Application of Magnetic Chitosan Composite for Adsorption of Polyethylene Terephthalate (PET) and Polystyrene (PS) Nanoplastics

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A magnetic chitosan composite was applied to study the adsorption of nanoplastics (NPs), prepared from single-use plastic bottles and packaging materials by mechanical fragmentation (MF) and nanoprecipitation (NPR), on magnetic biopolymer. The resulting polystyrene (PS) and polyethylene terephthalate (PET) samples were characterised by SEM, TEM, DLS, zeta potential and ATR-FTIR. The magnetic chitosan composite (MCSC) was prepared by synthesising Fe3O4 nanoparticles and modifying chitosan through crosslinking. Batch experiments were conducted to study the adsorption of PSNPR, PETNPR, and PETMF nanoplastics on the magnetic chitosan composite. Changes during the adsorption process were monitored using UV–Vis spectroscopy. The maximum efficiencies of PSNPR and PETMF are 97% and 94%, respectively, at pH 5, whereas the maximum efficiency of PETNPR is 94% at pH 6. The Langmuir maximum adsorption capacity (qm) values for PSNPR, PETNPR, and PETMF are 26.7, 13.8, and 19.4 mg g−1, respectively. The Freundlich and Langmuir isotherms, thermodynamic studies, as well as pseudo-first-order and pseudo-second-order models, were applied to study the adsorption behaviour of nanoparticles on the magnetic chitosan composite. The XPS and FT-IR data for pristine and adsorbed nanoplastics as well as modelling results indicated complex adsorption mechanisms.