Features, Latest News, News

Scientists in NSW and Vic turn waste into various recyclable plastics

Scientists at Deakin University and the University of Sydney have conducted separate research projects to find new uses for waste by turning it into plastics with various uses.

On June 14, Deakin University shared the research a team of textile and fibre scientists at the Institute for Frontier Materials conducted to turn plant waste into a biodegradable material that could replace plastics used for packaging and other throwaway items.

The team, led by Dr Maryam Naebe, developed a bioplastic by repurposing cotton gin trash – the seeds, stems, short fibres and other waste by-products left behind from the ginning process used to separate cotton fibres.

“About 29 million tonnes of cotton lint is produced each year but up to a third of that ends up as cotton gin trash, where it’s then sent to landfill or burned, representing a major environmental impact and lost material value,” Naebe said.

“Adding value to this waste product will give cotton growers and farmers an additional income stream, while also offering a sustainable alternative to harmful synthetic plastics.”

Naebe said the results were part of a project from PhD candidate Abu Naser Md Ahsanul Haque, along with Associate Research Fellow Dr Rechana Remadevi. The team has been working on transforming gin trash for more than 18 months.

The researchers dissolve the cotton leftovers using environmentally-friendly chemicals and then re-cast the recovered bio polymer into a useable bioplastic film.

The resulting material has a range of applications, such as a bale wrap, fertiliser and cotton seed packaging.

“Cotton gin trash is a promising source of renewable biomass, because when it’s broken down the resulting organic polymer can potentially be converted into a versatile biodegradable material,” Naebe said.

“Compared to synthetic plastics, our bioplastic is made without the need for toxic chemicals – which makes it safer and cheaper to produce at a mass scale – and it has the added bonus of contributing to the circular economy.”

The bioplastic can biodegrade and turn into soil, which will then in turn be used to grow cotton, resulting in cotton gin trash during the ginning process, which can then be repurposed again into bioplastic, the research indicated.

The team is now applying their process to other organic waste and fibrous plant materials such as lemongrass, hemp, almond shells, wheat straw, wood saw dust and wood shavings.

Deakin’s Institute for Frontier Materials was established to address some of the major challenges facing society through innovations in materials design and performance.

“We want to lead and inspire innovations in materials science and engineering that have a transformational impact on society,” Naebe said.

The institute’s goal is to keep pushing the boundaries of materials science in order to raise living standards across the globe – by redesigning materials for a circular economy.

Similarly, the University of Sydney has created a chemical recycling process that turns plastic waste into fuels, waxes, and new plastics that can be continuously recycled.

University of Sydney professor, Thomas Maschmeyer, led the research, which turns plastic into an asset that people would actively seek out to recycle because it can make them money.

“Of course, everyone is concerned about plastic waste, but the reality is, they also need to use plastic. Our recycling method reconciles those two ideas.”

The chemical process can also handle any kind of plastic, including the contaminated plastic that China recently stopped importing as it moves away from being the world’s largest waste recycler, according to the University of Sydney.

The recycling process is based on the catalytic hydrothermal reactor (Cat-HTR) platform, developed by Maschmeyer and his colleagues at Licella.

Using water at high pressure and high temperature, Cat-HTR breaks plastics down to their smaller chemical components. The water prevents unwanted chemical reactions, then catalysts are used to make the components rearrange themselves into new forms:

  • Solids, such as industrial waxes for the food and coatings industry;
  • Heavy liquids, such oils/greases for lubrication purposes;
  • Light liquids, such as solvents and fuels such as diesel or petrol; and
  • Reactive gases, like ethylene, which can be used to make new plastics.