Researchers at the University of Adelaide have used light-driven photocatalysis and solar energy to innovate a way to convert polyethylene waste into valuable chemicals, paving the way for sustainable waste management and contributing to the circular economy.
An international team of scientists engaged in basic research has discovered a way to use polyethylene waste (PE) as a raw material. They successfully converted it into valuable chemicals through a process called light-driven photocatalysis.
A team led by Professor Qiao Shizhang, Director of the Department of Nanotechnology at the University of Adelaide and Director of the Center for Energy and Catalytic Materials in the School of Chemical Engineering, published their research results in the journal Science Advances.
Professor Qiao said: "We use atomically dispersed metal catalysts to convert polyethylene waste plastic into ethylene and propionic acid with high selectivity. We use an oxidation-coupled room temperature photocatalytic method to convert the waste into valuable products with high selectivity. Nearly 99% of the liquid product is propionic acid, thus alleviating the problems associated with the need to separate complex products." Renewable solar energy is used instead of industrial processes that consume fossil fuels and emit greenhouse gases. This waste-to-wealth strategy consists of four main components, including plastic waste, water, sunlight and a non-toxic photocatalyst that uses solar energy to promote the reaction. The typical photocatalyst is titanium dioxide, which has isolated palladium atoms on its surface."
Most plastics used today end up being discarded and accumulating in landfills. Polyethylene is the most widely used plastic in the world. Daily food packaging, shopping bags and reagent bottles are all made of PE. Polyethylene accounts for the largest proportion of all plastic waste and is mostly found in landfills, posing a threat to the global environment and ecology.
Professor Qiao said: "Plastic waste is an untapped resource that can be recycled and processed into new plastics and other commercial products. Catalytic recycling of polyethylene waste is still in the early stages of development and is challenging in practice due to the chemical inertness of the polymer and side reactions arising from the complexity of the molecular structure of the reactants."
Currently, chemical recycling of polyethylene waste is carried out at temperatures exceeding 400 degrees Celsius, and the product composition is complex.
Ethylene is an important chemical raw material that can be further processed into various industrial and daily products, while propionic acid is also in high demand for its antiseptic and antibacterial properties.
The team's work aims to address contemporary environmental and energy challenges and contribute to the circular economy. It will be useful in further scientific research, waste management and chemical manufacturing.
Professor Qiao said: "Our basic research provides a green and sustainable solution that can both reduce plastic pollution and use waste to produce valuable chemicals, thereby achieving a circular economy. It will inspire people to rationally design high-performance photocatalysts for solar energy utilization and facilitate the development of solar-driven waste recycling technology."
Compiled from /scitechdaily