A circular "capture-and-upcycle" strategy for micro/nano-plastic remediation: From aquatic pollutants to fire-safe composites.

The widespread contamination of micro/nano-plastics (MNPs) has become a major environmental concern, highlighting the need for efficient treatment technologies and sustainable disposal methods. Herein, a hydrophobized magnetic lignocellulosic fiber (HLF) adsorbent derived from wood waste was engineered to realize a circular "capture-and-upcycle" strategy. HLF with excellent adsorption capacity can be prepared by modifying lignocellulosic fibers from wood waste through in situ synthesis of nanoscale Fe3O4 particles and silanization. It has achieved equilibrium adsorption capacities of 2544.7 mg g-1 for micro-sized PS and 2571.1 mg g-1 for PMMA. The adsorption mechanism is a synergistic physicochemical interaction dominated by van der Waals forces and hydrophobic effects. Notably, the challenge of adsorbent disposal is addressed by directly transforming the MNPs-saturated HLF into robust functional composites via hot-pressing. The resulting HLF/MNPs composites exhibit ideal mechanical properties with a flexural strength of 151.1 MPa and a tensile strength of 37.6 MPa, far surpassing commercial wood-plastic composites. Furthermore, it exhibits self-extinguishing behavior and improves fire safety due to the action of magnetic particles, and their peak smoke release rate was reduced by 79.3% compared to non-magnetic LF/MNPs composites. This work establishes a scalable, circular approach for remediating aquatic plastic pollution while simultaneously valorizing waste into high-performance engineering materials.