Recoloring polyester with supercritical CO₂ could simplify fiber-to-fiber recycling

Colored polyester is difficult to recycle because the dyes are hard to remove without using large quantities of chemicals, water or energy. Researchers have developed a supercritical carbon dioxide treatment that redistributes existing dyes between polyester fibers, creating uniform colors without removing the original dyes. By controlling fiber proportions, they tuned shades and developed a model that accurately predicted color strength.