A Styrofoam (polystyrene plastic) take‑out food box can outlive its owner and their children.
It weathers rain, sunlight, and curbside crushes yet still hangs around, splintering into smaller shards instead of disappearing. An Australian research team now reports a way to erase 90% of that throw‑away plastic in just thirty minutes, using nothing more exotic 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.
Polystyrene plastic linger for centuries
Humanity produces more than four hundred million tons of plastic per year, and the figure keeps climbing even where recycling programs thrive. Most items are designed for single use, yet their bonds resist microbial attack and sunshine alike. Polystyrene poses a special headache. The foamed version is restricted in several U.S. states, yet analysts expect global demand to reach sixty‑two million tons within a decade. Its light weight means flakes travel far on the wind, then fracture into microplastics that slip through standard filters and into drinking water. Surgeons have even found plastic fragments embedded in arterial plaque removed from heart patients. Michelas’ team turns the 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.
Dissolving plastic by 90%
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.
Savings for cities and companies
Foamed polystyrene can occupy up to thirty percent of landfill volume by space, prompting bans in California, Maine, and Maryland that steer eateries toward plant‑based or recyclable packaging. Yet many municipalities still receive tons of foam, paying transport costs on material that weighs almost nothing but swallows cubic yards. A low‑temperature, bench‑scale unit could let waste haulers liquefy that foam onsite, drain the product into drums, and sell it to chemical distributors. By tackling items most prone to shedding, like takeaway containers, the UNSW chemistry could noticeably dent that intake. Though the catalyst cannot vacuum particles already loose in rivers, less fragmentation upstream means fewer specks small enough to cross gut or lung barriers. Lower exposure could reduce inflammatory burdens now documented in lab studies, easing growing public‑health worry.
News Courtesy : Earth.com