Fukui University develops fiber decolorization technology that does not require water, which is expected to promote recycling

A decolorization technology has been developed by the University of Fukui in Japan that does not generate high environmental load wastewater and therefore does not cause damage to fiber materials during the decolorization process. It is expected that the technology will also be applied to other forms of textile dyeing. Since it involves applying dyes through a previously applied decolorization process for reuse, a large amount of wasted fiber products can be reduced.

A new method for extracting color from fibers utilizes the unique properties of carbon dioxide from gas to liquid to fluid. Normally, carbon dioxide is a gas; however, under certain conditions, it can be used in the form of a supercritical fluid. By using a fluid as an operating medium, one can supply a colorant under certain thermodynamic conditions to clear the color in the fiber, restoring it to its original white state. When the gaseous carbon dioxide returns to the gas after decolorization, only the dye or decolorizing agent is separated; therefore, recycling and reuse become very convenient.

Research at the University of Fukui has confirmed that the decolorization rate of polyester fibers is close to 100%, so subsequent dyeing and use will not adversely affect the fibers. Past activities at the University of Fukui have also involved the use of similar supercritical fluids in dyeing operations. However, efforts are being made to encourage recycling in the fiber industry by making full use of existing technologies in order to achieve positive environmentally friendly recycling in this area in the coming years.