How to Recycle Plastics

The Science Behind Why You Should Ask For Help

Sometimes asking for help—even for the smallest of favors—can feel awkward, or like you’re inconveniencing someone else. But the odds are, you’re probably wrong. Studies show that people are much more willing to lend a helping hand than you would think, and both parties usually end up happier.

Guest host Shahla Farzan talks with Dr. Xuan Zhao, a psychologist at Stanford University, about the psychology behind asking for help.

 

A Possible Achilles Heel For Troublesome PFAS Chemicals

Long-lasting chemicals known as per- and polyfluoroalkyl substances, or PFAS, are used widely in everything from firefighting foam to microwavable popcorn bags. The chemicals are a popular component of polymer coatings that resist heat, grease, stains and water.

PFAS compounds (a family that includes roughly 12,000 different substances are often called “forever chemicals” in popular science coverage, because they’re designed to be super stable and don’t break down in the environment. But what makes them last “forever” from a chemistry perspective? And what can we do about it?

Current PFAS disposal methods are expensive and labor-intensive, blasting the chemicals with temperatures over 1,000 degrees C in a high-pressure environment. But a research study published in Science has found a possible Achilles’ heel: a weak spot in the chemical bonds. The research points to a new possible method for disposing of PFAS chemicals, which uses special reagents to knock off a group of oxygen atoms at the tail end of PFAS, triggering a cascade of reactions that breaks the PFAS chemicals down into harmless components.

The paper’s lead author, Brittany Trang, joins guest host Shahla Farzan to discuss this development in PFAS research.

 

Engineered Bacteria Might Help The Dream Of Mixed Plastic Recycling

We’ve all been there—standing by the recycling bin, holding some sort of plastic object, and trying to figure out if it can go in the bin.

There are many different types of plastic out there, from the film that wraps the meat at the grocery store, to the plastic in your milk jug. But they all differ in their ability to be recycled, and in the specific procedures and recipes that it takes to process them. Writing in the journal Science, a team of researchers describes a demonstration process that can break down a mixed bag of plastics, even dirty ones, and produce a single chemical output that could be used in industry.

The process starts with a catalytic oxidation process involving metal salts, an acetic acid solvent, heat, and oxygen. That process is essentially a “controlled combustion,” says Dr. Gregg Beckham of the National Renewable Energy Laboratory. The oxidation process breaks the plastics in the reaction into a blend of liquid chemicals. Then, that blend of products is fed to a strain of engineered bacteria that have been designed to be able to eat each of those chemical breakdown products, and use them to make a specified product.

Beckham says that in the initial experiment, they created two different products—one a biodegradable plastic, and one a precursor to a type of recyclable nylon—but the method could conceivably be adapted to any product that bacteria can be enabled to grow via synthetic biology. Beckham joins SciFri’s John Dankosky to talk about the demonstration, and the challenges of moving this technology out of the laboratory and into an operating recycling process.

 

How Understanding Depression Goes Beyond The Scientific Method

Science has yet to pinpoint exactly why some people experience depression and others do not. And it may never be able to give a fully satisfying answer. While people with depression may have similar symptoms, each person’s story is just a little different. And there’s no “one size fits all” treatment.

Guest host John Dankosky talks with John Moe, who has spent a lot of time thinking about the nuances of depression through a humorous lens. Moe is the host and creator of the podcast Depresh Mode and author of The Hilarious World of Depression, which shares a name with his previous podcast. 

 

Transcripts for each segment will be available the week after the show airs on sciencefriday.com.

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