CAREER: Detailing the mechanism of plasma-mediated oxidative depolymerization of plastics to chemicals by metal-organic frameworks in liquid water at ambient temperature

A central problem in plastic recycling is that current processes yield low-value products, making plastic recycling economically unattractive. This CAREER project seeks to improve understanding of a new plasma-based upcycling process for transforming discarded plastic into valuable products, helping to mitigate the ever-increasing plastic pollution that negatively impacts the environment and health of the world’s population.

The objectives of this research program are to analyze the mechanism whereby a plasma (consisting of charged particles) breaks down plastic in ambient-temperature water in the presence of a catalyst to produce carboxylates, a group of oxygen-containing organic chemicals that can readily be used to produce high-value materials. This research will lay the groundwork for transforming a broad range of discarded plastic into high-value chemicals, working toward a circular end-of-life approach for dealing with plastic pollution.

The transformation process uses a low-energy plasma generator that can be powered by renewable electricity from wind and solar sources, making the process economically viable and reducing its carbon footprint. This research will be integrated with educational and outreach programs to increase engagement of underrepresented minorities and women in STEM, and to educate both STEM and non-STEM majors about chemical processes that can benefit the environment.

These activities will emphasize the importance of plastic upcycling for a healthier environment and a sustainable society.

Common plastic for packing, such as polyethylene, polypropylene, and polystyrene, is inert and capable of withstanding high temperature. Thus, derivation of useful materials from waste plastic normally requires energy-intensive measures, such as pyrolysis, that convert plastic to alkane-like compounds. The objective of this project is to develop an alternative approach to plastic conversion based on a catalytic plasma-mediated depolymerization process that operates at ambient temperature and in liquid water.

This process begins with modification of the waste plastic surface to increase its wettability and to reduce the polymer backbone C-C bond strength, followed by plasma-mediated depolymerization in the presence of a metal-organic framework catalyst. The proposed research seeks to 1) measure the effects on plastic depolymerization activity of the type and extent of surface functionalization with sequence of polar groups, and 2) detail the mechanisms of plasma-assisted depolymerization and analyze selectivity towards carboxylate products.

The project’s education plan centers on developing an innovative interdisciplinary undergraduate course, “Giving Life to Discarded Plastics” designed for STEM and non-STEM majors and incorporating the SODOTO (See-One-Do-One-Teach-One) method of teaching to build student engagement, communication, and teamwork skills. In addition to the course, the principal investigator will institute summer programs that introduce chemistry concepts to students with diverse backgrounds, emphasizing how chemistry can help address environmental problems, focusing on the benefits of plastic upcycling, and helping to inspire interest in STEM careers.

The course and summer initiatives will expand the PI’s on-going efforts to recruit underrepresented minorities, women, and underprivileged students at the secondary level.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.