Conjugated biopolymer assisted separation of nanoplastics from aqueous systems: a step towards sustainability

Nanoplastics pose a significant environmental concern as they enter aquatic systems through various anthropogenic pathways. Consequently, the removal of nanoplastics from water, particularly polystyrene, is of paramount importance. This work focuses on the separation of polystyrene nanoplastics from aqueous systems, utilising polydopamine (PDA), a conjugated biopolymer, to induce flocculation. The synthesised conjugated biopolymer demonstrated a significant removal efficiency of approximately 75% for polystyrene nanoplastics within 24 hours. This was achieved by adding PDA to simulated water containing polystyrene nanoparticles (20 mg L^-1) and adjusting the pH value to 2, with a PDA dosage of approximately 1 mg per 8 mL of water. The successful flocculation of polystyrene nanoplastics was confirmed through SEM and FTIR analysis. Quantification of polystyrene removal was accomplished using UV-vis spectroscopy. Additionally, regeneration studies of PDA from the formed flocs were conducted to maintain the sustainability of the removal process. Overall, this study highlights the efficacy of using the conjugated biopolymer PDA in the flocculation-based removal of polystyrene nanoplastics. The findings underscore the importance of exploring more sustainable biopolymers for the efficient removal of nanoplastics from aqueous environments.