Synthesis of metal-doped nanoplastics and their utility to investigate fate and behavior in complex environmental systems

Research on the distribution and effects of particulate plastic has intensified in recent years yet, due to analytical challenges, understanding of nanoplastic occurrence and behavior has remained comparatively elusive. However, process studies could greatly aid in defining key parameters for nanoplastic interactions within and transfers between technical and environmental compartments. Here, we provide a method to synthesize nanoplastic particles doped with a chemically entrapped metal used as a tracer, which provides a robust way to more easily, accurately and quantitatively detect nanoplastic in complex media. We show the utility of this approach in batch studies simulating the activated sludge process of a municipal wastewater treatment plant to better understand the fate of nanoplastics in urban environments. We found that the majority of particles were associated with the sludge (>98%), with an average recovery of over 93% of the spiked material achieved. We believe that this approach can be developed further to study the fate, transport, mechanistic behavior and biological uptake of nanoplastics in a variety of systems on different scales.