Japanese researchers successfully decompose polyethylene plastic at lower temperatures
Xinhua News Agency, Tokyo, July 10 (reporter Qian Zheng) Decomposition polyethylene, polypropylene and other plastic materials usually need more than 300 degrees Celsius high temperature conditions, more energy consumption. Japan's University of Tokyo recently released a news bulletin said that researchers at the school under the catalysis of cerium, the use of visible light irradiation containing a small amount of carboxyl polyethylene, successfully achieved a low temperature environment of 80 degrees Celsius ordered the decomposition of this polyethylene.
Communique said that environmental pollution caused by plastic waste has increasingly become a serious social problem, especially the recycling of plastic materials such as polyethylene and polypropylene in large production volumes is an urgent problem to be solved. However, the carbon-carbon bonds contained in the molecular chains of polyethylene and polypropylene are very stable, so that their decomposition generally requires high temperature conditions of more than 300 degrees Celsius.
The production of carbon free radicals is the key to triggering the break of carbon-carbon bonds. The University of Tokyo research team introduced a small number of carboxyl functional groups into polyethylene, and then for this carboxylated polyethylene powder, explore the reaction conditions that can make carboxyl groups produce carbon free radicals under light irradiation.
The study found that in the 80 degree Celsius acetonitrile with a small amount of cerium catalyst, the carboxylated polyethylene powder can be irradiated with a LED lamp with a luminous wavelength of 430 nm to generate carbon free radicals, and its high reactivity cuts off the carbon-carbon bond on the polyethylene molecular chain, and the long chain carboxylated polyethylene molecules are degraded into fragments with molecular weight of about 500. The study also confirmed that this reaction can be carried out not only in acetonitrile, but also in water.
The related paper was recently published in the Journal of the American Chemical Society. The bulletin said that this study achieved the decomposition of polyethylene in a lower temperature environment, which usually requires high temperature conditions, indicating that polyethylene modified by carboxyl functional groups is expected to be used as degradable plastics in the future, which will make recycling more energy efficient and low cost.