More than 8 million tons of plastic waste are dumped into the ocean per year. Plastic pollution poses a problem because the debris can survive for several hundred years. Plastic also gets into the food chain as birds and fishes ingest debris that float in the ocean and stack up in landfills.
While there are efforts that attempt to address plastic pollution such as switching plastic bags for biodegradable alternatives, mankind's reliance on plastic products call for more feasible solutions so human civilization would not drown in plastic wraps and soda bottles.
Chinese chemists appear to have come up with a potentially efficient way to address plastic pollution.
In a new study published in the journal Science Advances on Friday, Zheng Huang, from the Chinese Academy of Sciences, and colleagues reported of a new method that can break down polyethylene into usable fuel.
Polyethylene, one of the most common types of plastic used to make water bottles, food packaging, plastic film and shopping bags, is an inert substance, which means that it does not easily degrade in the environment.
Factories produce some 100 million tons of polyethylene products per year, so a scalable method of degrading it could have a significant dent in global plastic pollution.
For their study, Zhibin Guan and colleagues added an organometallic catalyst to a reaction that would degrade polyethylene at temperatures as low as 150 degrees Celsius.
The catalyst, a commercially available organic molecule, which contains the metal iridium, weakens the bond responsible for the stiff structure of polyethylene. This speeds up the process of breaking down plastic into a liquid product that can be used as diesel fuel.
"With the use of widely available, low-value, short alkanes (for example, petroleum ethers) as cross metathesis partners, different types of polyethylenes with various molecular weights undergo complete conversion into useful liquid fuels and waxes," the researchers reported.
"Common plastic wastes, such as postconsumer polyethylene bottles, bags, and films could be converted into valuable chemical feedstocks without any pretreatment."
The method uses far less energy than other similar processes because it does not involve high temperatures to break down the plastic. The method, however, is slow, taking about four days to complete, and the catalysts are expensive. The researchers, though, remain optimistic.
"We think that the future potential is there — as long as we can improve the efficiency and reduce the cost of the iridium," Huang said. "Hopefully, very soon we can scale up the process from gram scale in the lab to kilogram and even ton scale."