A way was found to collect plastic waste such as milk cartons, food containers and plastic soap bags. This achievement is thanks to a team of researchers from the Virginia Tech Department of Chemistry in the United States, who discovered an amazing way to recycle.
This finding represents an important advance in the search for sustainable solutions to reduce the environmental impact of plastic waste. In the treatment of plastics, the long carbon chains are heated and then rapidly cooled. This process helps change the molecular structure of plastics and improve their physical properties.
Plastics and soaps differ greatly in terms of their nature, their appearance and, above all, their function. Plastics are solid and durable materials used primarily to make durable items, while soaps are liquid or solid substances used for personal cleanliness and hygiene. Although they may seem opposite in many ways, both play an important role in our daily lives.
Similarities between polyethylene and soap
There is undoubtedly an intriguing relationship between the two elements at the molecular level. It turns out that the chemical structure of polyethylene, a very common type of plastic, bears striking similarities to that of a fatty acid used as a base in soap making.
Both materials are made up of long carbon chains, but fatty acids have an extra group of atoms at the end of the chain.
A research group from Virginia Tech (USA) has developed a new method to recycle plastics and convert them into valuable substances called surfactants (also known as surfactants). This innovative technique could help reduce pollution caused by plastic waste while preserving high quality products used in soaps, detergents and other products.
The key: shorten carbon chains
According to Guoliang “Greg” Liu, associate professor of chemistry at Virginia Tech’s College of Science, the similarity between the materials suggests it’s possible to convert polyethylene into fatty acids. Liu was faced with the challenge of converting a long chain of polyethylene into several shorter chains, and he was sure he could find an efficient way to do it, using upcycling (materials reused for a second life) to reuse low-waste plastics.
To find the answer, Liu thought about fire and combustion. The possibility was raised of what would happen if polyethylene could be incinerated in a controlled laboratory environment.
If the polyethylene burns incompletely, Liu argues, smoke could be produced, possibly containing damaged polymers in shorter chains. These chains would turn into small gaseous molecules before being fully oxidized to carbon dioxide (CO2).
The process of turning plastic waste into soap
“If we break down the synthetic polyethylene molecules in this way, but stop the process before they completely break down into small gaseous molecules, we should end up with short-chain polyethylene-like molecules.“, Add.
The chemist commissioned Zhen Xu and Eric Munyaneza, two graduate students from his lab, to collaborate to build a furnace-shaped reactor. This device made it possible to heat polyethylene through a process known as thermogradient thermolysis. A high temperature is reached in the lower part of the furnace, which allows the polymer chains to be broken and decomposed. Meanwhile, it is cooled to a low temperature at the top of the kiln to stop this decomposition process.
After performing the thermolysis, the residues were collected, similar to cleaning soot from a chimney. Surprisingly, it was found that these residues mainly consist of short-chain polyethylene, more specifically waxes.
After this first step, some additional processes such as saponification were carried out to achieve the production of the first plastic soap. This breakthrough marks an important milestone in the development of environmentally friendly and innovative solutions to reduce plastic waste and promote the circular economy.
Sustainable goals for recycling plastic waste
To improve the recycling process and share it with the scientific community, the team drew on the expertise of experts in computer modeling and economic analysis, among others. This approach allowed us to refine the process and aim for more sustainable goals.
“Our research shows a new way to recycle plastics without using novel catalysts or complex processes. In this work, we have demonstrated the potential of a common strategy for recycling plastics‘ points out Xu, co-author of the article.
“This will help people come up with more creative upcycling practices in the future.“, shows.
cheap war on pollution
This project is based on using polyethylene as the main plastic, but the recycling process can also be applied to polypropylene. These two types of plastic are commonly used in food packaging and textiles, and make up a large portion of the plastic that consumers interact with on a daily basis.
One of the interesting advantages of this type of reuse is that both types of plastic can be used at the same time, eliminating the need for prior separation. This facilitates the process and saves time when disposing of plastic waste.
In fact, this technique is quite easy to perform. Only plastic should be available and heat applied. No large resources or complicated processes are required.
While the subsequent steps of the process require some additional conditions to convert the wax molecules into fatty acids and soap, the initial conversion of the plastic is a fairly simple process. According to those responsible for the article, this not only helps to make the method cheaper, but also has a relatively low environmental impact.
The value of the end product
In addition, it is critical to the large-scale success of the transformation method that the end product be of sufficiently high value to recover the cost of the process and make it commercially attractive. Although soaps do not appear expensive at first glance, they can actually be significantly more expensive than plastic products when compared by weight. It is important to consider this factor when purchasing to ensure we are getting the best value for money.
Liu says this research lays the groundwork for a new way to reduce waste by channeling used plastics into the production of other useful materials.
For his part, Xu points out that ““Plastic pollution is a global challenge and not a problem for a few dominant countries,” so “a simple process may be more accessible to many other countries around the world.”“.
After all, he assumes that this is a “Good start in the fight against plastic pollution“.
Liu, G et al. “Chemical upcycling of polyethylene, polypropylene and mixtures to high-quality surfactants”. Science (2023).
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