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Houston researchers develop heating method to recover critical minerals from e-waste

The world is trending toward producing 82 million metric tons of flame-retardant plastic waste by 2030. Photo via Unsplash

Researchers at Rice University have developed a new technique to efficiently recycle electronic waste and harvest critical minerals using rapid heating.

Most electronic devices use flame-retardant plastic. The plastic is formulated from a critical metal called antimony.

However, recapturing antimony is typically a challenging task since it first has to be released from the plastic. As it is released, other compounds can form, such as organic bromides, which are toxic and difficult to capture. However, the organic bromides can also be reused and have applications in industrial chemicals when safely captured.

“Conventionally heating the plastic releases the antimony in a volatile and difficult-to-collect form as well as creating and releasing hazardous organic bromide compounds,” Leo Haoxin Ye, first author of the paper and a graduate student at Rice, said in a news release. “Other options are risky or more impractical, such as using strong acids, organic solvents or multistep treatment options.”

To address this issue, leading Rice chemistry professor James Tour, Ye and their team adapted Tour’s flash Joule heating technique, which heats materials to hundreds of degrees Celsius in milliseconds, according to Rice.

The team ground up flame-retardant plastic waste and placed it between two sheets of electrically heated carbon paper before using what’s known as isothermal-clamped flash Joule heating to release and collect the antimony.

The team found that limiting the time the plastic spent in the high temperature range dramatically reduced the production of the hazardous organic bromide compounds. The plastic remained between 200 degrees and 500 degrees Celsius for only 9.4 milliseconds, according to Rice.

Through the process, the team recovered 90 percent of antimony from tested materials and converted 83 percent of the bromide into hydrogen bromide. Their findings were published this month in the journal Nature Chemical Engineering.

“Isothermal-clamped flash Joule heating could improve the speed, safety and practicality of antimony recovery from discarded flame-retardant plastics,” Tour added in the release. “This represents an important step forward to conserving and reusing our critical antimony supply while also regenerating bromide salts for reuse.”

The study noted that the world is currently trending toward producing 82 million metric tons of flame-retardant plastic waste by 2030, which adds to the fact that e-waste is the fastest-growing solid waste stream in the world.

The research was funded by the Air Force Office of Scientific Research and the U.S. Army Corps of Engineers.

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A View From HETI

Tesla sales were down yet again. Getty Images

Tesla has unveiled its new Roadster sports car, which can thrust itself in the air, among other engineering bells and whistles. But drivers shouldn't expect to take it for a spin anytime soon.

Elon Musk's electric car company rolled out its second-generation Roadster at a Thursday event, showing off a set of cold gas thrusters and a “multi-mode” suction system that can fling the car in the air for short spurts and spin the vehicle mid-flight.

“Turns out the future does have flying cars,” Musk, Tesla's CEO, wrote on his social media platform X shortly after.

That future could be a ways off, however, given the regulatory hurdles for flying vehicles and the tangle of state rules that still need to be met.

“I’m not sure every state is going to allow a driver in the middle of traffic to suddenly elevate himself and fly," said David Vladeck, a Georgetown Law professor and former director of the FTC’s Bureau of Consumer Protection. “There is going to be a long process to let anything like that on a road.”

Thursday's event was hosted at the Texas rocket testing and development center for SpaceX — Musk's publicly-traded rocket company — and Tesla's executives noted that they “borrowed” some SpaceX technology to get the new Roadster in the air. Beyond quick jumps and flips, Tesla also said the car can accelerate from zero to 60 miles (96.6 km) an hour in less than a second.

This launch arrived after years of delays and anticipation around the new Roadster — and Tesla shares climbed in morning trading on Friday before falling amid a sell-off in companies tied to artificial intelligence.

The wait isn't completely over. Musk said production for consumers won't begin until 2028. Tesla also didn't immediately set a price tag on its latest EV.

Tesla was taking reservations for Roadster “rocket” car purchases on its website Friday morning, though the fine print said there was no guarantee when the vehicle would be delivered — or whether it would be delivered at all.

Bryant Walker Smith, former vice chair of a Department of Transportation advisory group on innovation, was unimpressed — though he did note Musk's ability to keep Tesla's stock high.

“This was a demonstration of a one-off car using a technology around for many years and will not be coming to public roads in 2028," said Smith, a law professor at the University of South Carolina. “Tesla pretty uniquely has been able to sell itself on a future that is an order of magnitude greater than reality.”

Musk has repeatedly said that the future of driving will be autonomous — and Austin-based Tesla has focused much of its business on building out self-driving features for its vehicles and, more recently, launching its own (still limited) robotaxi business.

But the company maintains that the Roadster will be made to have humans behind the wheel, calling the EV the “best of the last human-driven cars.”

Thursday's demo was technically autonomous “to make sure we don’t kill anyone,” Musk noted. But long-term, he said, the new Roadster will be “the only manually driven car that Tesla makes.”

“This is not necessarily a safety-optimized car,” Musk later added, met by laughter from the audience. But “it takes the fun meter to 11 out of 10.”

Tesla's first Roadster was launched back in 2008. And in 2018, Musk went as far as placing one on a rocket — with a mannequin dubbed “Starman” in the driver's seat — and launching it into space.

Again, the second-generation Roadster isn't immediately hitting the market. And whether the ambitious new vehicle boosts the company's bottom line remains to be seen.

In second-quarter earnings reported over the summer, Tesla's profits fell as the company spent more on research and development for its robotaxi and robotics businesses — which cut into money made from an otherwise sharp increase in vehicle sales. Net income totaled $1.11 billion for the period, while revenue climbed to $28.24 billion.

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