Journal
LANGMUIR
Volume 26, Issue 1, Pages 63-73Publisher
AMER CHEMICAL SOC
DOI: 10.1021/la9021118
Keywords
-
Ask authors/readers for more resources
The drainage under gravity of a vertical foam film formed oil a wire frame has been investigated. Dual-wavelength optical interferometry was used so that unambiguous fringe order assignments could be made, enabling absolute film thicknesses to be calculated with confidence. Films were stabilized by nonionic polypropylene glycol surfactant. Half-micrometer silica particles with varying degrees of hydrophobicity were added to the film-forming liquid to investigate their effect oil film drainage rate and stability. Hydrophilic particles had little or no effect, while hydrophobic particles slowed the drainage of the film and caused a minor increase in film lifetime, from similar to 10 to similar to 30 s. In both the hydrophilic and hydrophobic cases the films ruptured when they reached a thickness or similar to 2 particle diameters. Particles of intermediate hydrophobicity had the most significant effect, increasing film lifetime by all order of magnitude over that for hydrophilic particles. The intermediate particles allowed films to thin down to a thickness less than the particle diameter, indicating that particles bridge across the entire film. This did not occur with more hydrophobic particles even though they were embedded ill each of the two film surfaces. These results correlate well with previous literature on particle-laden foams. The film thickness and drainage measurements allow drainage mechanisms for the different particles to be identified, thus providing I mechanistic explanation for the observation by several previous authors that foams formed in the presence of particles, for example during mineral processing, have the greatest stability when the particles are of intermediate hydrophobicity.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available