Octopus-like biomass-based flocculant for broad-spectrum water purification

Flocculation plays a critical role in water purification, directly influencing treatment efficiency and costs. Conventional flocculants primarily target colloids and particulates but exhibit limited efficacy against dissolved organic compounds and emerging contaminants, leading to increased downstream treatment costs. Here, we present an innovative octopus-like biomass-based flocculant (OBF) designed for efficient, one-step removal of a broad-spectrum of water contaminants. The structure of OBF harnesses lignin's interfacial interactions (hydrogen bonding, hydrophobic interactions, and π-π interactions) combined with the electrostatic attraction of cationic branches, achieving removal efficiencies exceeding 90% for humic acid, kaolin, microplastics, and bacteria (96.1% Escherichia coli, 100% Staphylococcus aureus), alongside 98.8% microalgae harvesting. In practical applications, OBF reduced lake water turbidity to 0.75 NTU and municipal wastewater chemical oxygen demand (COD) by 85.2%, surpassing the performance of conventional flocculants. With low toxicity, broad pH adaptability, and sustainable biomass sourcing, OBF offers a scalable, cost-effective solution for water treatment. The structural design and interfacial modulation of this graft polymer represent a significant advance in multifunctional water purification technologies.