Polydopamine-coated bacterial cellulose spheroids for enhanced micro/nanoplastics removal and closed-loop upcycling

The pervasive contamination of micro/nanoplastics (MNPs) has emerged as a growing threat to global ecosystems and human health. In this study, a sustainable remediation strategy was proposed using polydopamine (PDA)-modified bacterial cellulose (BC) nanofibrous spheroids (PDA-BC) for the efficient sequestration of MNPs from aqueous environments. The PDA-BC spheroids demonstrated robust capture performance over a wide particle-size range, as well as across varying temperatures, pH values, and salinities, achieving an adsorption capacity of 461.62 ± 61.43 mg/g for 100 nm polyethylene terephthalate (PET) MNPs. Effective removal was also demonstrated for multiple polymer types, including polystyrene (PS), polypropylene (PP), and polyethylene (PE), with maintained its efficacy in real-world water matrices. Mechanistic analyses revealed that the superior performance was attributed to the synergistic contributions of physical interception and interfacial interactions, including electrostatic interactions, hydrogen bonding, and van der Waals forces. Beyond remediation, the discarded MNPs-loaded PDA-BC adsorbents were upcycled into mechanically reinforced composite films via citric acid-mediated hot-pressing, resulting in a 42.06% increase in tensile strength. This work not only enabled effective MNPs sequestration but also transformed waste into value-added products, offering a closed-loop route solution for MNPs pollution mitigation.