New method can treat all conventional plastics
(sustainabilityenvironment.com) – How to recycle plastic without using high temperatures or large amounts of energy but obtaining a high value end product? Answering this question has been difficult for a long time. Mechanical recycling leads to products with performance far removed from virgin plastic, while the chemical one through pyrolysis – the most common solution on a commercial level – is an energy-intensive process. Obviously, the options are not limited here, but a group of scientists from Nanyang Technological University of Singapore (NTU Singapore) has announced that they have created a photocatalytic process for the upcycling of non-biodegradable low energy plastics.
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Developed by associate professor Soo Han Sen, the new method uses LED light to activate and break inert carbon-carbon bonds in plastic polymers, with the help of a vanadium photocatalyst. “Our innovation not only provides a potential response to the growing problem of plastic waste but also reuses carbon trapped in these plastics instead of releasing it into the atmosphere as a greenhouse gas through incineration,” Soo explains. The end products of the process are chemical ingredients such as formic acid and benzoic acid, which can be used to synthesize other chemicals used in fuel cells and liquid organic hydrogen (LOHC) vectors.
How to recycle plastic with LEDs
The process to recycle plastic with LEDs was illustrated in the scientific publication “Upcycling of non-biodegradable plastics by metal-based photocatalysis” in the journal Chem. First, plastic waste is dissolved in an organic solvent (dichloromethane) to make their polymer chains more accessible to the photocatalyst. The solution is then mixed with vanadium and slid through a series of transparent tubes on which the light of two 12 V/50 W white LEDs is reflected.
Lighting provides the initial energy to break C-C bonds in a two-step process that releases easily isolatable formic acid and benzoic acid. The technology, scientists explain, could also use sunlight and allows to treat a large number of conventional plastics such as polystyrene, polypropylene, polyethylene, polyvinyl chloride and polyvinyl acetate. The NTU team has filed a patent for their photocatalytic process, which is designed with industrial scalability in mind, through the innovation and enterprise company of NTUitive University. Scientists are now looking for partners to market the technology.