Exploring the perspective of nano-TiO₂ in hydrophobic modified cationic flocculant preparation: Reaction kinetics and emulsified oil removal performance

To reduce the polymerization difficulty of hydrophobic modified copolymers, a hydrophobic modified cationic flocculant was fabricated using nano-TiO₂ as initiator with acrylamide (AM) and methyl acryloxyethyl dimethyl benzyl ammonium chloride (DML) as monomers, and named it PAD. The copolymers were characterized by scanning electron microscopy (SEM), nuclear magnetic resonance (¹H NMR), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TG). Results verified that PAD was synthesized successfully and nano-TiO₂ was more conducive to DML grafting than traditional photo-initiators. Reaction kinetics demonstrated that the polymerization process was a typical precipitation polymerization initiated by free radicals. Flocculation performance of flocculant on simulated emulsified oil was evaluated and optimized. The simulation results indicated that the flocculation performance of PAD was superior to traditional flocculant, which was attributed to the higher content of DML in PAD. The maximum removal rate of emulsified oil could reach 92.10%, and the corresponding turbidity removal rate was 93.54%. Further, the mechanism studies suggested that the removal of emulsified oil was realized by the synergistic effects of electric neutralization, demulsification, hydrophobic association and adsorption bridging. The findings of this study showed that nano-TiO₂ exhibited a promising prospect in the field of polymer-initiated polymerization.