Towards polycotton waste valorisation: depolymerisation of cotton to glucose with polyester preservation

Abstract

Every second, the equivalent of a garbage truck filled with textile waste is discarded. Due to the complex composition of clothing materials, more than 80 wt% of this waste is either incinerated or sent to landfills. Currently, only 15 wt% of textiles are recycled, and of that fraction, approximately 93 wt% undergoes downcycling, resulting in lower-value products. Generally, about 50 wt% of textile waste is composed of polycotton—a blend of cotton, a glucose-based polysaccharide, and polyester, primarily poly(ethylene terephthalate) (PET). Although this combination leverages the advantageous properties of both fibres, full valorisation of these materials is complex due to their blended structure. Simultaneously, there is an urgent need to transition away from fossil-based feedstocks. Cotton-rich textiles present a promising alternative as a non-food-based glucose source for the chemical industry, owing to their high cellulose content and widespread availability. Therefore, this review explores the current state-of-the-art methods for hydrolysing cotton into glucose through acid and/or enzymatic hydrolysis, while preserving the polyester component. These techniques enable the effective separation and subsequent valorisation of both cotton and PET fractions, facilitating their reuse in the production of new materials.