A new path for recycling polystyrene waste that uses light, an oxygen-rich environment, and an abundant iron-based catalyst, has been discovered by researchers at the College of Arts & Sciences at Cornell University (Ithaca, New York, USA; www.cornell.edu). A research paper on the recycling method, Chemical Upcycling of Commercial Polystyrene via Catalyst-Controlled Photo Oxidation, was published in the Journal of the American Chemical Society by the American Chemical Society (Washington, D.C.; www.acs.org).

The process to recycle waste PS, a material that makes up a third of the landfill waste worldwide, includes it being upcycled into benzoic acid and other products that can be repurposed, according to Erin Stache, assistant professor of chemistry and chemical biology at Cornell.

The researchers applied a catalyst-controlled photooxidative degradation method, where the PS sample in acetone is exposed to LED light in an oxygen-rich environment using an iron chloride catalyst for 20 hours.

Researchers in Stache’s lab found the PS recycling process to be mild, climate-friendly, and scalable to commercial waste streams. The process is tolerant of additives inherent in a flow of consumer waste, including dirt, dyes, and other types of plastics. Degradation tests showed that sunlight could be harnessed by some of the catalysts they’ve developed at the lab to achieve good control over the chemical process. The researchers also tested the tolerance of the process to other materials mixed with PS plastic, ranging from packaging materials to coffee cup lids.

The testing results “signify that our system could efficiently break down commercial samples of PS, even with additional composite and insoluble material”, Stache said. The process is suited for use with waste polystyrene in a wide range of forms, use, and textures, from styrofoam to hard jewel cases.