Supercritical CO2 technique offers route to recycle coloured polyester

Researchers at the University of Fukui in Japan have developed a novel processing method using supercritical carbon dioxide ($scCO_2$) to recycle coloured polyester fabrics without requiring prior dye removal. The technique allows post-consumer synthetic fibres to be re-dyed into new shades directly during processing, addressing one of the primary technological bottlenecks in synthetic textile and polymer circularity.

Traditionally, recycling mixed-colour polyester waste into high-value applications presents severe technical challenges. Stripping existing dyes often requires energy-intensive chemical treatments, high water consumption, or hazardous solvents. Consequently, substantial volumes of coloured synthetic scrap are downcycled into low-grade applications or sent to disposal. By employing $scCO_2$ as a dye medium, the researchers demonstrated that dyes can be redistributed or overlaid effectively, bypassing the resource-heavy decolouration stage.

Why it matters

Synthetic textiles and Polyethylene Terephthalate (PET) packaging share core chemical structures. As UK and European regulatory frameworks push for stricter circular economy targets and higher recycled content across consumer goods, recyclers face increasing pressure to handle complex, coloured waste streams. Technologies that eliminate water-intensive washing or chemical stripping steps offer a dual benefit: lower operational energy demands and significantly reduced liquid effluent treatment burdens.

What it means for recyclers and processors

For waste management companies, polymer processors, and recyclers operating across the UK and Türkiye, this development underlines the potential of solvent-assisted processing in modern recycling. Türkiye represents a major regional hub for synthetic fibre processing and textile recycling, linked closely with UK consumer markets and circular economy supply chains.

While $scCO_2$ processing requires specialised high-pressure equipment, eliminating water usage and chemical stripping aligns directly with Scope 1 and Scope 2 carbon reduction targets. As corporate sustainability reporting and ESG audits become mandatory across European supply chains, integrating waterless re-processing technologies will increasingly influence corporate compliance and carbon accounting metrics.

Practical takeaway

Recyclers and reprocessors managing PET and synthetic fibre waste should track commercial scale-up trials of supercritical fluid technology. Operating facilities planning future equipment upgrades ought to evaluate how waterless processing can mitigate rising trade effluent costs and improve life-cycle carbon figures.

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Reported by Recycling Today — original article