Leong, Y.K., and Ong, B.C. (2002) Critical zeta potential parameter for the characterization of the flocculated-dispersed state transition in colloidal dispersions. In: Proceedings of the 9th Asia Pacific Confederation of Chemical Engineering (APCChE) Congress and CHEMECA 2002. From: Green Processing and Sustainability: creating opportunities for the chemical and processing industries in the Asian Pacific region, 29 September to 3 October 2002, Christchurch, New Zealand.

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Abstract

A colloidal dispersion in water is flocculated when the net interaction between particles is attractive. This occurs when the van der Waals force is stronger than the electrostatic repulsive force. The van der Waals force is constant at a given separation distance between particles and is strongest at the equilibrium separation distance in the flocculated state. The electrostatic force however may be varied from zero to a high value by surface potential control. pH is often used to manipulate the surface potential. The easily measurable zeta potential is normally used in place of the surface potential. This potential is measured at a shear plane near the particle surface and is proportional to the surface potential at constant ionic strength. There is a critical zeta potential where the electrostatic force is equal to the van der Waals force and the dispersion becomes dispersed. At fixed ionic strength the critical zeta potential is indirectly a measure of the strength of the van der Waals force in the flocculated state. Thus it is also a measure of the Hamaker constant, an important material property and parameter in the van der Waals equation. The critical zeta potential at fixed ionic strength of various oxide dispersions were compared. The yield stress and zeta potential data were used to determine the critical zeta potential at flocculated-dispersed state transition.

Item ID:	14630
Item Type:	Conference Item (Research - E1)
ISBN:	978-0-473-09252-8
Keywords:	critical zeta potential; hamaker constant; oxides; yield stress
Date Deposited:	07 Mar 2018 23:29
FoR Codes:	09 ENGINEERING > 0912 Materials Engineering > 091201 Ceramics @ 100%
SEO Codes:	86 MANUFACTURING > 8610 Ceramics, Glass and Industrial Mineral Products > 861099 Ceramics, Glass and Industrial Mineral Products not elsewhere classified @ 100%
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