As single-use plastics continue to be produced at an increasing rate, the threat of micro- and nano-sized plastic pollution exists in the environment. Weathering processes, such as photodegradation, allow petroleum-derived polymers to become oxidized, and potentially enter the environment with harmful consequences for living species. The scope of this study centers on the photo-oxidation of micro- and nano-sized polystyrene and other materials by analyzing the role of reactive oxygen species (ROS), such as hydroxyl radical and singlet oxygen, in photodegradation mechanisms. Chemical probes, such as benzoic acid and furfuryl alcohol, were employed to determine the rate and steady state concentrations of ROS produced from irradiated micro- and nanoplastics under varying conditions.  Suspensions of plastic particles and a chemical probe were prepared in pure water, then placed under simulated sunlight. In addition to changes to time and probe concentration, plastic loading was altered to compare degradation behavior to particle loadings. HPLC allowed detection of ROS formation through determination of characteristic reaction products. This study revealed formation of hydroxyl radical from solar irradiated polystyrene, indicating that micro- and nanoplastics contribute to the oxidative capacity of sunlit waters.  Results provide insight into the role of micro- and nanoplastics on ROS formation in aquatic systems and their impacts on fate and transport of plastics and other dissolved or suspended materials.

Solar photoproduction of reactive oxygen species from micro- and nanoplastics in aqueous media

ACS Spring 2022

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