Skip to Main Content
Frequently Asked Questions
Submit an ETD
Global Search Box
Need Help?
Keyword Search
Participating Institutions
Advanced Search
School Logo
Files
File List
PhD Dissertation-VijwaniHema-new.pdf (7.52 MB)
ETD Abstract Container
Abstract Header
Hierarchical Porous Structures with Aligned Carbon Nanotubes as Efficient Adsorbents and Metal-Catalyst Supports
Author Info
Vijwani, Hema
ORCID® Identifier
http://orcid.org/0000-0002-8750-2526
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=wright1433350549
Abstract Details
Year and Degree
2015, Doctor of Philosophy (PhD), Wright State University, Engineering PhD.
Abstract
The overall goal of this study is two-fold: synthesis of multiscale nanostructures by growing aligned carbon nanotubes on porous foam substrates and investigation of their applicability as adsorbents and catalyst supports for environmental remediation applications. High purity, vertically-aligned arrays of carbon nanotubes (CNT) are grown on open-cell interconnected porous carbon foams by pre-activating them with an oxide buffer layer followed by chemical vapor deposition (CVD). This type of hierarchical morphology provides the capability of increasing surface area by several orders of magnitude, while tuning its morphology for targeted applications. Analytical models are also proposed in this study for specific surface area calculations, those agree well with the experimental measurements. These hierarchical carbon materials are seen to be powerful adsorbents of aqueous pollutants such as methylene blue dye. Their monolayer adsorption capacities correlate very well with the total CNT surface area determined from analytical models and with BET measurements, indicating full utilization of the nanotube surfaces. The hierarchical structures can also serve as base supports for attachment of metal nanoparticle catalysts. The catalysts investigated in this study are metallic palladium (Pd), oxidized palladium (PdO), and silver-palladium (Ag-Pd) nanoparticles combination. These are suitable for a variety of industrial applications such as hydrocarbon conversion, hydrogen storage, fuel cell electrodes and pollutant degradation. The current architecture allows synthesis of highly active catalyst structures utilizing very small quantities of precious metal that make the catalyst component significantly lighter and more compact than conventional systems. Detailed characterization of structure and surface chemical states of these nano-catalysts have been performed and their catalytic activities are tested by measuring the degradation kinetics of organic contaminants via bench-scale experiments. Catalytic degradation of atrazine, an emerging problematic contaminant, was quantified using high-performance liquid chromatography. Among Pd, PdO, and Ag-Pd nanoparticles, PdO in the presence of hydrogen was seen to provide the most rapid reaction rate. These nanocatalysts also enable rapid degradation of chlorinated hydrocarbons such as trichloroethylene and trichloroethane quantified using head-space gas chromatography, with PdO providing the fastest kinetic route. Durability tests indicated that the nano-particles and nanotubes are robust, and remain attached to the base support after long periods of rapid rotation in water. These results imply that such materials can provide compact and powerful surface active materials in future applications such as adsorbents, catalysts, porous electrodes, and energy storage devices.
Committee
Sharmila Mukhopadhyay, Ph.D. (Advisor)
Mallikarjuna Nadagouda, Ph.D. (Committee Member)
Mark Goltz, Ph.D. (Committee Member)
Amir Farajian, Ph.D. (Committee Member)
Hong Huang, Ph.D. (Committee Member)
Pages
225 p.
Subject Headings
Engineering
;
Environmental Studies
;
Materials Science
;
Nanoscience
;
Nanotechnology
Keywords
Carbon nanotubes, Hierarchical Structures, Porous materials, Catalysts, Palladium, Silver, Nanoparticles, Bimetallic, Aligned CNT, CVD, XPS, Water Purification, Adsorption, Dechlorination, Degradation, Methylene blue, Trichloroethylene, Atrazine
Recommended Citations
Refworks
EndNote
RIS
Mendeley
Citations
Vijwani, H. (2015).
Hierarchical Porous Structures with Aligned Carbon Nanotubes as Efficient Adsorbents and Metal-Catalyst Supports
[Doctoral dissertation, Wright State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=wright1433350549
APA Style (7th edition)
Vijwani, Hema.
Hierarchical Porous Structures with Aligned Carbon Nanotubes as Efficient Adsorbents and Metal-Catalyst Supports.
2015. Wright State University, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=wright1433350549.
MLA Style (8th edition)
Vijwani, Hema. "Hierarchical Porous Structures with Aligned Carbon Nanotubes as Efficient Adsorbents and Metal-Catalyst Supports." Doctoral dissertation, Wright State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1433350549
Chicago Manual of Style (17th edition)
Abstract Footer
Document number:
wright1433350549
Download Count:
1,141
Copyright Info
© 2015, all rights reserved.
This open access ETD is published by Wright State University and OhioLINK.