Efficient dye-containing wastewater treatment: a more effective flocculant structure and flocculation mechanism

Dye-containing wastewater (DCW) poses significant treatment challenges due to the high solubility of organic dyes and the limitations of conventional flocculants, including high dosage requirements and residual chemical pollution. This study introduces an octopus-like biomass-based flocculant (OBF) with a molecularly designed, multi-branched polymer architecture for ultra-efficient remediation of DCW. The innovative design of OBF, featuring cationic “tentacles” and a lignin-based “head,” enables synergistic interactions that achieve >99 % removal of reactive, acidic, and direct dyes at 60–80 % lower dosages than conventional coagulants (e.g., PAC, FeCl₃). In real DCW, OBF consistently outperforms conventional coagulants, meeting stringent water quality standards in a single step. Costing only 0.90 USD per ton, OBF offers a sustainable and cost-effective solution. The synergistic interaction between cationic “tentacles” and lignin-based “head” enhances its affinity for soluble dyes, while weak interaction forces from the lignin core promote efficient mass transfer. This dual mechanism significantly improves dye separation and sludge dewatering, reducing sludge water content. This work presents a sustainable, scalable, and high-performance approach to DCW treatment, advancing chemical engineering through innovative molecular design.