Colored silk fibroin reclaimed from dyed silk and its utilization in wool dyeing

This work reports a novel approach to color wool with regenerated silk fibroin (RSF) reclaimed from dyed silk waste. The color retention results showed that the original color in the dyed silk waste with either acid dye or reactive dye was retained with >90 % efficiency in the RSF. Furthermore, the reclaimed colored silk fibroin (CSF) was utilized in wool dyeing. Due to the dissociation of non-covalent bonds, acid-dyed CSF demonstrated 70 % higher than the reactive-dyed CSF in the reuse of color in CSF. Wool dyed with the acid-dyed CSF at 75 °C demonstrated higher color strength and better dye penetration than that dyed with traditional dye, typically carried out at 95 °C, because silk fibroin enhanced the surface wettability of wool and thus facilitated liquid infiltration. Importantly, this recycling method can be readily applied to discarded commercial silk fabrics. This study has the potential to valorize silk waste and contribute to fashion sustainability.