A new approach for characterization of hydrophobization mechanisms of surfactants on muscovite surface

Abstract

A new approach ‘dynamic contact angle analysis’ has been used in the present investigation to characterize the hydrophobization mechanisms of single and mixed surfactants on muscovite surface. The hydrophobization of muscovite surface was achieved by anionic NaOL (sodium oleate), cationic DDA (dodecylamine) and combined DDA/NaOL surfactants. Besides dynamic contact angle analysis, AFM and flotation tests were carried out to gain detail information about the wettability of muscovite, adhesion ability of bubbles towards muscovite surface and adsorption of single and mixed DDA/NaOL surfactants on the muscovite surface. From flotation results, the highest recovery (>90%) was obtained by the mixed DDA/NaOL when they were used at a ratio of 1:3 and the concentration of 2 × 10−4 mol/L. The dynamic contact angle tests showed that the angles achieved by DDA/NaOL were bigger and the bubbles were adhered more easily, which are in agreement with the flotation results. AFM imaging indicated that, as compared to single collectors, the combined surfactants adsorbed uniformly on the muscovite surface as bulks and formed a tight adsorption multilayer. The attraction in mixed DDA/NaOL was stronger than that in single DDA with the same jump-in distance at around 15 nm and the long-range repulsion was observed in single NaOL.