Effects and evolution mechanism of UV-AOPs induced aging of microplastics: fragmentation and organic matter release

Microplastics (MPs) are a widespread emerging pollutant that can harm human health through the food chain or direct ingestion. Therefore, it is of great significance to study the transformation of MPs in water. The mechanism of changes of 3 kinds of MPs under different environmental conditions was studied by Ultraviolet-Advanced oxidation combined process (UV-AOPs). PARAFAC, SEM, FTIR, TOC and LPSA were used to explore the change mechanism. The results showed that the 3 MPs exhibited different degrees of fragmentation and folding with reaction time, temperature and pH. When the reaction time T  = 60 min, pH = 4, t  = 30 °C, V = 15 V, the aging is the most obvious, and the functional groups such as -CH 2 , C O and -CH all change. In addition, the particle sizes of the three kinds of MPs after the reaction were all reduced by an average of 18 % compared with the initial ones. At the same time, a certain amount of DOM is also released, and the main components are aromatic proteins. This study revealed the aging effects of different types of MPs in UV-AOPs process, explored the surface morphological changes of MPs and the release of organic matter, in order to provide more reference and support data for the environmental behavior of MPs.