Plastic recycling could become easier and even profitable as researchers at India’s Mandi Institute of Technology have come up with new inventions to convert the non-biodegradable product into clean energy.
Researchers have developed a method capable of transforming plastic into hydrogen when exposed to light. Generating hydrogen from plastics is particularly useful as the gas is seen as the most practical non-polluting fuel of the future. Plastics, most of which are derived from petroleum, are not biodegradable, meaning they cannot be easily broken down into harmless products.
It is said that most of the 4.9 billion tons of plastic ever produced would end up in landfills, threatening human health and the environment. Fueled by the need to prevent rampant plastic pollution, IIT Mandi researchers are developing methods that can turn plastic into useful chemicals.
The study was funded by the Program for Promoting Academic and Research Collaboration (SPARC) of the Ministry of Education. The results of this work were recently published in the Journal of Environmental Chemical Engineering. The research was led by Dr. Prem Fexil Siril, Professor and Dr. Aditi Halder, Associate Professor and co-authored by researchers, Rituporn Gogoi, Astha Singh, Vedasree Moutam, Lalita Sharma and Kajal Sharma.
Dr Prem Fexil Siril said the ideal route for effective annihilation of plastics is to degrade them into useful chemicals. Generating hydrogen from plastics is particularly useful as the gas is seen as the most practical non-polluting fuel of the future.
The IIT Mandi photocatalyst combines iron oxide in the form of nanoparticles (particles a hundred thousand times smaller than the diameter of a single strand of hair), with a conductive polymer-polypyrrole.
The researchers found that the combination of iron oxide nanoparticles with pyrrole resulted in the formation of a semiconductor-semiconductor heterojunction, which in turn resulted in strong visible light-induced photocatalytic activity. Photocatalysts generally need UV light for activation and therefore require special bulbs. IIT Mandi Catalyst can work just with sunlight.
“We first checked the photocatalytic activity of our catalyst by seeing its action on methyl orange, whose color change from orange to colorless showed how well our catalyst was able to degrade it.
We found that there was 100% degradation in four hours when they used a catalyst in which about 4% by weight iron oxide was present in the polypyrrole matrix.
While most other photocatalysts that have been developed for the generation of hydrogen from plastics release the greenhouse gas as a by-product, the IIT Mandi catalyst did not, but instead co-produced products useful chemicals such as lactic acid, formic acid and acetic acid.
Additionally, it can also be used for photoreforming food waste and other biomass, as well as breaking down pollutants in water. The interesting heterojunction properties of nano-iron oxide and polypyrrole offer the possibility of developing new catalysts for energy production and environmental applications,” he added.