Plastic waste represents one of the world's largest and most challenging waste stream. Currently, less than 18% of plastic waste is recycled efficienctly with majority of the problems arising from mixed waste and contaminants. Spent lead-acid batteries on the other hand is an underused resource that usually gets neutralised into salts or diluted and discarded. This project demonstrates a novel approach to simultaneously valorise both by converting waste plastics into clean fuels and valuable chemicals using sunlight and recycled battery acid. The uniqueness of this project is the ability to tackle mixed waste streams thus offering a better approach towards plastic waste handling.

The method is suitable for polyesters, polyurethanes and polyamides. For a polyester such as polyethylene terphthalate (PET), the process begins by depolymerising PET plastic waste using sulfuric acid recovered from end-of-life lead-acid batteries. The resulting products are PET monomers: ethylene glycol and terephthalic acid which can be purified and extracted for its commercial value. Ethylene glycol can be selectively transformed into high-value products alongside hydrogen through photocatalytic reforming under solar irradiation.

This work introduces a new circular economy strategy that links two waste streams to generate sustainable energy carriers and chemical products. Beyond demonstrating a route for plastic upcycling, the research establishes a platform for solar fuel production, offering a potential pathway towards low-carbon hydrogen generation, waste remediation, and sustainable chemical manufacturing. By integrating waste valorisation, photocatalysis, and product-selective solar chemistry, this project advances the development of scalable technologies for a circular and net-zero future.