Bioinspired Flavylium Surfactants for Hydrophobic Agglomeration of Fine Kaolinite Particles

With increasing environmental concerns and the drawbacks associated with the synthetic materials currently used in industry, there is a growing demand for more eco-friendly and efficient alternatives in mineral processing applications. To help address this, three bioinspired surfactants (M8Flav, M12Flav, and D8Flav) were synthesized by modifying the core structure of flavylium, a plant-based pigment, by installing secondary and tertiary alkyl amines. Hydrophobic agglomeration of fine kaolinite (D_4,3: 10 μm) particles facilitated through the application of these bioinspired surfactants was examined. Spectroscopic, microscopic, and XRD (X-ray diffraction) analyses were performed to interrogate the association of flavylium with kaolinite including the elucidation of potential interactions and mechanisms for the changes in macroscopic properties of the kaolinite aggregates. The surface hydrophobicity of kaolinite was evaluated using the Washburn capillary rise method, with enhanced hydrophobicity observed after treatment with the surfactants. Real-time in situ aggregate size measurements under a controlled shear rate were conducted using an image-derived particle size measuring technique to systematically evaluate the impact of surfactant dosage and alkyl chain configuration on aggregate size and stability. Turbidity reduction of the supernatants and gravitational sedimentation under quiescent conditions of surfactant-treated kaolinite slurries were also examined. These findings reveal the applicability of flavylium-based surfactants, positioning them as valuable tools for improving techniques in clay separation and dewatering processes.