Asphaltene Self-Assembly

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dc.contributor.advisor Peter K. Kipatrick, Committee Chair en_US
dc.contributor.advisor Jan Genzer, Committee Member en_US
dc.contributor.advisor Orlin D. Velev, Committee Member en_US
dc.contributor.advisor Saad A. Khan, Committee Member en_US Verruto, Vincent J. en_US 2010-04-02T18:25:33Z 2010-04-02T18:25:33Z 2008-11-07 en_US
dc.identifier.other etd-08122008-174155 en_US
dc.description.abstract Despite a strong push for alternative energy, fossil fuels remain an important energy source given an ever-increasing global energy demand. As crude oil prices continue to soar, petroleum producers and refiners are looking to “unconventional†crudes, such as bitumen and heavy crude oils, to meet their needs. Unlike light-sweet “conventional†feedstocks, heavy crudes are often rich in a fraction that is characteristically polydisperse, of high-MW, polyaromatic, polar, and surface-active. Consequently, asphaltenes present expensive challenges associated with aggregation, flocculation, precipitation, deposition, and emulsion stabilization. The scope of the work here focuses on two important aspects of asphaltene self-assembly: bulk phase aggregation and interfacial film formation. Using small-angle neutron scattering (SANS) we expand the description of these aggregates beyond their size (~50-100 Å), shape (discoidal), and degree of solvent entrainment (30-50% by volume), to also include the entrained solvent composition when dissolved in binary solvent mixtures. We then use SANS to evaluate the physical and chemical properties of the stabilizing interfacial films in water-in-model oil emulsions. In Part I of this SANS of emulsions investigation, we unravel the thickness and asphaltenic composition of the interfacial films from emulsions made in three solvents of varying aromaticity. We will show that for these three systems, emulsion stability depended on the asphaltenic composition in the films as opposed to the film thickness, which was nearly constant among the three solvents. In the Part II we seek a more thorough definition of the interfacial film composition by using neutron contrast variation to illuminate not just the asphaltenic makeup, but the solvent, water, and, when applicable, additive composition within the films. Finally, through the use of interfacial shear and dilatational rheology, we explore the various interactions at model oil/water interfaces that influence interfacial film assembly. We find that electrostatic interactions between charged adsorbed species largely dictate the transient evolution of the interfacial elasticity at acidic, neutral, and basic pH. Furthermore, through our comparisons of the interfacial rheological behavior of asphaltenes and model polycyclic compounds, we are able to better understand the physicochemical phenomena that contribute to asphaltene interfacial dynamics. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject interfacial tensiometry en_US
dc.subject interfacial rheology en_US
dc.subject neutron scattering en_US
dc.subject asphaltenes en_US
dc.subject emulsions en_US
dc.title Asphaltene Self-Assembly en_US PhD en_US dissertation en_US Chemical Engineering en_US

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