Review on the Effects of Aging of Microplastics on Its Adsorption Behavior and Photosensitive Behavior in the Environment

Microplastics can come from a wide range of sources. The physical and chemical properties of microplastics change significantly after aging and exhibit distinct behavior characteristics from that of the original microplastics, which causes potential risks to ecology. This study summarizes sources and characteristics of aged microplastics, and reviews the research progress on the effect of aging of microplastics on its adsorption and photosensitive behaviors. The change of surface morphology, functional groups and crystallinity of microplastics after aging can affect specific surface area, internal arrangement of polymer chain, wettability, surface charge and electrostatic interaction with pollutants. Furthermore, the change has influenced on the behavior of microplastics on the adsorption of organic compounds and metal ions in the environment. In addition, the environmental persistent free radicals and reactive oxygen species generated by the photoaging of microplastics not only affect self-oxidation process of microplastics, but also impact the photosensitive behavior of organic compounds. Finally, focusing on research gaps of previous researches, the future research focus and direction are prospected, so as to provide references and suggestions for the future researches on aged microplastics.