ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- All Subjects: chemical engineering
Description
Freshwater as the resource for the survival of humans and all lives on earth is very precious but scarce. The shortage of the original freshwater resources and the interfering activities by human and other natural factors form this issue together. To reduce the water supply pressure and deterioration of freshwater systems (for example, river, wetland, and groundwater), the quantity-increase and the quality-increase strategies should be implemented at the same time. Therefore, corresponding membrane technologies have been developed to achieve water purification with high efficiency and low cost. For desalinating seawater and other types of saline water, pervaporation has been proved that has the potential to complete desalination with salt rejection rate over 99 % when dealing with high salinity water that reverse osmosis (RO) cannot handle. In this dissertation, except the discussion of commonly used materials to synthesize pervaporation membranes, two types of novel pervaporation desalination membranes (nanophotonic-enhanced membrane and free-standing sulfonated membrane) have been presented and discussed. The novel membranes were tested to see the potential of pervaporation to desalinate seawater and saline water with more complex ionic composition, and the possibility of achieving zero liquid discharge in the desalination field when having pervaporation as the assistance. For mitigating polluted water that is caused by human activities, especially agricultural activities, electrodialysis is an effective method to remove specific ions from water, and it does not require extra chemical cost or regeneration. A type of anion exchange membranes inspired by ion exchange resins was synthesized and tested, and the performance on nitrate removal has been evaluated in this dissertation.
ContributorsLi, Yusi (Author) / Lind, Mary Laura (Thesis advisor) / Perreault, Francois (Thesis advisor) / Forzani, Erica (Committee member) / Seo, S. Eileen (Committee member) / Walker, W. Shane (Committee member) / Arizona State University (Publisher)
Created2023
Description
Lithium-ion and lithium-metal batteries represent a predominant energy storage solution with the potential to address the impending global energy crisis arising from limited non-renewable resources. However, these batteries face significant safety challenges that hinder their commercialization. The conventional polymeric separators and electrolytes have poor thermal stability and fireproof properties making them prone to thermal runaway that causes fire hazards and explosions when the battery is subjected to extreme operating conditions. To address this issue, various materials have been investigated for their use as separators. However, polymeric, and pure inorganic material-based separators have a trade-off between safety and electrochemical performance. This is where zeolites emerge as a promising solution, offering favorable thermal and electrochemical characteristics. The zeolites are coated onto the cathode as a separator using the scalable blade coating method. These separators are non-flammable with high thermal stability and electrolyte wettability. Furthermore, the presence of intracrystalline pores helps in homogenizing the Li-ion flux at anode resulting in improved electrochemical performance. This research delves into the preparation of zeolite separators using a commercial zeolite and lab-scale zeolite to study their safety and electrochemical performance in lithium-ion batteries. At low C-rates, both zeolites exhibited excellent capacity retention and capacity density displaying their potential to advance high-performance safe lithium-ion batteries. The commercial zeolite has demonstrated remarkable capacity retention and good performance in terms of charge and discharge cycles, as well as stability. This makes it a valuable resource for the scaling up of electrode-coated separator technology.
Furthermore, the previous study demonstrated the superior electrochemical performance of plate silicalite separator (also a lab-made zeolite) with both lithium-ion and lithium-metal batteries. However, the process of scaling up and achieving precise control over plate silicalite particle size, and morphology using the existing synthesis procedure has proven challenging. Thus, the modification of process conditions is studied to enhance control over particle size, aspect ratio, and yield to facilitate a more efficient scaling-up process. Incorporation of stirring during the crystallization phase enhanced yield and uniformity of particle size. Also, the increase in temperature and time of crystallization enlarged the particles but did not show any significant improvement in the aspect ratio of the particles.
ContributorsNalam, Ramasai Dharani Harika (Author) / Lin, Jerry (Thesis advisor) / Emady, Heather (Committee member) / Seo, S. Eileen (Committee member) / Arizona State University (Publisher)
Created2023
Description
The properties of block polymers (BPs) are intricately coupled to the dynamic and rich nature of the nanostructured assemblies which result from the phase separation between blocks. The introduction of strong secondary forces, such as electrostatics and hydrogen bonding, into block polymers greatly influences their self-assembly behavior, and therefore affects their physical and electrochemical properties often in non-trivial ways. The recent surge of work expanding scientific understanding of complex spherical packing in block polymers (BPs) has unlocked new design space for the development of advanced soft materials. The continuous matrix phase which percolates throughout spherical morphologies is ideal for many applications involving transport of ions or other small molecules. Thus, determining the accessible parameter range of such morphologies is desirable. Bulk zwitterion-containing BPs hold great potential within the realm of electroactive materials while remaining relatively untapped. In this work, architecturally and compositionally asymmetric diblock polymers were prepared with the majority block having zwitterions tethered to side chain termini at different ratios. Thermally reversible Frank-Kasper phases are observed in multiple samples with significant signs of kinetic arrest and influence. The kinetic influences are validated and described by the temperature-dependent static permittivity. Polyzwitterions combine the attractive features of zwitterions with the mechanical support and processability of polymeric materials. Among these attractive features is a potential for superior permittivity which is limited by the propensity of zwitterions to pack into strongly associating structures. Block polymer self-assembly embodies a plethora of packing frustration opportunities for optimizing polyzwitterion permittivity. The capabilities of this novel approach are revealed here, where the permittivity of a polyzwitterionic block is enhanced to a level comparable to that of pure liquid zwitterions near room temperature (εs ~ 250), but with less than a third the zwitterion concentration. The mechanistic source of permittivity enhancement from a single zwitterion-tethered block polymer is realized deductively through a series of thermal pathways and control sample experiments. Tethered zwitterions within the mixed block interface are frustrated when subject to segmental segregation under sufficient interfacial tension and packing while non-interfacial zwitterions contribute very little to permittivity, highlighting the potential for improvement by several fold.
ContributorsGrim, Bradley James (Author) / Green, Matthew (Thesis advisor) / Long, Timothy (Committee member) / Richert, Ranko (Committee member) / Jin, Kailong (Committee member) / Seo, S. Eileen (Committee member) / Arizona State University (Publisher)
Created2024
Description
Crystalline polymeric materials play an increasingly important role in daily life.Understanding and controlling the development of crystallinity is integral to improving the
performance of crystalline polymers in packaging, drug delivery, water treatment, gas
separations, and many other industries. Herein, fluorescence and Raman spectroscopy have
been applied for the first time to study the crystallinity of polymers, including traditional
semicrystalline thermoplastics and covalent organic frameworks (COFs; an emerging class
of crystalline polymers with highly ordered pore structures). On one hand, by incorporating
a fluorescent dye segment into a semicrystalline polymer matrix, it is feasible to accurately
monitor its crystallization and melting. The flexibility of dye incorporation allows for new
fundamental insights into polymer crystallization in the bulk and at/near interfaces that
may otherwise be out of reach for established techniques like differential scanning
calorimetry (DSC). On the other hand, Raman spectroscopy has been identified as a
technique sensitive to the crystallinity of COFs and applied alongside well-established
characterization techniques (X-ray diffraction and N2 adsorption) to monitor the
crystallization of COFs during synthesis. This has enabled careful control of COF
crystallinity during solvothermal synthesis for improved application in the field of drug
delivery. The monitoring of COF crystallinity has been extended to more complex film
geometries produced by interfacial polymerization. The high molecular sieving potential
of COFs remains out of reach in part due to a lack of understanding of the interplay between
crystallinity, crystallite orientation, and filtration performance. A careful study of these
relationships is suggested for future work to provide key insight toward applying COFs as
molecular sieving materials in water treatment and other separation applications.
ContributorsNile, Richard Gabriel (Author) / Jin, Kailong (Thesis advisor) / Lin, Jerry (Committee member) / Acharya, Abhinav (Committee member) / Seo, S. Eileen (Committee member) / Chen, Xiangfan (Committee member) / Arizona State University (Publisher)
Created2024