Some Parameters Affecting the Flotation of Cationic Surfactants

Abstract A study was made of the flotation of very dilute solutions of two cationic collectors, hexadecyltrimethylammonium chloride (HTMAC) and dodecyl-pyridinium chloride (DPC), in the presence of added electrolytes. The concentration, charge, and nature of these electrolytes were found to have a pronounced effect on the rates of flotation. The determinations were made at two different gas flow-rates; unexpectedly, the ratios of the flotation rates were found to be different to the total surface areas of the bubbles passing. The discrepancy can be explained on the basis of the repulsions which exist between bubbles due to the charged surfactant species which are adsorbed on them. Small bubbles, which lack kinetic energy, are unable to penetrate the lower reaches of the foam and are swept back into the solution. The latter, therefore, contains too high a proportion of small bubbles which leads to an erroneous estimate of the total surface area available, and casts doubt on the validity of a photographic m...