Adsorption mechanism of sodium oleate at hematite/quartz–water interfaces: A quantitative molecular insight

The interaction of surfactants at minerals-water interfaces in flotation system plays an important role in minerals separation. Although the increasing number of reports have been published on the sodium oleate (NaOL) adsorption at the mineral–water interface, there has been little development in describing and predicting its adsorption behaviors from a quantitative molecular insight. In this study, based the adsorption experiments, the adsorption characteristics of NaOL on the hematite/quartz-water interfaces were quantitatively depicted using the surface complexation model (SCM). There was a monodentate binding form between the function group on NaOL and the hematite and quartz surface sites during SCM fitting. The binding constants (logK) of NaOL are 10.72 (≡Fe-OL) and 8.03 (≡Si-OL), respectively. Notably, there are more positive ≡FeOH₂⁺ site on the hematite surface, and it has strong adsorption capacity with anionic surfactant NaOL. Moreover, the minerals surface potentials, NaOL adsorption capacity and flotation recovery in mixed ore systems were successfully predicted by the model. This study provides a credible evaluation of the adsorption characteristics of NaOL under a broad scope of pH and concentration conditions. Meanwhile, quantitative analysis of surfactants adsorption at minerals-water interfaces is beneficial for the intelligence of mineral processing technology and efficient separation of minerals.