We could also dispose of your plastic waste11 Dec 2019 15:06
https://phys.org/news/2019-12-scientists-plastics-chemicals-sunlight.html
Chemists at Nanyang Technological University, Singapore (NTU Singapore) have discovered 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," said Asst Prof 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, and the leftover mass-burn ash—is transported to the Semakau landfill, which is estimated to run out of space by 2035.
Developing innovative zero-waste solutions, such as this environmentally friendly catalyst to turn waste into resources, is part of the NTU Smart Campus vision to develop a sustainable future.
Using energy from the sun to convert chemicals
The vanadium-based catalyst, which is supported by organic groups and typically abbreviated as LV(O), uses light energy to drive a chemical reaction and is known as a photocatalyst.
Photocatalysts enable chemical reactions to be powered by sunlight, unlike most reactions performed in the industry that require heat, usually generated through the burning of fossil fuels.
Other advantages of the new photocatalyst are that it is low cost, abundant, and environmentally friendly, unlike common catalysts made from expensive or toxic metals such as platinum, palladium or ruthenium.
The new vanadium-based photocatalyst developed by the NTU research team was specially designed to break these bonds, and does so by latching onto a nearby chemical group known as an alcohol group and using energy absorbed from sunlight to unravel the molecule like a zipper.