colloid stability and interactions in non-aqueous media: an evaluation of clay stability in bitumen

1. Colloid Stability and Interactions in Non-aqueous Media:An Evaluation of Clay Stability in Bitumen

2. Overview: Non-aqueous media Polar and nonpolar dispersion media Interaction forces in Non-aqueous media Stability of Colloids in Non-aqueous media Acid-Base Interactions; Influence of water and polymers Measuring and Quantifying Colloidal Forces: AFM Application to Geochemical Engineering: Tar sands Investigation into Clay-Bitumen Stability Treatment to Enhance Bitumen Recovery Implementing Enhanced Refining Conclusion An Understanding of Non-aqueous Colloidal Systems

3. Non-Aqueous Media Polar media is made up of molecules that have separate centers of positive and negative charge, creating a dipole moment. Nonpolar media is made up of molecules that have a more symmetrical distribution of electrons, such that no dipole moment is created.

4. Interfacial Interaction Forces: Electrostatics Aqueous media: electrostatic interactions, generally repulsive, are dictated by electric double-layer interactions

5. Interfacial Interaction Forces: Acid-Base Acid-Base Interactions: Bronsted-Lowry Theory – proton donor (acid) and proton acceptor (base) interfacial reactions ? Good for Aqueous Media SH2+ + B- SH + HB S- + H2B+ where, SH = particle and HB = media Lewis Theory – electron-pair acceptor (acid) and an electron pair-donor (base) ? Valid for Aqueous and Non-aqueous Media S+ + BYA- SA + BY SAY- + B+ where, SA = particle and BY = media Lewis Acid-Base (AB) interactions between colloid surface and dispersion media cause charging of particles ? influence ultimate attraction or repulsion of colloidal system

6. Interfacial Interaction Forces: van der Waals Lifishtz-van der Waals (LW) interactions, unlike electrostatics and acid-base interactions, do not depend on the media, thus same express valid in both Aqueous and Non-Aqueous media 2Two spheres equal Radius; Rs >> d where, A = Hamaker constant; Rs = radius of colloid; d = separation distance Hamaker constant for both Aqueous and Non-aqueous systems dictates van der Waals interactions; dependent on colloid size and square of separation distance

7. Colloid Stability in Non-Aqueous Media DLVO Theory: total interaction energy equated as sum of van der Waals and electrostatic interactions where, and Extended-DLVO (XDLVO) Theory: total interaction energy equated as sum of van der Waals, electrostatic, and acid-base interactions where,

8. Influence of Water in Non-Aqueous Colloidal Systems: Practically Impossible to eliminate all H2O molecules from nonpolar media Tends to adsorb on a colloid surface Influences surface charge Colloid Stability in Non-Aqueous Media

9. Measuring Colloid Forces In Situ: Atomic Force Microscopy (AFM) Directly measure interfacial forces as a function of separation distance between a colloid and a substrate in gaseous or liquid media

10. Colloidal Science of Non-Aqueous System in Geochemical Engineering: Tar Sands Colloids in geological systems = silts and clays Silts and Clays predominately created from weathering processes partially dictated by carbonic acid

11. Refining Tar Sands Water-Based Extraction Process (WBEP): Liberation: hot water is added to tar sand to form slurry, liberating bitumen from sand grains Aeration: bitumen slurry is aerated, creating bitumen-air bubbles, float to surface = bitumen-rich froth

12. Investigation by Liu et al. (2005) Interaction Forces Between Bitumen and Colloids/Clays Influence of pH and Ca2+ in interaction forces Experiments Forces between bitumen and silica colloid in 1mM KCl XDLVO Modeling of various systems Investigating Bitumen-Colloid Interactions: AFM and XDLVO Modeling

13. Findings from Liu et al. (2005) Investigation: Investigating Bitumen-Colloid Interactions: AFM and XDLVO Modeling

14. Repulsive interaction force between bitumen and clays from “good-ore”, but attractive interaction force between bitumen and clays from “poor-ore” - Possibly due to low content of clays in “good-ore” and lower divalent ions, and greater alkalinity, and visa versa for “poor-ores” - Possibly higher Montmorillonite (stronger adhesion to bitumen) content then Kaolinite in “poor-ore” Investigating Bitumen-Colloid Interactions: AFM and XDLVO Modeling

15. Conclusion: Colloid Stability in Non-Aqueous Media to Improve Geochemical Engineering In situ measurements, using AFM, provide useful information to understand colloid interactions and stability in non-aqueous media Increase Bitumen Liberation from Tar Sands Increase pH, reduce divalent ion (Ca2+, Mg2+) concentrations Increase temperature = increased viscosity and reduced density Determine optimal Polymer/Surfactant concentration to destabilize Determine correlation with DLVO or XDLVO model to determine which interaction force is dominating bitumen-clay interaction Continued research in various clay interactions with Bitumen, and how Bitumen liberation can be optimize by controlling processing water and manipulating colloid system chemistry, while minimizing environmental impacts.

16. References: Literature: Lyklema, J. (1968). Principles of the stability of lyophobic colloidal dispersions in non-aqueous media. Advances in Colloid and Interface Science, 2(2), 65-114. Giese, R. F., and van Oss, C. J. (2002). Colloid and Surface Properties of Clays and Related Minerals. New York: Marcel Dekker, Inc. Liu, J., Xu, Z., and Masliyah, J. (2005). Interaction forces in bitumen extraction from oil sands. Journal of Colloid and Interface Science, 287, 507-520. Long, J. H., Li, H., Xu, Z., Masliyah, J. H. (2006a). Role of Colloidal Interactions in Oil Sand Tailings Treatment. American Institutes of Chemical Engineers. Long, J., Xu, Z., and Masliyah, J. H. (2006b). Role of illite-illite interactions in oil sands processing. Colloids and Surfaces A: Physiochemical Engineering Aspects, 281, 202-214. van Oss, C. J. (1994). Interfacial Forces in Aqueous Media. New York: Marcel Dekker, Inc. Graphics: Polar and Nonpolar Illustrations. http://www.school-for-champions.com/chemistry/polar_molecules.htm Electric Double-Layer. http://www.informaworld.com/ampp/image?path=/713172974/758570721/F0001.png Huckel Approximation. http://www.silver-colloids.com/Tutorials/Intro/henrys.jpg Influence of Water and Polymer Illustration. http://www.chm.bris.ac.uk/briscoe-group/nonPolar.html Polymer Stabilization Graphics. Shi, J. (2006). Oxide nanoparticles and nanostructured coatings by wet chemical processing (Dissertation). Ohio State University, Materials Science and Engineering. SEM Image of Colloid on Cantilever. Imaged by Peter Bush at the South Campus Instrumentation Center, Buffalo, NY. AFM Force Curves. Created by Michael Bower, for MS research at SUNY-Buffalo, NY Tar Sand in Hands. http://ostseis.anl.gov/guide/tarsands/index.cfm Map of Tar Sands in Alberta, Canada. http://en.wikipedia.org/wiki/Image:Athabasca_Oil_Sands_map.png Tar Sand Extraction Basin. http://ostseis.anl.gov/guide/tarsands/index.cfm SEM of Illite on cantilever. Long, J., Xu, Z., and Masliyah, J. H. (2006b). Role of illite-illite interactions in oil sands processing. Colloids and Surfaces A: Physiochemical Engineering Aspects, 281, 202-214.

17. Questions?