NTU SPMS Assistant Professor Soo Han Sen with the plastic-photocatalyst mixture, which when exposed to sunlight converts plastic to formic acid.
Chemists at Nanyang Technological University, Singapore (NTU Singapore) discover a method that could turn plastic waste into valuable chemicals by using sunlight. In lab experiments, the research team mixed plastics with their catalyst in a solvent, which allows the solution to harness light energy and convert the dissolved plastics into formic acid – a chemical used in fuel cells to produce electricity.
Reporting their work in Advanced Science, the team led by NTU Assistant Professor Soo Han Sen from the School of Physical and Mathematical Sciences made their catalyst from the affordable, biocompatible metal vanadium, commonly used in steel alloys for vehicles and aluminum alloys for aircraft. When the vanadium-based catalyst was dissolved in a solution containing a non-biodegradable consumer plastic like polyethylene and exposed to artificial sunlight, it broke down the carbon-carbon bonds within the plastic in six days. This process turned the polyethylene into formic acid, a naturally occurring preservative and antibacterial agent, which can also be used for energy generation by power plants and in hydrogen fuel cell vehicles.
“We aimed to develop sustainable and cost-effective methods to harness sunlight to manufacture fuels and other chemical products,” says Soo. “This new chemical treatment is the first reported process that can completely break down a non-biodegradable plastic such as polyethylene using visible light and a catalyst that does not contain heavy metals.”
In Singapore, most plastic waste is incinerated, producing greenhouse gases such as carbon dioxide. The leftover mass - burn ash - is transported to the Semakau landfill, which is estimated to run out of space by 2035.
For more information, visit: www.ntu.edu.sg
