Investigation of the Adsorption of Norfloxacin by Biodegradable and Non-biodegradable Microplastics Aged by Chemical Oxidation

The combined pollution of microplastics (MPs) and antibiotics in the water environment has received much attention in the past decade. MPs are often considered ideal adsorption carriers for organic matter (OM) in the water environment. Meanwhile, mechanical wear and ultraviolet radiation will make MPs age and enhance the adsorption of OM on MPs. In this study, biodegradable polylactic acid (PLA), non-biodegradable polyethylene terephthalate (PET), and polypropylene (PP) were aged by K 2 S 2 O 8 advanced oxidation. The adsorption behavior of MPs before and after aging to norfloxacin antibiotic (NOR) was studied. Results showed that the surface of MPs after aging had cracked and become rougher. The aged PLA was the most changed among the three kinds of aged MPs, and its specific surface area, equilibrium, and saturated adsorption capacity of aged PLA reached 15.826 m 2 /g, 1.184 mg/g, and 15.241 mg/g, respectively. Most of the adsorption of NOR on pristine and aged MPs was more aligned with the pseudo-first-order. The NOR was multiple adsorptions on the surface of aged PLA and aged PET, while it was monolayer adsorption on the surface of aged PP. In addition, it was different for the effect of pH, salinity, and dissolved organic matter (DOM) on the adsorption of NOR on different MPs. These results suggested that the chemical aging of MPs can enhance the adsorption capacity of MPs to NOR and promote the carrier effect of it to NOR.