A sustainable biomass filler strategy based on bamboo fiber and biochar for achieving multifunctional and recyclable PLA biocomposites.

The development of bio-based composites that simultaneously integrate multifunctionality, robust mechanical performance, and environmental sustainability remains a critical challenge in sustainable materials science. In this work, we propose a rationally designed "hybrid biomass filler" strategy, with varying bamboo fiber/bamboo charcoal ratios, to fabricate a multifunctional polylactic acid (PLA) composite. Unlike conventional composites that rely on acid, alkali, and toxic reagent treatments for modification, this bamboo-based composite employs thermal modification to roughen the fiber surface, which, together with their derivative (bamboo charcoal), synergistically imparts multifunction to PLA. The mechanical interlocking generated by the roughened surface enabled the composite to achieve a flexural strength of 74.06 MPa. Furthermore, leveraging the intrinsic properties of bamboo charcoal (BC), the composite exhibited effective UV shielding (transmittance below 15% at 360 nm), favorable thermal stability, antibacterial activity (>56%), antifungal performance (over 28 days), as well as environmental friendliness and soil degradability. Notably, the composite also demonstrates recyclability, and at the end-of-life stage it exhibits a notable adsorption capacity toward industrial dyes, as further elucidated by molecular dynamics simulations, which reveal the underlying mechanism of its excellent dye uptake. This adsorption capability facilitates convenient recovery and reuse. The entire fabrication process of the PLA composite is free of any chemical reagents, thereby balancing environmental sustainability with economic viability. The sustainable bio-based PLA composite developed in this work transcends the conventional paradigm of single-property optimization, positioning it as a promising candidate for engineering applications. Meanwhile, it offers valuable insights into the comprehensive utilization of engineering waste, demonstrating broad application prospects.