Turning Plastic Into Soap with Guoliang Liu

In 2023, plastics permeate even the furthest reaches of our world. It’s been found in the deepest parts of our oceans and within our own bodies. With all of this new and sometimes scary research coming to the surface, some hopeful solutions are making headlines as well. 

In an exclusive interview with Guoliang Liu, CleanUp News learned of what could be the next major method of combating plastic waste; turning it into soap (and other useful chemicals). 

The ingenious solution was hatched fireside on Christmas. Liu, an associate professor of chemistry at Virginia Tech, was inspired by the smoke and wondered if he could create a usable substance by safely heating up plastic.

“We have these piles of waste lying around that we don’t know what to do with,” Liu told CleanUp News over a Zoom conversation. “So I thought, why don’t we just treat them as a crude oil at a refinery?”

The process involves heating up polyethylene and polypropylene (two of the most heavily used types of plastics) to 360°C in a reactor until the molecules break from their chains. These wax-like molecules are then caught at the cooler top of the reactor, where the temperature difference stops them from fully evaporating. Afterwards they are transferred to a new reactor where they are heated/oxidized, turned into fatty acids, and then finally, neutralized. The result is a surfactant, which can be used for a myriad of useful products, including soap and lubricants. 

Naturally, we had a lot of questions. With the plethora of research on microplastics and harmful plastic additives that has emerged in the last few years, we wanted to know if this soap was just another culprit. Liu was happy to tell us not to worry– “At 360°C plastic molecules cannot evaporate. Theoretically the finished product should not have any microplastics.” 

Liu went on to tell us that his team has tested the temperatures at which they can separate contaminants from their final product, and at high temperatures the additives are unstable and break apart (which in this case, is a good thing). “There may still be trace amounts which would require further purification, but that’s pretty standard in the chemical industry,” Liu told us.

Liu and his team are also trying to tackle some major problems that, until now, haven’t had much leeway in terms of solutions. “Another major form of waste our lab is working with is polystyrene foam… usually it is forbidden to recycle this material. So we figured out we can break polystyrene apart and harvest the most important parts, like the aromatics, which can be used to make new compounds.” Liu went on to excitedly tell us that these new compounds can be used in cosmetics, fragrances, and drug precursors. “In this way, we can utilize a really cheap, low-cost waste, and produce high-value chemicals.”

Liu wanted to make clear that his lab is not incinerating plastics. The molecule chains are breaking inside their reactors, but are not turning into gas. Thus, the harmful discharge potential is significantly reduced compared to pyrolysis, which can produce various toxic gasses. 
One thing is for sure– it is relieving to hear some good news about plastic. You can follow what Guoliang Liu and his team are up to on their website, The Liu Group: Polymers and Nanomaterials. Stay vigilant out there!

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