Aggregate-associated interfacial organization of sodium oleate near zircon surfaces

Introduction Sodium oleate (NaOL) is widely used as an anionic collector for zircon flotation, yet its heterogeneous organization at zircon surfaces remains insufficiently characterized. Methods In this study, Tyndall-scattering observation, dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM), and classical molecular dynamics (MD) simulations were combined to examine NaOL organization on zircon surfaces. Results Tyndall-scattering and DLS measurements established that colloidal NaOL assemblies were present in solution before zircon contact. TEM and STEM-EDS revealed amorphous, carbon-containing domains adjacent to zircon particles after NaOL treatment and washing, while AFM showed an increase of approximately 52 nm in the surface height range after NaOL treatment and water rinsing. These observations indicate that NaOL-treated zircon surfaces contain heterogeneous structures with apparent height variations exceeding the thickness of a molecular monolayer. Under the modeled initial condition and simulation timescale, an unrestrained, preassembled NaOL aggregate moved closer to the zircon surface and retained a water-separated near-surface configuration. Interfacial water remained between the carboxylate groups and surface Zr sites, and no direct Zr-carboxylate coordination was observed during the final 1 ns. Discussion These results provide a multiscale description of heterogeneous NaOL organization at the zircon-water interface and advance the understanding of collector accumulation relevant to fine-zircon flotation.