Adsorption behavior of levofloxacin hydrochloride on non-degradable microplastics aging with H2O2

Plastics pollutants, especially microplastics (MPs, <5 mm in diameter) and levofloxacin hydrochloride (Lev-HCl) often co-exist in the aquatic environment. To explore the adsorption processes and mechanisms of Lev-HCl by non-degradable MPs, in this study, H2O2 oxidation was used to age polyvinyl chloride (PVC), polystyrene (PS), and polyethylene terephthalate (PET) MPs. The results demonstrated that the equilibrium adsorption capacity increased significantly after aging, as H2O2-PET (1.167 mg/g) > PET (0.995 mg/g), H2O2-PS (1.057 mg/g) > PS (0.957 mg/g), H2O2-PVC (1.107 mg/g) > PVC (0.975 mg/g). After H2O2 aging, the hydrogen bond (-OH) was more obvious, and pi-pi interactions were significantly enhanced. These non-degradable MPs mainly adsorbed Lev-HCl by micropore filling (contributions: PVC 65.9%, PS 56%, PET 63.5%). The current study highlights the potential of non-degradable MPs to act as a vector for Lev-HCl in the aquatic environment, especially after H2O2 aging.