Mimosa-inspired dual-responsive flocculant with controllable hydrophobicity/hydrophilicity reconstruction for the purification of triclosan containing emulsified wastewater.

The coexistence of triclosan (TCS) in emulsified oil wastewater exacerbates potential environmental and health risks, whereas few studies have reported the simultaneous removal of oil and TCS. Wastewater pH and temperature fluctuations narrowed the operational windows of conventional flocculants. Inspired by the dynamic conformational reconfiguration of mimosa pudica, a novel thermo- and pH-responsive flocculant (CGNS) was synthesized by introducing sodium methacrylate (SMA) and poly(N-isopropylacrylamide) (PNIPAM) in this study. Jar tests demonstrated that the lower critical solution temperature and the critical pH transition of CGNS were 32°C and 7.6, respectively. The removal efficiencies of TCS and oil reached 88.56% and 88.88% under the optimal conditions, respectively, significantly outperforming cationic polyacrylamides. In addition, the excellent flotation and recovery of flocs were observed. Mechanism analysis revealed TCS and SMA chains underwent protonation, while PNIPAM chains contracted and transitioned from hydrophilicity to hydrophobicity under high temperatures and acidity, contributing to enhanced pollutant capture. The adsorption bridging and charge neutralization capabilities of CGNS, together with multiple non-covalent interactions, ensured the flocculation performance under various pH and temperature conditions. This study provided a robust technological and theoretical foundation for the synergistic flocculation of emerging contaminants containing emulsified wastewater.