Oxygenating Plastic Waste Pre-Treatment with Non-Thermal Plasma-Liquid Interactions

The proliferation of plastic waste is of global concern, with only ~9% recycled. Due to this, chemical recycling methods, where the waste is chemically broken into smaller carbon fragments for reproduction or production of other high value product streams, have been of great scientific interest. Non-thermal plasma is possible to aid in this recycling process as a pre-treatment step, providing surface oxygenation that can alter product distribution after downstream thermochemical processing, for example with pyrolysis. In water, high hydroxyl radical densities and other oxygenates may provide enhanced surface modifications. This work explores the use of an underwater corona discharge and an atmospheric pressure plasma jet submerged in water for surface modification to a variety of common plastic powders (e.g. polyethylene, polypropylene). Surface modifications are determined with ATR-FTIR and XPS, while product characterization is conducted post-treatment for aqueous and gas phase species produced. Finally, a pyrolysis treatment of the dried, treated plastic powders is conducted to compare product distribution (primarily C1-C3s, hydrogen, and oxygenated intermediates).