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Generation and Characterization of Environmentally-Representative Nanoplastic Particles
Citation:
Surette, M. AND K. Rogers. Generation and Characterization of Environmentally-Representative Nanoplastic Particles. 2021 SETAC North America Annual Meeting, Virtual, November 14 - 18, 2021.
Impact/Purpose:
While the pervasiveness of plastic pollution in the environment is well-established, little is known regarding the extent, distribution, and effects of the smallest size fraction, referred to as nanoplastics (generally considered to be plastic particles ≤1 µm). Nanoplastics pose unique sample collection and analytical considerations that have limited their detection in the environment, while a lack of environmentally relevant nanoplastic test materials creates a barrier to conducting representative exposure and effect studies. To address these challenges, there is an urgent need to develop a relatively simple and robust method for generating nanoplastic particles representative of those in the environment.
Description:
While the pervasiveness of plastic pollution in the environment is well-established, little is known regarding the extent, distribution, and effects of the smallest size fraction, referred to as nanoplastics (generally considered to be plastic particles ≤1 µm). Nanoplastics pose unique sample collection and analytical considerations that have limited their detection in the environment, while a lack of environmentally relevant nanoplastic test materials creates a barrier to conducting representative exposure and effect studies. To address these challenges, there is an urgent need to develop a relatively simple and robust method for generating nanoplastic particles representative of those in the environment. The aim of this work was to develop a “top-down” approach for producing environmentally representative plastic test materials throughout the microplastic (>1 µm to ≤5 mm) and nanoplastic (≤ 1 µm) size ranges. Weathered marine macroplastic samples encompassing a range of polymers (including LD-/HDPE, PP, PS, PET, and Nylon) and waste electronic and electrical equipment (WEEE, sometimes referred to as “black plastics”) were chosen as environmentally-representative feedstock materials. Commercial-grade polymers (including LD-/HDPE, PP, PS, PET, Nylon, PEST, and ABS) were selected to serve as control materials to help identify methodological artifacts. Each feedstock material was individually cryomilled, bath sonicated, and then vacuum-filtered (1 µm PTFE) to generate and separate the micro- and nanoplastic particles. A variety of analytical techniques were used to characterize the materials at the different processing stages, including Fourier-transformed infrared spectroscopy (FT-IR), pyrolysis gas chromatography mass spectrometry (py-GC-MS), scanning electron microscopy (SEM), dynamic light scattering (DLS), and nanoparticle tracking analysis (NTA). Overall, the approach was found to effectively generate both micro- and nanoplastic particles. Higher yields were observed with the environmentally-representative feedstock materials compared to the commercial-grade polymers. The physical characteristics of the microplastic materials were generally consistent across the polymer types, typically fragments or flakes between ≈1 – 100 µm in size with rough, heterogenous surface features. The nanoplastic materials displayed more uniform shape and size characteristics, typically fragments between ≈100 – 300 nm in size. Chemical characterization (FT-IR and py-GC-MS) to identify methodological artifacts will also be presented. Disclaimer: This abstract does not reflect U.S. EPA policy.
