Dissertation
Studies on gas-separation performance and antibacterial activity of one- and two-dimensional nanomaterials
Doctor of Philosophy (Ph.D.), Drexel University
Sep 2026
DOI:
https://doi.org/10.17918/00011590
Abstract
The properties and performance of low-dimensional nanomaterials are strongly influenced by their composition, structure, and processing. This dissertation explores these relationships through the synthesis and application of one- and two-dimensional nanomaterials, including Ti₃C₂T_x MXene, double-transition-metal MAX phases, and one-dimensional titanate nanofilaments, with the goal of developing materials with tailored gas-separation and antibacterial properties. Progress in gas-separation membranes is limited by several challenges, including the permeability-selectivity trade-off in polymeric membranes and defects arising from nanosheet stacking in laminar two-dimensional membranes. This dissertation addresses these challenges using Ti₃C₂T_x MXene in two distinct membrane architectures. First, MXene nanosheets are surface-functionalized and incorporated into a glassy polyimide to strengthen interactions between the filler and polymer chains. The improved interfacial compatibility and dispersion lead to mixed-matrix membranes with more than twofold increases in both CO₂ permeability and CO₂/CH₄ selectivity compared with the pristine membrane. Second, MXene is combined with graphene oxide (GO) on an anodic aluminum oxide (AAO) support to form a laminar architecture. Incorporating GO reduces interflake defects and interlayer spacing while promoting more ordered, slit-like nanochannels for molecular sieving. The optimized MXene/GO membranes yields an H₂ permeance of 2681.6 GPU and an H₂/CO₂ selectivity of 536.3, demonstrating that control over nanosheet stacking and interfacial structure can simultaneously enhance permeance and selectivity. In addition to the Ti₃C₂T_x applications, this dissertation investigates the synthesis of novel Mo₂NbAlC₂ double-transition-metal MAX phase by systematically varying sintering temperatures, dwell times, Mo/Nb ratio, and carbon content. The results identify the Mo/Nb ratio and dwell time as the dominant variables governing the selective formation of the target 312 phase and its 413 counterpart, Mo₂Nb₂AlC₃. Finally, quantum-confined, one-dimensional lepidocrocite titanate nanofilaments are evaluated for antibacterial activity against E. coli, B. subtilis, and L. innocua. The nanofilaments achieve high bacterial inactivation under both ambient light and dark conditions, demonstrating that their antibacterial activity does not require light activation. Flow cytometry, reactive oxygen species assays, electron microscopy, and ion-release measurements reveal that the activity arises primarily from direct physical disruption of bacterial membranes rather than photochemically generated species or dissolved Ti ions. These findings establish one-dimensional titanate nanofilaments as a promising platform for light-independent antibacterial applications.
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Details
- Title
- Studies on gas-separation performance and antibacterial activity of one- and two-dimensional nanomaterials
- Creators
- Mohammad Mozafari
- Contributors
- Masoud Soroush (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University
- Number of pages
- xxii, 172 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Nick Howley College of Engineering and Computing; Chemical and Biological Engineering; School of Engineering; Drexel University
- Other Identifier
- 991022233844704721