The article ‘Waste textile decolorization using supercritical carbon dioxide (ScCO₂) technology: design and optimization’ authored by Annah Tayebwa, Mohammad Neaz Morshed and Vincent Nierstrasz, appears in The Journal of Supercritical Fluids. The study reports on a dry, chemical-free approach to removing dyes from polyester textile waste using supercritical carbon dioxide (ScCO₂), with the aim of improving textile recycling processes.  

The research examines the effects of key process parameters including time, temperature, pressure and fabric loading on dye extraction efficiency. Using a laboratory-scale ScCO₂ system with dyed polyester (PET) fabrics and pristine PET as an absorbent, the authors found that ScCO₂ can achieve high levels of dye removal without conventional solvents or water. The work also explores a thermodynamic model (Peng-Robinson equation of state) to better understand the partitioning behaviour of dyes between ScCO₂ and polyester fibres.  

Key takeaways

• Supercritical carbon dioxide enables dry, solvent free decolourisation of polyester textile waste.  
• Optimal parameter combinations of temperature, pressure and fabric loading significantly improve dye removal efficiency.  
• The process can reach dye removal efficiencies of around 79-85 % under certain conditions.  
• ScCO₂’s high diffusivity and low viscosity help extract colourants effectively compared with traditional wet methods.  
• ScCO₂ treatment supports more sustainable recycling of coloured polyester textiles by reducing chemical and water use.  

The article highlights the potential of ScCO₂ technology as an environmentally friendlier alternative to conventional textile decolourisation processes, offering a pathway to improve polyester waste recycling and support circularity in textile value chains.  

For full details, readers are encouraged to consult the original article in The Journal of Supercritical Fluids.