Cellulose-based Scaffolds for Lithium Capturing

Thesis (Master's)--University of Washington, 2022Cellulose, a naturally occurring and most abundant bio-based polymer on earth. It offersflexibility when it comes to potential applications in various industries and has been continued to be modified to fit such demands. Obtaining cellulose from different sources, or processing cellulose to alter its chemical structure are strategies that offer control of the final material performance and can lead to vastly different properties. Ultimately, cellulose is a material that is both widely available and capable of fulfilling the needs of numerous markets and industries. One of the key advantages of cellulose is its hierarchical structure that gives rise to exceptional mechanical properties, among other features. Utilizing different synthesis and processing methods, different types of nanocellulose can be prepared. These include crystalline nanocellulose, cellulose nanofibrils and bacterial cellulose. Here we explore the potential use of nanocellulose as a matrix material for nanocomposite membranes aiming to capture Li ions from seawater. We choose nanocellulose as it combines high strength and porosity and is derived from renewable resources. While cellulose itself is not selective for Li ions, non-toxic Hydrogen Titania Oxide (HTO) nanoparticles serving as a filler for the nanocomposite membranes presented in this work offer Li selectivity, and can be used in conjunction with nanocellulose to form a proper platform for Li capturing. Here, we prepare several different cellulose scaffolds and compare them as matrix materials for HTO nanoparticles with the key criteria for our evaluation being the structural stability and reusability of the membrane. Matrix materials studied include crystalline and nanofibril hydrogels along with bacterial cellulose films that have been either retained in their original state or freeze-dried to increase porosity