Amide group enhanced self-assembly and adsorption of thioether-containing hydroxamic acid on cassiterite surface

Modified surfactants can regulate their adsorption at the target surface and are essential for various separation applications such as froth flotation. Thioether-containing hydroxamic acid (BTHA) is an excellent oxidized-ore collector with poor dispersibility. Herein, acylamino, which possesses the ability to improve the surfactants' self-assembly and dispersion, was introduced to synthesize N-[6-(hydroxyamino)-6-oxohexyl] benzylthioacetamide (BTAHA); thus, applying it to cassiterite flotation. Surface tension, adsorption capacity, in situ AFM, and surface energy results reveal BTAHA displays strong bubble stability and readily adsorbs onto the mineral's surface, promoting hydrophobic flotation. BTAHA is an effective cassiterite collector and has good separation effects on cassiterite against calcite. It can form Van der Waals forces and five-membered hydroxamate-(O,O)-Sn rings with Sn atoms on cassiterite surfaces via thioether and hydroxamate groups. Meanwhile, the presence of intermolecular hydrogen bond between the amide groups facilitates the self-assembly of the collectors on the cassiterite surface, and has broad industrial application prospects in various separation processes.