing desalination methods. If successful, this technology has the potential to provide efficient desalination to sustainably meet the increasing demands for freshwater in the Nation.The proposed research will use bismuth (Bi) as a new chloride (Cl)-storage electrode in two novel desalination strategies. The first strategy is to create a membrane-free desalination battery by combining Bi as a Cl-storage electrode with a sodium (Na)-storage electrode. This battery can store and release salt ions while simultaneously storing and releasing energy, thus minimizing the net energy requirement for desalination. The second strategy is to construct an electrodialysis (ED) cell composed of Bi and BiOCl electrodes. Compared to conventional ED cells, the operating voltage of the Bi/BiOCl ED cell can be markedly lowered because the forward Bi chlorination and reverse BiOCl dechlorination redox reactions are used as the electrode reactions. The operation of the proposed desalination cells is based on electrochemical redox reactions involving simultaneous electron and ion transfer, ion storage, and phase transformations. This is a highly novel approach compared to conventional desalination methods. The proposed research will establish atomic level mechanistic understanding of kinetics, cyclability, and capacity of Cl-storage/release on the Bi and BiOCl electrodes. This knowledge is essential to enhance desalination efficiency with a minimum energy input. If successful, the electrochemical desalination processes can be easily integrated with various other electrochemical processes, including electrochemical water disinfection and electrochemical production of fuels and other chemicals.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.