American scientists have discovered a way to turn used plastic into soap.
According to The Guardian (UK), plastic has chemical properties similar to fatty acids, which are one of the main ingredients of soap. This similarity could help us convert polyethylene into fatty acids, which we then use, said Guoliang Liu, an associate professor of chemistry at Virginia Polytechnic University and the author of the study published in the journal Science. This compound is used to make soap. The problem is that the molecular size of the plastic is huge, about 3.000 carbon atoms, while the fatty acids are much smaller.
The idea of turning plastic into soap came to Mr. Liu by accident. “It was Christmas Eve,” he said. I'm warming up by the fireplace." According to him, when wood burns, creating smoke, this smoke is created from smaller wood particles. He wondered if burning plastic would happen in a similar way.
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“Wood is mainly composed of polymers like cellulose. Burning wood breaks these polymers into short chains, then turns them into small gas molecules before fully oxidizing to carbon dioxide. If we break similar synthetic polyethylene molecules, but stop the process before they completely break down into small gas molecules, we get short-chain polyethylene-like molecules," he explains.
Mr. Liu and his colleagues have built an oven-like reactor that can be used to safely burn plastic. The bottom temperature is hot enough to break the polymer chains, while the top temperature is low enough to prevent them from breaking down too quickly.
The scientists collected the remaining compound and found short-chain polyethylene, a waxy substance. They then continue to turn this wax into soap.
“This is the first soap made from plastic in the world. It has a very unique color,” Mr. Liu said.
Mr. Liu's method was performed on polyethylene and polypropylene, the two most popular plastics today. They account for about half of all global plastic waste, which is close to 200 million tons per year. Around the world, more than 80% of plastic waste ends up in landfills, while just under 10% is recycled.
One of the advantages of the new method is that it is performed on expired plastic, which cannot be recycled by conventional means.
“Plastic pollution is a global challenge. That is one of the big problems that our society is facing. A joint effort between the research and industry communities is required. And the best way to avoid plastic pollution is to reduce plastic use,” he said.
According to VNA/Newspapers
