The effect of dyeing and finishing in textile recycling
Chemical recovery is an important step to realize closed - loop textile supply chain. However, chemical recycling also carries the risk of retaining or spreading hazardous substances found in dyes, softeners, anti-wrinkle agents and other common additives. A new study investigated decolorization and regeneration of cotton into viscose fibers to analyze potentially dangerous textile finishing components during the whole process.
Decolorization and decolorization of finishing agents and reactive dyes
In this study, a new continuous alkali/acid pretreatment bleaching process was used to peel off the finish and reactive dye, and the regeneration performance of viscose fiber was evaluated. From a sustainability point of view, the chosen bleaching sequence can be integrated into the viscose process, thereby reducing cost and environmental impact. This has previously been done on crease-free fabrics, but not on fabrics that are both crease-resistant and dyed. The resulting viscose fibers were tested for technical properties, i.e. mechanical properties such as fracture toughness and elongation, as indicators of spinning results.
The results show that the decolorization method used has the potential to remove the types of reactive dyes, wrinkle-free agents and softeners tested in this study. However, the adaptability of decolorization process to cotton substrate needs further tests. In view of the dirt and water repellent in cotton flow, the author suggests designing another decolorization method.
Global demand for cellulose-based fibers
As the global demand for textile fibres is expected to increase, there will be a significant gap between the demand for fiberwikis and the available supply. This gap can be reduced to some extent by using post-production and post-consumption cotton as a raw material for recycled man-made fibres, such as viscose or Lyocell. As a result, some participants seek to recycle cotton fabrics and chemically recycle recycled cotton fibers into other types of textile fibers.
An important processing aspect of chemical recovery is the ability to produce pulp with a low impurity content. Most cotton fabrics contain colorants and finishes that can be considered impurities during chemical recovery. Removing these impurities at decolorization stage will improve the solubility of fibers and stabilize and simplify the fiber regeneration process.