Smart Porous 3D Macrostructures of Graphene Oxide for Selective Removal and Transformation of Contaminants from Water

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Over 650 million people, including a large number of Canadian Northern and indigenous communities, do not have access to safe and clean water. Canada, among many other countries, has made a commitment to remove barriers against access to safe and clean water by 2030 within the United Nations Sustainable Development Goals framework. As such, point of use (POU) water treatment devices are alternatives for centralized water treatment systems in remote and sparsely populated areas, such as many of the Northern and indigenous communities that lack access to clean water. Although progress has been made in past years, POU devices still lack the required efficiency to replace centralized water treatment facilities. The scope of this research program is to investigate the possibility of using graphene oxide (GO), a novel carbon-based nanomaterial, to develop multifunctional and efficient POU devices. GO is self-assembled into highly porous 3D macrostructures (3DMs) similar to sponges. One major objective of the proposed research program is to understand the critical role of processing parameters on the properties of 3DMs such as specific surface area, mechanical properties and surface chemistry. Another major goal of this research program is to improve the mechanical properties of GO 3DMs so that they can withstand several regeneration and reuse cycles. Various types of cellulose nanocrystals (CNCs) will be used in conjunction with GO nanosheets to self-assemble them into hybrid 3DMs. The resulting mechanically robust 3DMs will be tested under realistic regeneration and reuse scenarios and their long term robustness will be evaluated. For regeneration, simple strategies available in any household such as use of weak acids (vinegar) will be investigated. Lack of contaminant selectivity is a major obstacle for commercial and large scale use of GO-based 3DMs for water treatment. 3DMs will be treated with components that selectively target contaminants of concern including oils and organic compounds such as pharmaceuticals and toxins, waterborne bacteria, heavy metals and micro- and nanoplastics. Apart from selectivity, this research program also aims to transform the removed contaminants into less harmful compounds. The 3DMs will be surface functionalized with chemical agents that convert oils and organic compounds into smaller and less harmful molecules, kill harmful waterborne bacteria, and interact with heavy metal ions to convert them into less harmful organometallic compounds. The results of this research program will help bring equity in access to safe and clean water to Canadian indigenous and Northern communities, as well as any community around the world with limited access to centralized water treatment facilities. The POU devices will also find applications in disaster relief scenarios where access to centralized water treatment facilities becomes restricted.