Colored Silk Fibroin from Silk Waste for New Fabric Dyeing

Waste recycling is a crucial issue, directly linked to the urgent need to cut carbon emissions and support sustainable development. In this work, we reclaimed colored silk fibroin (CSF) from colored waste fabrics as a naturally amphiphilic, protein-based dye system for coloring wool, silk, nylon, and spandex fabrics. The CSF-dye showed better diffusion and infiltration than the conventional dye solution. This is due to the amphiphilic nature of silk fibroin, which behaves like a surfactant, facilitating dyeing. The CSF-dye performed better on wool and silk than on nylon and spandex. The former exhibited a high dye uptake of over 95% and good washing and rubbing fastness (≥4). Under optimal conditions, 1 kg of waste can be recycled to dye 3.2 kg of new fabrics. The versatility of this dye system was also demonstrated in making a new color by simply mixing two existing colors at specific ratios. The findings in this study offer an alternative strategy for recovering and reusing color from waste fabrics.