According to The Guardian (UK), plastic has similar chemical properties to fatty acids, which are one of the main ingredients of soap. Mr. Guoliang Liu - Associate Professor of Chemistry at Virginia Polytechnic University, author of the study published in Science Magazine - said that this similarity can help us convert polyethylene into fatty acids, then use this compound to produce soap. The problem is that the molecular size of plastic is very large, about 3,000 carbon atoms, while fatty acids are much smaller.
The idea of turning plastic into soap came to Mr. Liu by accident. “It was Christmas Eve. I was warming myself by the fireplace,” he said. When wood burns, it produces smoke, which he said is made up of smaller wood particles. He wondered if burning plastic worked the same way.
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“Wood is mostly made of polymers like cellulose. Burning wood breaks these polymers down into short chains, which are then converted into small gas molecules before being completely oxidized to carbon dioxide. If you break down similar synthetic polyethylene molecules, but stop the process before they are completely broken down into small gas molecules, you get molecules that look like short-chain polyethylene,” he explains.
Liu and his colleagues have created an oven-like reactor that can be used to safely burn plastics. The temperature at the bottom is hot enough to break down the polymer chains, while the temperature at the top is low enough to prevent them from decomposing too quickly.
Scientists collected the remaining compound and found short-chain polyethylene, a type of wax. They then went on to turn this wax into soap.
“This is the first soap made from plastic in the world. It has a very unique color,” said Mr. Liu.
Liu’s method works on polyethylene and polypropylene, the two most common types of plastic today. Together, they account for about half of all global plastic waste, nearly 200 million tons per year. Worldwide, more than 80% of plastic waste ends up in landfills, while less than 10% is recycled.
One of the advantages of the new method is that it can be performed on end-of-life plastics, which cannot be recycled in conventional ways.
“Plastic pollution is a global challenge. It is one of the major problems facing our society. A joint effort is needed from the research and industrial communities. And the best way to avoid plastic pollution is to reduce plastic use,” he said.
According to VNA/Tin Tuc Newspaper
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