Recycling of waste denim: A stepwise utilisation strategy for clean decolourisation, opening and degradation

Abstract

Denim is a relatively thick, yarn-dyed cotton fabric with a warp-faced twill weave. It is one of the most iconic types of clothing, highly popular and consumed in large quantities. The strength and colour status of discarded denim are complex and difficult to reuse, and more than 80 per cent are incinerated or disposed of in landfills. This study proposes a new strategy for recycling denim apparel with high efficiency and value-added regeneration based on the structural characteristics of denim and the state of denim after disposal: The solvent method removes the color from the fabric, and the relationship between the decolorization process, decolorization rate, and whiteness is established. Waste denim garments that meet the textile process standards are physically opened to form regenerative fibres, which are returned to the textile system, whereas fibres without spinnability are chemically degraded to microcrystalline cellulose, which has a wide range of applications and is of higher value; Decolourisation solvents can be recycled, and the recovered dyestuffs can be reupholstered for the dyeing of new cotton fabrics. This strategy allows for fully recycling all components of discarded denim garments of different qualities while avoiding the high costs and waste management problems associated with crude chemical depolymerisation.