1975 Volume 48 Issue 6 Pages 1745-1749
The ion flotation of Cd2+ ions has been investigated from the surface chemical point of view in comparison with the case of Cu2+ ions reported previously. The effects of the change in the pH, the anionic and cationic surfactants, and bentonite on the flotation rate have also been studied. Sodium α-sulfolaurate proved to be one of the best surfactants among the anionic surfactants used for removing Cd2+ ions, showing as high as a 97% removal. About 97% of the Cd2+ ions could be floated in the region of pH 11.3 when a cationic surfactant was used with bentonite, regardless of the exact surfactant used. The addition of bentonite reduced the foam formation and liquid hold-up, resulting in effective bubble flotation. This behavior was as a whole similar to that of Cu2+ ions. However, in all the flotation systems tested, the flotation rate increased sharply at about pH 8, and the flotation rate vs. pH curve for Cd2+ shifted towards a more alkaline region than that for Cu2+, because of the stronger basic nature of the former. Also, the flotation rate of Cd2+ ions for the Cd2+-anionic surfactant systems attained a steady value after about 7 min, longer than the 2-min gas flow required in the case of Cu2+ ion flotation. The adjustment of the pH using ammonia gave a lower rate of flotation than in the case of flotation using sodium hydroxide.
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