| The conventional methods used to remove toxic metal ions, such as solvent extraction, ion exchange, and chemical precipitation have shortcomings for treating large volumes of dilute solutions.;A flotation column was used to study ion and precipitate flotation. The removal of Cu and Cr(III) was studied using sodium dodecylsulfate (SDS); Cd was studied using SDS and dodecylammonium chloride: Pb was studied using SDS, sodium dodecylsulfonate, and sodium dodecanoate; and anionic Cr(VI) was studied using hexylamine, dodecylamine, and dodecylammonium chloride. The metal ion concentration studied was 0.3 mmol dm;Using SDS at a stoichiometric ratio of 1.1, the concentrations of Cu, Cd, Pb, and Cr(III) in solution were reduced from 0.3 to ;Cu dodecylsulfate and Cd dodecylsulfate were removed by ion flotation, whereas Pb dodecylsulfate, Pb dodecylsulfonate, Pb dodecanoate, and Cr(III) dodecylsulfate were removed by both ion and precipitate flotation. The kinetics of metal removal were faster in precipitate flotation than for ion flotation. Less foam formed in precipitate flotation than in ion flotation.;The removal of dodecylsulfate was low when the only counter ion was Na and higher when the counter ions were (Pb + Na) or (Cr(III) + Na). At a dodecylsulfate concentration of ;The economics for ion and precipitate flotation would be more favorable if the collector could be recovered and recycled from the foam product. Metal recovery by precipitation of sulfides or electrolysis appears to be very promising, allowing dodecylsulfate to be recycled from the foam produced in ion flotation. (Abstract shortened by UMI.). |
