Countries worldwide are battling to reduce mountains of plastic waste AFP/Prakash SINGH
Scientists said Wednesday (Dec 12) they have come up with an environmentally-friendly method that uses artificial sunlight to transform plastic into power-generating chemicals, as countries worldwide battle to reduce waste.
Huge quantities of plastic have piled up on land and been dumped in the sea across the world, with Asian nations in particular facing criticism for failing to tackle the problem.
Researchers in Singapore say they have converted plastic into "formic acid", which can be used in power plants to generate electricity, by using a catalyst which neither damages the environment nor costs a lot of money.
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NTU scientists devise method to turn plastic waste into valuable chemicals using sunlight
Scientists at Nanyang Technological University (NTU) have devised a way to turn non-biodegradable plastic waste into valuable chemicals using sunlight.
The technique uses a low-toxicity “catalyst” to dissolve the plastic molecules through exposure to sunlight, said Assistant Professor Soo Han Sen, who led a team of five scientists on the project.
At a press conference on Wednesday (Dec 11), Asst Prof Soo said the process resulted in formic acid – a highly versatile natural chemical that can be used as a food preservative, antibacterial cleaning agent or in fuel cells for hydrogen energy.
related: Packaging waste is everywhere, including in your body
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NTU Singapore scientists convert plastics into useful chemicals 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.
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Sunlight turns plastic waste into key element of hydrogen fuel cells
Could plastic waste one day provide a key ingredient for zero-emission transport?
The key to the breakthrough was the introduction of a new kind of photocatalyst, which is a material that harnesses light energy to power chemical reactions. In search of new ways to convert plastic waste into useful chemicals, the NTU team turned to a type of affordable, biocompatible metal called vanadium. This commonly forms part of the steel and aluminum alloys used in cars and aircraft, but the scientists found it might play a role in plastics recycling, too.
By adding the vanadium-based catalyst to a solution containing consumer plastics, heating it to 85° C (185° F) and then exposing it all to artificial sunlight, the team was able to break down key bonds within the plastic in the space of six days. Breaking apart these carbon-carbon bonds typically involves high temperatures, which is energy-intensive, but by harnessing sunlight instead the scientists may have found a greener way forward.
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Scientists convert plastics into useful chemicals using sunlight
Most plastics are non-biodegradable because they contain extraordinarily inert chemical bonds called carbon-carbon bonds, which are not readily broken down without the application of high temperatures.
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.
As the experiments were conducted at laboratory scale, the plastic samples were first dissolved by heating to 85 degrees Celsius in a solvent, before the catalyst, which is in powder form, was dissolved. The solution was then exposed to artificial sunlight for a few days. Using this approach the team showed that their photocatalyst was able to break down the carbon-carbon bonds in over 30 different compounds and the results demonstrated the concept of an environmentally-friendly, low-cost photocatalyst. The research team is now pursuing improvements to the process that may allow the breakdown of plastics to produce other useful chemical fuels, such as hydrogen gas.
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Scientists to harness the sun to transform plastic into power-generating chemicals
In lab experiments, researchers from the city's Nanyang Technological University mixed plastic with chemicals to form a solution, which could then be broken down by artificial sunlight.
The plastic was broken down in six days, and scientists hope the process can be carried out in future under real sunlight.
"We are able to turn plastics, which are of course polluting the oceans, into useful chemicals," said Soo Han Sen, who led the two-year research project and is from NTU's.
related:
What to do with all the plastic trash?
Phasing out plastic: what is the alternative?
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Waste to bioenergy: a review on the recent conversion technologies
Scientific studies have demonstrated that it is possible to generate a wide variety of bioenergy from biomass residues and waste, and however its cost is not competitive with petro-fuels and other renewable energy. On-going efforts are continued extensively to improve conversion technologies in order to reduce production costs.
The present review focuses on the conversion technologies for transforming biomass residues and waste to biofuels, specifically their technological concepts, options and prospects for implementation are addressed. The emerging developments in the two primary conversion pathways, namely the thermochemical (i.e. gasification, liquefaction, and pyrolysis) and biochemical (i.e. anaerobic digestion, alcoholic fermentation and photobiological hydrogen production) conversion techniques, are evaluated.
Additionally, transesterification, which appears to be the simplest and most economical route to produce biodiesel in large quantity, is discussed. Lastly, the strategies for direct conversion of biomass residues and waste to bioelectricity including the use of combustion and microbial fuel cells are reviewed.
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Tiny particles help plastic break down in the sun
Tossing a plastic bag out of a car window isn’t just rude. It creates a huge problem. That’s because when plastic enters the environment, it can take years — if not a century — to go away. Worse, this litter can break down into microplastics, tiny particles that can move into rivers and oceans, where animals may mistake them for food. But Thomas Colburn, 17, has come up with a new recipe for plastic. This plastic breaks down into harmless carbon and gas. All it needs to do this is a bit of sunlight.
Thomas, a senior at Oak Ridge High School in Tennessee, is on his school’s cross-country team. He loves to run for miles along trails that surround his town. But he hated seeing plastic trash as he ran — trash that he would spot over and over again.
At the Governor’s Schools for the Sciences and Engineering, a summer program in nearby Knoxville, Thomas had the chance to create plastic polymers. These molecules are long chains of repeating groups of atoms, commonly used to make plastic. They can be found in everything from shopping bags to cell phone cases and even socks. As Thomas made the polymers, the teen began to think about ways to un-make them. What he learned might suggest ways to get rid of the plastic that litters his running paths.
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New filter uses sunlight to break down ocean-bound plastics
A microscope image of the semiconductor-coated wires used in the KTH team's new microplastic filter
Plastic's resilience makes it great for product packaging, but not so great when it ends up in the ocean. Now, scientists from KTH Royal Institute of Technology in Sweden are testing a new filter system to catch tiny bits of plastic before they enter natural waterways, and quickly break them down using visible light from the Sun.
The silky smooth texture of some toothpaste or hand soaps owes a lot to plastic microbeads, and while these additives are currently being phased out, microplastics are still getting into our waterways. They've penetrated even the deepest trenches of the oceans, where they not only pollute the environment but are eaten by marine animals and slowly poison creatures all the way up the food chain.
"These plastics will start accumulating in the food chain, transferring from species to species, with direct adverse consequences to human population," says Joydeep Dutta, chair of the Functional Materials division of KTH. "Tackling plastic pollution at its source is the most effective way to reduce marine litter." Normally, plastics break down with exposure to sunlight in a process called photocatalytic oxidation, but that can take many years. So the KTH team, along with a Swedish company called PP Polymer AB, developed a membrane that speeds it up.
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The sun can help break down ocean plastic, but there’s a catch
As of 2014, 5 trillion plastic pieces are floating around the planet's oceans
With the help of sunlight, plastics in the ocean dissolve into carbon that some microbes will turn into food. What if the plastic in the ocean could burn itself up? This thought might not be too far from the truth. A recent study in the Journal of Hazardous Materials found that when four different types of post-consumer microplastics collected from the waters of the North Pacific Gyre were placed under a solar simulator, they dissolved into organic carbon.
Currently, scientists predict that 5 trillion plastic items, most of which are teensy microplastics, are currently floating around in the world’s oceans, weighing over 250,000 tons. Still, researchers have estimated that the plastic found at the surface of the sea is only around one percent of the plastic that has gone into the oceans.
However, the plastics on the surface are unique in that they are exposed to sunlight. And, since plastics are made of polymers of carbon, that sunlight breaks down larger plastics into carbon over time, says Aron Stubbins, an author of the study and professor of marine sciences and engineering at Northeastern University.
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related:
Packaging waste is everywhere
Harnessing the sun to turn plastics into useful chemicals
40-yr-old KFC plastic bag found
We're Eating a Whole Lot of Plastic
Microplastics in Your Bottled Water
Is this the end of recycling?
Plastic waste to return to Sender
Plastic waste is a threat to wildlife
Why is plastic a problem?
Harnessing the sun to turn plastics into useful chemicals
40-yr-old KFC plastic bag found
We're Eating a Whole Lot of Plastic
Microplastics in Your Bottled Water
Is this the end of recycling?
Plastic waste to return to Sender
Plastic waste is a threat to wildlife
Why is plastic a problem?
