Download the full-sized PDF of Probing the Molecular Interactions of Asphaltenes in Organic Solvents Using a Surface Forces ApparatusDownload the full-sized PDF



Permanent link (DOI):


Export to: EndNote  |  Zotero  |  Mendeley


This file is in the following communities:

Graduate Studies and Research, Faculty of


This file is in the following collections:

Theses and Dissertations

Probing the Molecular Interactions of Asphaltenes in Organic Solvents Using a Surface Forces Apparatus Open Access


Other title
Emulsion Stability
Surface Forces Apparatus
Type of item
Degree grantor
University of Alberta
Author or creator
Natarajan, Anand
Supervisor and department
Xu, Zhenghe (Department of Chemical and Materials Engineering)
Zeng, Hongbo (Department of Chemical and Materials Engineering)
Examining committee member and department
Fan, Maohong (School of Energy Resouorces, University of Wyoming)
Xu, Zhenghe (Department of Chemical and Materials Engineering)
Liu, Qingxia (Department of Chemical and Materials Engineering)
Serpe, Michael (Department of Chemistry)
Zeng, Hongbo (Department of Chemical and Materials Engineering)
Masliyah, Jacob (Department of Chemical and Materials Engineering)
Department of Chemical and Materials Engineering
Materials Engineering
Date accepted
Graduation date
Doctor of Philosophy
Degree level
A fundamental understanding of the stability of water-in-bitumen emulsions stabilized by surface active agents requires a good description of the molecular interactions between the different materials in contact. Of these surface active agents, asphaltenes and oil contaminated fine solids are major contributors to a stable emulsion. In this thesis, the molecular interactions of asphaltene surfaces in model oils, toluene and heptane, were measured using a surface forces apparatus. Adsorption of asphaltenes on mica surfaces was studied to understand the interactions that can occur between crude oil components and oil-contaminated fine solids during the extraction process. The repulsive force measured between two asphaltene surfaces in toluene is attributed to steric repulsion, whereas the weak attractive force measured in heptane can be described by van der Waals forces. By fitting the measured force-distance profiles with theoretical models, the presence of secondary structures of asphaltenes in toluene was observed, stemming from the polydispersity/complexity of asphaltene molecules/aggregates. The adsorption results show that asphaltene adsorption onto mica is highly dependent on adsorption time and concentration of the solution. The adsorption process was identified to be controlled by diffusion of asphaltenes from the bulk solution to the mica surface. Ethyl Cellulose (EC) is an effective demulsifier for water-in-bitumen emulsions. The interactions between asphaltenes, mica and EC were measured to understand the molecular mechanisms involved in destabilizing water-in-bitumen emulsions. Both EC and asphaltenes were observed to irreversibly adsorb on mica surface. The repulsive interaction forces measured during approach between EC and asphaltene surfaces in toluene were shown to have a steric nature, while the adhesive force measured between them during separation are attributed to attractive bridging forces between mica surfaces. Asphaltenes were observed to physisorb on EC coated surfaces and contribute to bridging adhesion. On the other hand, EC molecules were observed to gradually displace the irreversibly coated asphaltene films from mica surface, in which the asphaltenes are pushed into globule structures or nanoaggregates. The above results provide an insight into the basic interaction mechanisms of asphaltenes in organic media and hence in crude oil and bitumen production.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Natarajan, A.; Xie, J.; Wang, S.; Liu, Q.; Masliyah, J.; Zeng, H.; Xu, Z. J. Phys. Chem. C 2011, 115, 16043-16051.

File Details

Date Uploaded
Date Modified
Audit Status
Audits have not yet been run on this file.
File format: pdf (Portable Document Format)
Mime type: application/pdf
File size: 4661863
Last modified: 2015:10:12 11:28:49-06:00
Filename: Natarajan_Anand_Spring 2014.pdf
Original checksum: da4304603e716db1e61878b9e2ebe059
Well formed: false
Valid: false
Status message: Unexpected error in findFonts java.lang.ClassCastException: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject cannot be cast to edu.harvard.hul.ois.jhove.module.pdf.PdfDictionary offset=2748
Status message: Invalid Annotation list offset=4610230
File language: en-CA
Activity of users you follow
User Activity Date