Controlling the dispersion or flocculation of colloidal suspensions through zeta potential

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00:00:00 Welcome
00:00:13 Introduction
00:00:49 Zeta Potential - Controlling the dispersion or flocculation of colloidal suspensionsAna Morfesis, Ph.D.
00:01:09 Objectives
00:02:59 What is Zeta Potential?
00:04:31 Zeta Potential
00:07:04 Measurement
00:07:07 Electrophoretic Light Scattering
00:08:37 Zeta Potential
00:09:14 Henry’s Function F(ka)
00:10:35 Electrophoretic Light Scattering(Zeta Potential)
00:11:44 Optical Configuration
00:12:36 Example Measurement Cells Capillary & Dip Cells
00:14:07 Electrostatic Stability
00:14:10 Electrostatics
00:15:24 DLVO Theory, 1940’s
00:18:02 Stabilization
00:18:41 ELECTROSTATICS:Origins of Surface Charge in Aqueous Media
00:18:57 Untitled
00:22:36 Polymer Adsorption
00:26:00 Predicting Dispersion Stability
00:26:26 Zeta Potential and pH
00:27:09 Effect of pH on Particle Charge
00:27:44 Zeta Potential and Conductivity
00:28:32 Non Specific Ion Adsorption
00:29:34 Specific Ion Adsorption
00:30:19 Product Performance
00:31:16 Emulsion Preparation
00:32:02 Determination of Steric Layer Thickness
00:33:31 Effect of CaCl2 on Zeta Potential of Emulsions
00:35:36 Effect of CaCl2 on Zeta Potential of Emulsions
00:36:36 Products / Processes that require instability
00:37:46 Bridging Flocculation
00:38:48 Depletion Flocculation
00:40:33 Samples
00:41:00 Laser Diffraction Size Results
00:41:53 Zeta Potential Results for Samples #1 and #2
00:43:52 Conclusion
00:45:55 References
00:46:10 Thank you for your attentionAny questions?
00:52:44 Contact Information
Many large scale industrial processes (paper production, water treatment and dewatering processes) require de-stabilization or flocculation of dispersed particulates. For other industries and products such as foods, cosmetics, paints and pharmaceuticals, the goal often to promote stabilization and enhance shelf life and consumer appeal.

There are a number of factors that influence stability in emulsions, dispersions and suspensions. For example, adsorption of ions or surface active molecules can help to promote charge stabilization through electrostatic repulsion under some conditions, but can neutralize surface charge and destabilize dispersions under different conditions. Also, depending on whether additives adsorb to the surface of the dispersed material or remain in solution they can either promote stability or instability respectively.

Understanding a product’s requirements will determine the objectives with regards to stability, which may be to clarify a solution in order to improve filterability or promote sedimentation or alternatively to prevent an emulsion from phase separating. For ionic dispersions a key factor governing stability/instability is the zeta potential which controls the degree or electrostatic repulsion between neighboring particles.

This webinar will provide an overview of zeta potential and the mechanisms governing stability and instability. Approaches for promoting long term stability and also for inducing rapid flocculation where required will be discussed using real application examples.