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

人口增长将淡水需求增加到了临界水平。海水淡化有可能解决这个问题。然而，目前的技术并不具备可持续运营所需的效率。本项目的目标是开发两种新型的电化学海水淡化电池，用于高效率的苦咸水和海水淡化。新的海水淡化技术管理能量、水和溶解的盐，不同于现有的海水淡化方法。如果成功，这项技术有可能提供高效的海水淡化，以可持续地满足国家日益增长的淡水需求。拟议的研究将在两种新的海水淡化策略中使用铋(Bi)作为新的氯(Cl)储存电极。第一种策略是通过将铋作为氯离子存储电极和钠(Na)存储电极相结合来创建无膜海水淡化电池。这种电池可以储存和释放盐离子，同时储存和释放能量，从而将海水淡化所需的净能量降至最低。第二种策略是构建由铋和氯化铋电极组成的电渗析(ED)电池。与传统的ED电池相比，由于电极反应采用正向BiOCl氧化还原反应和反向BiOCl氧化还原反应，因此BiOClED电池的工作电压显著降低。建议的海水淡化电池的运行是基于电化学氧化还原反应，包括同时的电子和离子转移、离子存储和相变。与传统的海水淡化方法相比，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、循环性和氯离子在铋和氯化铋电极上的储存/释放能力的机理理解。这些知识对于以最小的能量投入提高海水淡化效率至关重要。如果成功，电化学海水淡化过程可以很容易地与各种其他电化学过程相结合，包括电化学水消毒和燃料和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智力优势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.