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Thermodynamics of ionic liquid solvents in gas purification and exfoliation mechanisms: molecular dynamics simulation and Monte Carlo calculations

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dc.contributorBao, Yuping
dc.contributorBara, J. E.
dc.contributorUnnikrishnan, Vinu U.
dc.contributorWujcik, Evan K.
dc.contributor.advisorTurner, C. Heath
dc.contributor.authorAbedini, Asghar
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.date.accessioned2018-12-14T18:11:45Z
dc.date.available2018-12-14T18:11:45Z
dc.date.issued2018
dc.descriptionElectronic Thesis or Dissertationen_US
dc.description.abstractDemand for green sources of energy is increasing due to the critical need to decrease greenhouse gas emissions. This research involved different approaches for reducing CO2 emission to the atmosphere. In the first study, the exfoliation of bismuth telluride (Bi2Te3) as a well-know thermoelectric (TE) material was investigated. In the literature, it has been experimentally and computationally proven that producing a thinner layer of Bi2Te3 increases the “figure of merit” by reducing the thermal conductivity and enhancing the electrical conductivity. A liquid-phase exfoliation technique is one of the potential approaches to exfoliate Bi2Te3. In my simulation work, different types of imidazolium-based ionic liquids (ILs) were screened to find the most efficient exfoliant, by first considering the value of the solid surface energy and surface tension of the applied liquids. We found that [Tf2N-]-based ionic liquids are relatively effective at enhancing the exfoliation, and this performance can be correlated to the unique molecular-level solvation structures developed at the Bi2Te3 surfaces. In the second study, I modeled CO2 separation during typical pre-combustion and post-combustion condition using a novel IL + polymer membrane material. This work was inspired by recent experimental findings from the Bara group at UA. The new class of materials was generated by adding ionic liquid molecules to the backbone of polymers while using (pyromellitic dianhydride) PMDA as an organic ligand. For the first time, these polymers, “ionic polyimides” (i-IPs), were computationally investigated as a potential membrane for CO2 separation. The presence of the IL significantly displaces the CO2 molecules from the ligand nitrogen sites in the neat i-IP to the imidazolium rings in the i-IP + IL composite. These molecular details can provide critical information for the experimental design of highly selective i-IP materials, as well as provide additional guidance for the interpretation of simulated adsorption systems. It is found that the 50% IL addition can increase CO2/CH4 selectivity by 16% in [BF4-]-based and by 36% in [PF6-]-based structures. While the [BF4-]-based system shows higher CO2/CH4 selectivity, the [Tf2N-]-based system shows higher CO2/N2 gas separation performance. These findings are exemplified by high gas solubility of [PF6-]-based structures, which also compensate to a correlated larger theoretical surface area.en_US
dc.format.extent155 p.
dc.format.mediumelectronic
dc.format.mimetypeapplication/pdf
dc.identifier.otheru0015_0000001_0003072
dc.identifier.otherAbedini_alatus_0004D_13530
dc.identifier.urihttp://ir.ua.edu/handle/123456789/5204
dc.languageEnglish
dc.language.isoen_US
dc.publisherUniversity of Alabama Libraries
dc.relation.hasversionborn digital
dc.relation.ispartofThe University of Alabama Electronic Theses and Dissertations
dc.relation.ispartofThe University of Alabama Libraries Digital Collections
dc.rightsAll rights reserved by the author unless otherwise indicated.en_US
dc.subjectChemical engineering
dc.titleThermodynamics of ionic liquid solvents in gas purification and exfoliation mechanisms: molecular dynamics simulation and Monte Carlo calculationsen_US
dc.typethesis
dc.typetext
etdms.degree.departmentUniversity of Alabama. Department of Chemical and Biological Engineering
etdms.degree.disciplineChemical & Biological Engineering
etdms.degree.grantorThe University of Alabama
etdms.degree.leveldoctoral
etdms.degree.namePh.D.

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