The textile industry, responsible for approximately 60% of discarded clothing, faces a pressing environmental challenge. Its heavy reliance on toxic chemicals during dyeing and processing makes it the world’s second most environmentally damaging industry. A sustainable solution is urgently needed to reduce the environmental burden of textile waste.
Researchers at the University of Fukui, Japan, have developed a promising answer: a revolutionary dye extraction process utilizing supercritical carbon dioxide. This innovative technique, known as supercritical fluid dyeing, allows for the complete removal of dyes from fabric, specifically polyester fibers, which dominate the textile market. The extracted dyes can then be reused, and the decolorized fabric can be re-dyed, creating a truly circular system.
Led by Professor Kazumasa Hirogaki and Visiting Professor Teruo Hori, the research team has successfully optimized the decolorization process, ensuring minimal environmental impact. The process involves creating a supercritical carbon dioxide fluid in a specialized pressurized vessel and then mixing it with a decolorizing agent before introducing it to the dyed fabric.
The researchers explored three distinct decolorization methods, each tailored to specific textile, dye, and decolorizing agent characteristics:
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Solvent Trapping:
Supercritical carbon dioxide dissolves the dye and traps it in a solvent phase at the bottom of the vessel.*
Solid Trapping:
The processing body is re-treated with a decolorizing agent, or an adsorbent is placed in the vessel. The supercritical fluid extracts the dye and traps it onto the processing body or adsorbent.*
Homogenous Method:
The decolorizing agent is dissolved in the supercritical fluid, and the extracted dye also dissolves in the supercritical fluid.These methods have achieved remarkable decolorization rates exceeding 90-100%, particularly for polyester fabrics. Furthermore, the processing liquids, extracted dyes, and decolorizing agents can be effectively repurposed and reused, further minimizing environmental impact.
The team at the University of Fukui is actively seeking to commercialize this technology, aiming to transform the textile industry’s traditional linear model of ‘make, use, and dispose’ into a sustainable ‘make, use, and reuse’ circular system. This groundbreaking approach holds immense potential to mitigate the environmental impact of textiles and pave the way for a more sustainable future for fashion.