Unlocking the potential of plastic recycling processes with the integration of membrane technology: a focus on PET valorisation

Plastics have revolutionised modern society; however, they have also caused environmental damage via waste accumulation. To balance their advantages with the negative impact on the environment, it is necessary to enhance recycling procedures, since the existing techniques are ineffective, require significant energy consumption, and yield recycled items of poor quality. One promising pathway is to utilise membranes. While membrane technology has been extensively studied in wastewater treatment and organic solvent recovery, its direct application to plastic recycling, particularly using real plastic feedstocks like PET, remains underexplored. This paper aims to address the gap by exploring different plastic recycling technologies, followed by an analysis of the current state of the art and then the prospective integration of membrane technology into plastic recycling processes with an emphasis on PET as a case study. This study provides a forward-looking discussion on some exciting opportunities including using conventional membrane processes and emerging membrane processes. These include separating impurities and additives from the recycling stream, recovery of valuable catalysts, and treating wastewater produced during PET recycling processes. This study also investigates emerging membrane research in PET recycling via use of mixed matrix membranes (MMMs) and implementation of hybrid membrane systems (HMSs). This study also aims to identify current challenges and future opportunities for membrane technology implementation in the field of plastic recycling, considering its impact on recycled product quality, energy consumption, and economic feasibility. Membrane technology is demonstrated to have the potential to transform the plastic recycling industry, and contribute to a more sustainable and circular economy.