We are facing our biggest environmental challenge, plastic pollution. The most commonly used PET plastic is everywhere and only 30% of these can be recycled mechanically. To increase this rate, researchers are looking for chemical processes that could recycle common plastic waste.
The Virginia Tech research team led by Ph.D. candidate Adam McNeeley and Alumni Distinguished Professor Y. A. Liu discovered a chemical process to accurately recycle common plastic waste, like polyethylene terephthalate (PET). Their work provides a comprehensive assessment of the thermodynamics, chemistry, purification, waste management, and sustainable design of PET depolymerization processes.
The researchers created a simulation model quantifying the mass and energy balances, energy demand, and carbon dioxide emissions for four depolymerization processes, providing a quantitative foundation for industrial practitioners.
“There are many different ways PET can be depolymerized and there are three that are being actively developed for commercial use, and we demonstrate how these different methods compare from a chemical processing standpoint,” says McNeeley.
Key Highlights: Chemical Process Helps Recycle Plastic Waste
- Analysis of 3 main chemical recycling processes, glycolysis, methanolysis, and hydrolysis.
- Glycolysis was the least energy-intensive process, perhaps due to easier purification.
- Methanolysis shows accuracy when the ongoing process of purification was complex.
- Hydrolysis turns out to be the most complex and energy-intensive process.
- Analyzed depolymerization pathways using ethylene glycol, methanol, or water to produce monomers that can be purified and converted back into recycled PET polymer.
“The importance of this research is to identify and develop the cheapest and most efficient ways to recycle PET, There is a clear public desire to use products made from recycled materials, but if the recycled material costs a lot more than the virgin material, then people are less likely to buy the recycled material.” says McNeeley.
Opportunities of the Study
- Chemical depolymerization opens up various purification pathways, allowing for the recycling of PET waste of theoretically any quality, including packaging and textiles, which comprise the majority of PET end-use.
- Companies like Eastman Chemical Co. are actively developing PET chemical recycling technologies, with the first large-scale depolymerization unit in the United States using methanolysis already built in Kingsport, Tennessee.
Have you heard about that a man recycles dry waste and offers rewards in return?
Limitations of the Process
- Mechanical recycling cannot remove certain dyes and impurities from PET waste.
- Some processes have equilibrium limitations that reduces product yield.
- High temperatures can cause degradation and formation of unwanted by-products.
- Separating solvents like methanol and ethylene glycol from products is energy-intensive.
Researchers conclude that it is possible that chemical processes could recycle common plastic waste. However, there is still some work to do to overcome the challenges faced during the process.
Source: Researchers analyze how a chemical process could help recycle a common plastic waste
