Rugosities and Stability of Air-Water-Solid Films

Despite these complications, it seems reasonable to suppose that the disjoining forces across aqueous films on hydrophobic solids (or those rendered hydrophobic) 

FIGURE 4.61 Bubble rising through suspension of hydrophobic particles under laminar flow illustrating inefficient interception of particles by bubbles (schematic). 

FIGURE 4.62 Collection efficiencies for rough quartz and spherical glass particles, (a) Quartz particles of 31 microns Stokes equivalent diameter, (b) Spherical glass particles of 32-micron diameter. (From Anfruns, J.F., Kitchener, J.A., Trans. Inst. Min. Metall., London C, 86, 9, 1977, reproduced by permission of the Institute of Mining and Metallurgy, London.) 

FIGURE 4.63 Effect of rugosities on capillary pressure in film formed between particle and air-water surface as it intercepts a bubble in flotation experiment, (a) Smooth spherical particle of radius (b) Spherical particle also of radius but with rugosities of radius where r . 

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