A thermodynamic approach to ion flotation. I. Kinetics of cupric ion flotation with alkylsulfates

A thermodynamic approach was taken to model the removal of cupric ion from sodium dodecylsulfa te(SDS) - Cu, sodium tetradecylsulfate (STS)-Cu and sod ium hexadecylsulfate (SHS)-Cu ion flotation systems. The surface tensions o f these solutions were found to vary linearly with the alkylsulfate concent ration. From these linear equations, it was determined that in copper-alkyl sulfate systems the Gibbs free energy of adsorption changes by - 2.16 kJ mo l (-1) for each additional CII, group on the alkyl chain. Estimated mass tr ansfer coefficients indicated that adsorption should approach or reach equi librium in the batch ion flotation tests reported here. The Gibbs adsorptio n equation was then used to estimate the adsorption densities of copper as a function of time, from the surface tension data. The cupric ion removal k inetics predicted from the surface tension data were consistent with the ex perimentally measured kinetics, provided a term for backflux of colligend w as included, and the bubble size was allowed to increase with increasing su rface tension. (C) 2001 Elsevier Science B.V. All rights reserved.