UK researchers develop biopolymer recycling technique

Scientists at the Universities of Birmingham and Bath in the United Kingdom say they have developed a “faster, more efficient way” of recycling plant-based biopolymers or bioplastics. The research was funded by the U.K.-based Engineering and Physical Sciences Research Council.

The research team says its chemical recycling method not only speeds up the process, but can convert discarded bioplastics into a new product—a biodegradable solvent—that “can be sold for use in a wide variety of industries including cosmetics and pharmaceuticals.”

Bioplastics, made from polylactic acid (PLA), are used in products including disposable cups, packaging materials and toys. Typically, once they reach the end of their useful life, they are disposed of in landfills or composted, biodegrading over periods of up to several months, say the researchers.

The newly-developed chemical process uses a zinc-based catalyst developed at the University of Bath and methanol. The solution can be used to break down consumer plastics and produce the solvent, called methyl lactate. A description of the process and the research results have been published in the Washington-based journal Industrial & Engineering Chemistry Research.

The method was applied to three separate PLA products– a disposable cup, some 3D printer scrap, and a toy. The team found the cup was most easily converted to methyl lactate at lower temperatures, but even the bulkier plastic in the toy could be converted using higher temperatures. “We were excited to see that it was possible to obtain high quantities of the green solvent regardless of samples’ characteristics due to colorants, additives, sizes and even molecular weight,” says lead author Luis Román-Ramírez of the University of Birmingham’s School of Chemical Engineering.

“The process we’ve designed has real potential to contribute to ongoing efforts to reduce the amount of plastic going into landfill or being incinerated, creating new valuable products from waste,” says lead researcher Professor Joe Wood, of the University of Birmingham.

Adds Wood, “Our technique breaks down the plastics into their chemical building blocks before ‘rebuilding’ them into a new product, so we can guarantee that the new product is of sufficiently high quality for use in other products and processes.”

Next steps would involve scaling up the process further to see it can be used in an industrial setting.