Sorption of Pharmaceuticals on Microplastics

The presence of microplastics (MPs) in the environment has gained increasing attention in recent years. They are emerging environmental contaminants distributed worldwide that may have a negative impact on ecosystems, organisms, and even in human health. However, MPs are not alone in the environment and coexist with many other organic and inorganic contaminants, such as pharmaceuticals. Due to their physical-chemical properties, MPs have the ability to sorb pharmaceuticals from the surrounding water column in their surface, acting as vectors or carriers in the aquatic environment. MPs properties, such as type of polymer, particle size, surface area, polarity, and pharmaceuticals characteristics (e.g., log Kow, pKa), can directly affect their sorption behavior. Moreover, MPs may undergo different aging/weathering processes in the environment, which contribute to their degradation by decreasing MPs size and changing the particle surface topography and chemistry. These processes will induce changes in the physical-chemical properties of MPs, affecting their sorption behavior. In general, it is expected that aged MPs have a higher sorption capacity for pharmaceuticals than pristine ones. This chapter focuses on the existing studies on the sorption of pharmaceuticals on MPs. A review of the current knowledge on the sorption/desorption mechanisms involved in the sorption behavior of pharmaceuticals on MPs and how this is influenced by environmental factors (e.g., aging/weathering processes, pH, salinity, dissolved organic matter) is provided.