An overview of cotton and polyester, and their blended waste textile valorisation to value-added products: A circular economy approach – research trends, opportunities and challenges

Fast-changing fashion trends have resulted in increases in textile production and waste generation. The environmental impacts of the production, consumption and end-of-life of textiles are amply documented. Therefore, the industry has started to shift from the linear economy principle of 'take-make-waste' to the circular economy concept, where textiles can reenter the life cycle rather than being wasted and thus form a closed loop, resulting in resource savings and reduced environmental impacts. To this end, valorization of solid waste streams from the textile industry to recover fibers and marketable value-added products has gained increasing attention in recent years. Textile waste valorization involves three main steps: pretreatment, enzymatic hydrolysis and fiber regeneration. This review presents the main methodologies and the most recent technical developments in these valorization strategies, the value-added products obtained and their applications. Furthermore, the review describes fermentative products synthesized using cellulosic glucose from the cotton fraction of waste streams. Gaps and challenges in existing strategies are identified for potential future research. This review will help to apprize researchers and practitioners of important recent developments in effective textile valorization via upcycling and guide them in the design of efficient strategies for sustainable management of textile waste streams.