ERI: Carbon electrodes with controlled surface topology for desalination and water disinfection.

This is an NSF Engineering Research Initiation award. Water scarcity is one of the most significant challenges facing the world today. An estimated 4.0 billion people currently experience severe water scarcity during at least 1 month a year. Measures to alleviate water shortages, such as water conservation and improved catchment and distribution systems, are important, but do not increase existing freshwater resources. Alone these methods are insufficient in coping with rising water demand which is further intensified by increasing population, agricultural needs, and industrialization. The only methods to increase freshwater supply are limited to water reuse and desalination, with the latter offering a seemingly unlimited supply. In addition to water scarcity, access to clean drinking water is a global challenge. Unfortunately, waterborne diseases persist in developing countries and are one of the leading causes of death. Continued research into technologies that can simultaneously desalinate and disinfect water is a vital area of research, which has led to the emergence of capacitive deionization (CDI). CDI systems desalinate salty feed solutions by electrostatically adsorbing ionic species to a pair of oppositely charged electrodes. CDI systems can also disinfect contaminated water sources if harmful microorganisms possess a net surface charge. For long-term full-scale CDI systems, the electrodes can be one of the largest expenses in terms of capital costs and operating costs. This project will investigate a sustainable approach to fabricating ultra-low-cost CDI electrodes by utilizing wasted food (i.e. – bread). The broader impact of the project may enhance the development of sustainable freshwater drinking supplies. Furthermore, the project will enable the building of a sustainable education and training system for undergraduate researchers at Saint Vincent College and for high school students from underserved groups. The vast majority of CDI research has focused on tailoring the nanostructure of the electrode material to generate high surface area. This was primarily done to maximize the amount of ionic species that can be adsorbed to the electrode surfaces during the desalination process. Preliminary work has discovered that intact natural materials (e.g. mangrove roots and wasted bread) can serve as excellent precursors to generating freestanding CDI electrodes. The micro-features (100’s of microns) of these natural materials can be preserved through pyrolysis and offer major advantages when integrated into CDI systems, such as low-resistance pathways for water transport. The project’s objective is to study the potential effects micro-features may have on the performance of CDI electrodes in desalination systems and disinfection systems. The project’s objectives are to: (1) Demonstrate that carbon electrodes can be fabricated with controlled surface topology on the order of 100’s of microns using natural materials as feedstocks and (2) Understand the dependence of desalination performance and disinfection performance on electrode surface topology in a CDI system. The intellectual merit of the work will lead to new techniques for generating carbon electrodes with controlled microstructures. Importantly, the nature of these techniques will be inexpensive and realizable in primarily undergraduate institutions. 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.