Adsorption of levofloxacin by ultraviolet aging microplastics

Microplastics can combine with pollutants such as antibiotics and pose a threat to the environment and organisms. At the same time, the inevitable aging behavior of microplastics in the actual environment leads to changes in their physical and chemical properties, and thus changes the reaction mechanism between microplastics and other pollutants. In this study, we used three common microplastics PE/PS/PA to study the adsorption behavior of levofloxacin hydrochloride. Ultraviolet aging method was used to simulate the aging process of levofloxacin hydrochloride under sunlight, and compared with that of before aging. The results showed that the order of adsorption capacity was PS-UV > PA-UV > PE-UV > PA > PS > PE. Aging behavior can significantly enhance the adsorption capacity of microplastics to pollutants. Both Langmuir and Freundlich models can be used to fit the isothermal adsorption process well, indicating that the adsorption process was not a simple monolayer adsorption, but also a multi-molecular layer adsorption. The experiments showed that the adsorption process was affected by various mechanisms, including π-π conjugation, hydrogen bond, ion exchange and electrostatic interaction. This study elucidated the interaction mechanism between microplastics and levofloxacin hydrochloride, which has important significance for future control of microplastics and antibiotic pollution. © 2023 Elsevier Ltd