Thioether-bridged surfactants for interfacial hydrophobic regulation and enhanced mineral flotation recovery

Surfactant modification to improve interfacial hydrophobicity is widely employed in separation applications such as mineral recovery. However, few modifications effectively enhance both the inherent hydrophobicity of the surfactant and its surface-anchoring capacity. In this study, we propose a strategy to incorporate a thioether group into a hydroxamate surfactant, resulting in the synthesis of N-hydroxy-2-(octylthio)acetamide (OTHA). Compared to the thioether-free surfactant (OHA), the thioether group significantly improves the metal-anchoring capability of the surfactant, demonstrating a twofold increase in adsorption on hydrophilic cassiterite surfaces. Meanwhile, the inherent hydrophobicity of the thioether group enhances the hydrophobization of the target mineral surface and improves bubble-surface interactions. The robust hydrophobicity-inducing ability of OTHA successfully increases the flotation recovery of hydrophilic cassiterite particles, with a marked improvement from 72.5% to 95.0%. This work presents a paradigm for surfactant modification, enabling tailored hydrophobic interfaces for practical applications such as mineral separation, oil-gas extraction, waterproof materials, and functional coatings.