‘Yellow chemistry’ turns sulfur waste into plastics – Science Nation


♪ MUSIC ♪ MILES O’BRIEN: Many labs now work on “green” chemistry, fewer toxins and better for the environment. But here’s one you’ve probably never heard of, “yellow” chemistry. JEFF PYUN: So because sulfur’s yellow, we think of creating a whole new field basically from yellow chemistry or yellow plastics. Sulfur is basically a waste product from petroleum refining, so there’s tons of it around. MILES O’BRIEN: With support from the National Science Foundation, chemist Jeff Pyun and his team at the University of Arizona are putting sulfur to work making plastic batteries, even optical and imaging devices.  He says oil and gas production generates 70 million tons of sulfur every year. Most of that goes to make sulfuric acid and fertilizer. But there’s still millions of tons left over. JEFF PYUN: Sulfur is really hard to work with. It’s hard to do conventional chemistry with it, and so it’s basically something that nobody really wanted to invest in, and so just out of pure frustration we basically had the idea, let’s just melt this damn stuff, see what goes into it, and sure enough, you know, that was really the key breakthrough for us. MILES O’BRIEN: In the end, they mixed up an amazingly simple chemical recipe for sulfur-based plastic. And they can mold it into all sorts of things: toys, lenses, even a 45-record! JEFF PYUN: They basically made a mold of this and basically made a sulfur record! ♪ MUSIC ♪ MILES O’BRIEN: Lithium-ion batteries currently power many of our electronics, but sulfur batteries could change that. Pyun imagines sulfur-based electric car batteries that would be lighter, cheaper and hold four or five times the charge we’ve come to expect. RICHARD GLASS: There are so many other applications that one found with this–it’s just remarkable. It’s opening up a whole new area of polymer chemistry. ROBERT NORWOOD: So, basically it is a completely different type of optical plastic for infrared. MILES O’BRIEN: Initially a skeptic, optical scientist Robert Norwood sees big potential in sulfur-containing night vision devices, thermal monitoring sensors and medical imaging hardware. ROBERT NORWOOD: So that’s the connection. Sulfur winds up having a higher refractive index, which allows you to make some interesting lenses out of them for infrared light, one of the key considerations for something like night vision goggles. MILES O’BRIEN: Pyun says the possibilities are nearly endless. JEFF PYUN: So basically, how do we sort of increase the cookbook, the recipes of things that we can do because we’ve just nicked the surface really from the science standpoint of what you can make with sulfur. MILES O’BRIEN: So, at the risk of piling it on, we might think of this as a “golden” opportunity. For Science Nation, I’m Miles O’Brien.

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