Generation of Light-Absorbing Carbonaceous Aerosol from Thermal Degradation of Plastics and Whitening through Atmospheric Aging

ASMA SOOFI, Katrina Betz, Jace Barton, Elijah Schnitzler, Oklahoma State University

     Abstract Number: 230
     Working Group: Carbonaceous Aerosols

Abstract
Plastic incineration is a growing source of carbonaceous aerosol, which can impact air quality, visibility, and the radiative balance of the atmosphere, through scattering and absorbing radiation and altering cloud formation. Previously, we have shown that light-absorbing carbonaceous aerosol generated from the heated nozzle of a 3D printer can undergo whitening upon exposure to simulated sunlight and gas-phase ozone, with implications on role of this aerosol in the atmosphere. Here, we extend this effort to explore the formation and fate of carbonaceous aerosol from plastic pollution by generating carbonaceous aerosol from thermal degradation of plastic, i.e., polyethylene terephthalate glycol (PETG) and acrylonitrile butadiene styrene (ABS), in a tube furnace and monitoring changes in the color and absorbance of filter-collected samples upon aging processes in the laboratory. Carbonaceous aerosol was generated at furnace temperatures between 300 and 500oC, in 50-degree increments, from both colorless and colorful PETG. At low furnace temperatures, colorless and blue PETG both gave colorless carbonaceous aerosol, while red PETG gave red aerosol. At 450oC, all bulk PETG gave light-absorbing organic aerosol, or brown carbon (BrC). At 500oC, bulk PETG began to give black carbon (BC), from flaming combustion. Filter-collected nanoparticles were exposed to light from a Xe lamp in a solar simulator for up to four days. The absorbance of the samples at visible wavelengths was monitored in 24-hour intervals, indicating significant changes in light absorption with aging. Additionally, composition of the aerosol was monitored using attenuated total reflectance (ATR) Fourier-transform infrared spectroscopy before and after aging and compared to the bulk materials. These results help further the community’s growing understanding of the formation and fate of carbonaceous aerosol from plastic pollution.