SEATTLE (Scrap Monster): Monash University engineers have developed a new filtering material that could make plastic recycling cheaper, efficient and environmentally friendly by improving the recovery and reuse of valuable chemicals during processing.

The breakthrough nanocomposite membrane was developed in collaboration with CSIRO and the University of Texas at Austin. Published in the Chemical Engineering Journal, the study focuses on improving glycolysis, a chemical recycling process in which PET plastics are broken down using a liquid chemical called ethylene glycol.

PET is commonly used in drink bottles, food packaging and clothing textiles. During glycolysis, PET is converted into chemical building blocks that can be reused, but the process is made more expensive by the difficulty of recovering and reusing ethylene glycol from the reaction mixture.

Instead of relying on energy intensive separation methods, the research team developed highly selective nanocomposite membranes that act as filters to separate water from ethylene glycol.

This enables ethylene glycol to be recovered at high purity and reused in the depolymerisation process, reducing chemical waste and improving the cost effectiveness of chemical recycling.

Lead author Dr Hamidreza Mahdavi, a Research Fellow at the Monash Department of Materials Science and Engineering, said the work addresses a key gap in current recycling systems.

“Plastic waste still contains valuable building blocks. Our work shows that membrane technology can help recover these building blocks more efficiently from PET recycling streams, so they can be reused rather than wasted,” Dr Mahdavi said.

“Instead of only recovering energy from end of life plastics, we are trying to recover the building blocks needed to make new materials. This is an important step towards a more circular approach to plastic recycling.”

The study shows the membrane based separation method can operate under conditions relevant to real world recycling processes, suggesting a pathway towards future scale up.

The technology could be applied across a range of PET waste streams, including bottles, food packaging, trays and synthetic textiles.

In the longer term, the approach could help reduce plastic waste, lower emissions, improve recycling economics and support the transition to a circular economy.

The research builds on a wider program that previously reviewed advanced recycling technologies and identified membrane based systems as a promising option, followed by further work on integrating them into PET recycling.

Conducted through the CSIRO Monash collaboration project and in partnership with the University of Texas at Austin, the latest study demonstrates membrane based ethylene glycol recovery in practice, with further research planned to advance the technology.

Courtesy: www.foodmag.com.au