In a tremendous development in sustainable materials science, Virginia Tech researchers have invented a method to recycle plastic waste into soap and detergents. The global plastic pollution crisis is being addressed through this process led by Associate Professor Guoliang ‘Greg’ Liu and his team.
The Process | From Plastic to Soap
The team’s approach centres on the chemical similarity between polyethylene, a chemical precursor of the plastic polyethylene, as found in milk cartons and plastic bags for instance, and fatty acids which are a precursor to soap. In both cases the long carbon chains are attached to an additional group of atoms at one end, including fatty acids. The researchers heated polyethylene to break its long chains into shorter segments and then very quickly cooled the material to produce wax like substances. These waxes were then decomposed to soap in subsequent steps, including saponification.
Liu explained:
Firewood is mostly made of polymers such as cellulose. The combustion of firewood breaks these polymers into short chains, and then into small gaseous molecules before full oxidation to carbon dioxide
If we similarly break down the synthetic polyethylene molecules but stop the process before they break all the way down to small gaseous molecules, then we should obtain short-chain, polyethylene-like molecules.
Economic and Environmental Implications
Not only does it serve environmental aims, but it also provides economic advantages. The average price of soap and detergent is around 
1,150 per metric tonne on average. The price differential is enough to make it economically attractive to convert plastic waste into soap, perhaps even to encourage recycling.
Broader Applications and Future Prospects
The technique is also applicable beyond polyethylene, for example to polypropylene, another common plastic utilised in a variety of consumer products. Notably, the process also does not require the type of meticulous plastic sorting required by traditional recycling methods, yet it is also able to process mixed plastic, another useful asset. With the simplicity of the process as it is simple, only requiring plastic and heat, its scalability and accessibility will be a plus for recycling initiatives everywhere.
Lead author Zhen Xu noted:
Our research demonstrates a new route for plastic upcycling without using novel catalysts or complex procedures. In this work, we have shown the potential of a tandem strategy for plastic recycling
By example, the work of Liu and his team demonstrates how chemical engineering can be innovative toward sustainable solutions for plastic waste. This research provides a real potential for stopping environmental pollution with low effort by turning waste plastics into value added products such as soap, while spurring economies into recycling. This method holds promise for making a meaningful contribution towards the global plastic waste management as the method advances towards commercialization.
