16-Jul-25 An Australian research team has reported a way to erase 90% of throw-away plastic like styrofoam (expanded polystyrene) in just thirty minutes, using nothing more than air, purple light, and a pinch of table-grade chemicals.
Dr. Maxime Michelas of the University of New South Wales School of Chemical Engineering (UNSW), working with colleagues in the School of Chemistry and CSIRO, describes the method in a recent study.
Their approach slices stubborn polymers into bite-size molecules that industry already uses to make solvents, coatings, and flavors.
Michelas’ team turns low-cost salt iron trichloride into an aggressive photocatalyst.
When a 405-nanometer LED excites the salt, it spawns chlorine radicals that yank hydrogen atoms off the polymer backbone.
The orphaned carbon grabs oxygen from the air, the chain snaps, and the plastic’s mass plunges.
The setup looks almost rudimentary. A glass flask sits on a stir plate, air or pure oxygen bubbles through a dichloromethane solution of shredded plastic and five mole percent catalyst, and a small LED panel shines from the side.
Under those conditions the authors report a 90% mass loss for seven commodity polymers in half an hour.
Extending exposure to three hours pushes conversion to 97%, a milestone that once demanded day-long lamp times.
For the fastest substrates, including poly(ethylene oxide) and poly(methyl acrylate), most bond-breaking happens in the first ten minutes.
Even polyvinyl chloride, notorious for its tight packing and limited solubility, gave up seventy-eight percent in the half-hour window.
“I think it’s very important to degrade the polymer and turn it into another feedstock we can use for other things, or just to reduce the amount of microplastics in the world,” noted Dr. Michelas.
Breaking chains is only half the story. Gas-chromatography traces reveal a soup rich in small aldehydes and carboxylic acids that can feed into paint, adhesive, or fragrance manufacture with little additional purification.
Because the catalyst is iron and the reaction runs near room temperature, the energy bill looks minimal compared with pyrolysis or incineration.
The group demonstrated a fifty-gram-per-liter run that held over eighty-five percent efficiency, then regained speed simply by bubbling in fresh oxygen when the gas was spent.
A 2023 case study of a decentralized pyrolysis unit showed that processing 360 tons of mixed plastic per year demanded about 560 MWh of electricity, or roughly 1,550 kWh for every ton treated.
That figure dwarfs the LED-lit UNSW setup, which relies mainly on ambient heat and the modest power draw of a few lamps.
Slashing kilowatt-hours per ton means smaller carbon footprints and lower operating bills, especially in regions where electricity still comes from coal.
For context, running a fifteen-watt LED strip for half an hour consumes about 0.015 kWh, orders of magnitude below even the leanest pyrolysis benchmarks.
Venture groups in Australia and Singapore have already begun scouting pilot-scale demonstrations, according to the authors.
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