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Permanent link (DOI): https://doi.org/10.7939/R34J0B78R
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Study of Anisotropic Surface Property of Phyllosilicates by Atomic Force Microscopy Open Access
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- Type of item
- Degree grantor
University of Alberta
- Author or creator
- Supervisor and department
Xu, zhenghe (Chemical and Materials Engineering)
Masliyah, Jacob (Chemical and Materials Engineering)
- Examining committee member and department
Pawlik,Marek (Mining Engineering)
Zeng, Hongbo (Chemical and Materials Engineering)
Tang, Tian (Mechanical Engineering)
Department of Chemical and Materials Engineering
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
The phyllosilicates are an important class of valuable industrial minerals and play an essential role in many disciplines. The surface properties of phyllosilicate minerals are a topic of crucial importance as they directly affect all industrial aspects in mineral processing. The objective of this research is to investigate the anisotropic surface properties of selected phyllosilicate minerals, focuing on surface charging properties of their basal planes and edge surfaces, and their related particle interactions and rheological properties of particle suspensions.
An ultramicrotome cutting technique was developed to prepare molecularly smooth edge surfaces of phyllosilicates, which allows direct measurement of interaction forces between AFM tips and the prepared surfaces in various electrolyte solutions. A theoretical model based on the geometry of AFM tip was used to fit the measured force profiles to the classical DLVO theory at different boundary conditions, which allows direct determination of Stern potentials of different phyllosilicate surfaces.
The surface charging behavior of muscovite and talc basal planes and edge surfaces was determined as a function of pH. The basal planes of both muscovite and talc were found to carry a pH-independent permanent negative charge, while the charges on their edge surfaces were highly pH-dependent. The effect of the concentration of two divalent cations: Mg2+ and Ca2+ on the Stern potential of different surfaces of phyllosilicate minerals was investigated. The interaction energies of various associations between talc surfaces, such as basal plane-basal plane, edge-edge and basal plane-edge were calculated using the Stern potential values of talc basal planes and edge surfaces obtained from fitting the measured force profiles to the classical DLVO theory. The attractive interaction between talc basal planes and edge surfaces was found to dominate the rheological behavior of talc suspensions.
The findings from this dissertation are anticipated to provide a basis for understanding the colloidal behavior of phyllosilicates in mineral processing and hence better control their process performance.
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