Particle Wettability by Equilibrium Capillary Pressure Measurements

Abstract

Experimental apparatus for the determination of powder wettability is described. The principle of the technique is based on the measurement of the equilibrium capillary pressure in a packed bed of particles. Both the macroscopic solid-solution-vapour contact angle, θ, and the specific surface area, A(m ² g⁻¹), of the powder, can be obtained. Experiments on angular quartz particles have been performed. A wide range of situations have been covered: hydrophilic and hydrophobic particles wetted with water, a variety of organic liquids and solutions of surfactants. The results show that reliable and reproducible values for θ and A for angular and relatively coarse powders can be obtained with the proposed equipment for advancing liquid fronts in the absence of soluble surfactants. In the latter case, and for receding liquid fronts in general, only qualitative trends have been obtained.

Key words:

• particle wettability
• powder
• contact angle
• surface area
• capillary pressure

Additional information

Notes on contributors

DAVID DIGGINS

Sola Optical, Sherriffs Road, Lonsdale, South Australia 5095

JOHN RALSTON

to whom all correspondence should be addressed