Abstract
In this study, a new approach, “dynamic wettability”, and atomic force microscopy (AFM) imaging analysis techniques were successfully used to characterize the hydrophobization mechanism of the collector dodecylamine (DDA) on muscovite and talc surfaces. The attachment of bubbles to the minerals was studied through the dynamic contact angle to gain a detailed understanding of the hydrophobization mechanism of DDA on a muscovite and talc surface. AFM imaging and interaction forces were performed to explain the DDA adsorption mechanism on both minerals. Finally, flotation tests were performed to verify the effectiveness of these techniques. After treatments with DDA, the contact angles became much larger compared to initial angles, particularly for muscovite, and the attachment of bubbles on the talc surface was much easier than muscovite due to its natural hydrophobicity. From AFM imaging, both the muscovite and talc showed a similar tendency; the higher the DDA concentration, the more the adsorbed amount. However, the adsorbed amount of DDA on talc surface was obviously more than that on muscovite. As far as interaction forces are concerned, the maximum attractions occurred at certain different concentrations respectively for muscovite and talc and agreed well with the AFM-imaging results. Moreover, results obtained from flotation tests were promising and quite in agreement with the phenomenon of these techniques.
Highlights
Phyllosilicates, after quartz, are most versatile mineral material mined from Earth’s crust for daily and industrial needs
Talc and muscovite (with the composition Mg3 (Si2 O5 )2 (OH)2 and KAl2 (AlSi3 O10 )(OH)2 ), typical hydrophobic and hydrophilic phyllosilicates, both have a 2:1 structure, where one octahedral layer is sandwiched between two tetrahedral layers
The attachment of bubbles to the minerals was studied through the dynamic contact angle to gain a detailed understanding of the hydrophobization mechanism of DDA on the muscovite and talc surface
Summary
Phyllosilicates, after quartz, are most versatile mineral material mined from Earth’s crust for daily and industrial needs. In the structure of muscovite, the tetrahedral layer is usually negatively charged as a result of the ionic isomorphic substitution of about one-fourth of Si4+ by Al3+. These permanent negative charges are neutralized by the interlayer K+ , serving as a bridge between two sheets [4]. In talc structure, this substitution can occur where Si4+ and Mg2+ are replaced by Al3+ and Ca2+ severally [5,6]
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