Scientists Develop New Efficient Method To Recycle Plastic Waste Into Liquid Fuel

In a major breakthrough, scientists have developed a new method to turn polyethylene, the most common form of plastic used in making grocery bags and bottles, into a liquid fuel.

The problem with plastics is that they don't degrade quickly into biologically compatible products. In fact, according to a recent survey, it's estimated that the oceans will have more plastic than fish by 2050.

Current methods of converting plastic into liquid fuel require the material to be exposed to intense heat or ultraviolet radiation. The end byproducts of such recycling methods are often as hard to degrade as polyethylene itself. What's great about the new plastic recycling method, described in the journal Science Advances, is that it uses less energy as compared to other methods and produces a higher quality end product.

Zheng Huang, an organic chemist at the Chinese Academy of Sciences, and his team has come up with a new plastic recycling method that allows the degradation process to be carried out at very low temperatures and with much more control.

According to the research team, the process they have developed, known as cross alkane metathesis (CAM), is extremely efficient in breaking down the plastic without any pretreatment. The process uses chemical catalysts that are normally used to produce polymers, and sets them to breaking down polymers instead. The first catalyst breaks apart the hydrogen atoms from the carbon atoms, which causes the carbon atoms to form bonds with each other.

The second catalyst then breaks down the newly bonded carbon atoms form double, rather than single, bonds. The separated hydrogen atoms are infused back into the mixture and the process is repeated a number of times after which the structure of the polyethylene gradually changes into either a diesel fuel or a wax that can be used for industrial purposes.

The recycling process involves heating at around 175 degrees Celsius (347 fahrenheit) to break down the plastic. The only drawback of the new recycling method is that the process is slow and takes about four days to complete and that the catalysts are a bit expensive to use.

The new research is part of a four-year research project by a team of scientists from the University of Shanghai and the University of California, Irvine.