Toward Sustainable Water Purification Using Carbon Electrodes Derived from Intact Plant Tissue and Food Waste

Meeting the water demands of a growing global population is one of the world’s “grand challenges”. To increase freshwater supply, many areas of the world generate drinking water by desalination of brackish water and seawater. In resource-rich regions, technologies such as reverse osmosis and thermal distillation are feasible solutions for desalination. However, the development

of more cost-effective and energy-efficient technologies remains an important area of research, especially for areas without easy technology access or financial resources, which has led to the development of capacitive deionization (CDI). CDI desalinates a salty feed solution by

electrostatically adsorbing ionic species to a pair of oppositely charged electrodes. When considering that the only essential operating components for CDI are a pair of electrodes and a low-voltage power supply, water desalination in resource-starved environments can be envisioned as a potential practical solution. In this work, we used the intact natural architecture of specific

plant-derived and wasted-derived materials to develop freestanding CDI electrodes with ultra-high hydraulic permeability and competitive desalination performances in comparison to common CDI electrodes. Importantly, our plant/waste-derived electrodes did not require additional materials (current collectors, binders, conductive additives) which are typically necessary for common CDI

electrode fabrication. We also developed a sustainable technique for electrode fabrication that does not require the use of common laboratory equipment and that could be deployed in developing countries with low-financial resources. We further expanded the scope of our water purification techniques with waste-derived electrodes to address pathogenic organisms in water. Unfortunately,

waterborne diseases are one of the leading causes of death in many developing regions and the development of low-cost disinfection methods that feasible in such regions is highly important. Lastly, we investigated mechanisms of naturally occurring desalination in mangrove plants as a potential avenue to inspire fouling-resistant membranes for reverse osmosis systems. These findings will have impacts in a diversity of areas such as plant biology, desalination, water disinfection, and sustainable engineering.