Inter-/intra-molecular synergism improve self-assembly behavior of hydroxamate-modified amino acid surfactant for flocculation of micro-fine particles

Flotation recovery of micro-fine minerals has been constrained by low flotation efficiency due to the large surface area and small quality of fines, causing a huge waste of valuable resources. Herein, we developed a novel hydroxamate-modified N-acyl amino acid surfactant, 2-decanoylamino-4-hydroxycarbamoyl-butyric acid (DHBA), which can self-assemble via synergism among amide, carboxyl, and hydroxamate functional groups for achieving the efficient flocculation and recovery of fine rhodochrosite. The theoretical calculations and interface analyses revealed from microscopic perspective that the intramolecular synergistic chelation effect between carboxyl and hydroxamate groups conferred strong adsorption affinity of DHBA on rhodochrosite. On the other hand, the intermolecular H-bonds not only promote the tight arrangement of collectors on particle surface to enhance hydrophobic association effect, but also induce the agglomeration of collectors into net-like "macromolecules" clusters to produce adsorption bridging for fines. Eventually, the flocculation and flotation tests confirmed that DHBA exhibits a superior flocculation and collecting performance for fine rhodochrosite than very common collector octanoylhydroxamate acid (OHA) (the recovery reached 95.2% for 1 × 10−4 mol·L−1 DHBA while 66.8% for OHA). This research provides a feasible surfactant development strategy for flocculation-flotation.