Deakin University develops recycling process for cotton

31 May '19

4 min read

Marking a step towards circularity, scientists at Deakin University have developed a recycling process to produce high-quality cellulose from cotton. The regenerated cellulose can be used in textile manufacturing, production of cellophane and paper, insulation and filtration, or for biomedical applications such as drug delivery and tissue engineering.

The chemical-based recycling process has been developed by the Deakin University’s Institute for Frontier Materials. The solution for recycling textiles involves dissolving cotton and regenerating it into brand-new cellulose – a complex, strong carbohydrate with many industrial uses.

With the textile industry generating so much waste, the only way to keep up with the demands set by fashion trends and the wear and tear of clothes is to make the industry sustainable. Cotton waste has traditionally been recycled through a mechanical process that produces poorer-quality recycled cotton. Only a small fraction of recycled cotton could be incorporated into new garments.

“But our recycling process dissolves the cotton waste and regenerates it as cellulose. Even cotton-blended fabrics, such as cotton-polyester blends, can be recycled in this process, so nothing goes to waste,” the university said.

This regenerated cellulose has many different possible uses. It can be spun into a textile fibre similar to native cotton or used to make aerogels – synthetic, ultralight materials comprising a network of micron-sized pores and nanoscale tunnels. The aerogels produced from this recycling process can be moulded into a structure almost identical to cartilage in the joints of the body. “We manipulate the size and distribution of tunnels to mould the aerogel within into synthetic cartilage with an ideal shape to replace damaged knee cartilage in arthritic patients,” the university said.

“While we haven’t used them in patients yet, we’ve found that the aerogels have a remarkable similarity to cartilage tissues when tested. They can replicate the type of lubrication mechanism used by cartilage in joints to protect against wear and damage,” scientists involved in the research said. “We can also shred cotton fabrics and mill them into coloured powders to dye new clothes. Since 2017, many Chinese factories that produced synthetic dyes for textiles were shut down following environmental inspections, highlighting the need for change in dyeing practices. We need new textile dyeing methods that save water, reduce pollutants, save energy and protect human health,” they added.

The new recycling process offers an environmentally friendly alternative. This process not only gives purpose to old clothing, but also eliminates much of the energy and water involved in the normal dyeing process. “We are rescuing denim and other cotton-based clothes from landfill to create cellulose fibres, aerogels and dyes from 100 per cent of the waste,” they said.

Textile waste consumes nearly 5 per cent of all landfill space, and 20 per cent of all freshwater pollution is a result of textile treatment and dyeing. Growing cotton requires harmful pesticides and fertilisers, and textile-manufacturing plants release hazardous waste into the nearby land. Synthetic dyes also come at a cost to the environment. The dyeing process involves a lot of water, and not all of it is efficiently cleaned before re-entering the environment.

Waste water from textile dyeing can affect the entire water ecosystem. This is because some dyes don’t ever degrade in water. Those that do degrade produce harmful byproducts – sometimes carcinogenic.

Importantly, despite the energy and resources used in the production process, not all cotton produced makes it into clothes. Around 23.6 million tonnes of cotton is produced each year, but the weight of stems, leaves and lint from the plant amounts to 18-65 per cent of each bale of cotton. From what is left, even more cotton fibre is lost in the process of spinning cotton buds into yarn because some fibres break during spinning. Some of this raw material waste can be used to make products such as soaps, animal feed or cotton seed oil, but the rest is thrown away. Wasted raw cotton material aside, it can take nearly 2,700 litres of water to produce a single cotton T-shirt and more than 7,600 litres to make a pair of jeans.

To counter the fast-fashion industry, circular fashion is taking off. Textile waste can now be recycled into usable products. Cotton fibres are almost purely made up of cellulose and can therefore be turned into other cellulose-based products. (SV)

Fibre2Fashion News Desk – India

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