Valorizing post-consumer cotton fabrics through the extraction of cellulose nanocrystals Maria-Ximena Ruiz-Caldas, Aji P. Mathew Stockholm University, Sweden Clothing plays a crucial role in our daily lives, but the high environmental impact of clothing disposal is a growing concern as it contributes to the depletion of natural sources and waste generation. Cotton, one of the most used fibers in the textile industry, is particularly problematic as its cultivation contributes to water depletion and intensive use of pesticides and fertilizers. Additionally, the current recycling methods for cotton garments are not efficient and often result in the degradation of cotton fibers and the loss of their mechanical properties. Given this scenario, it is crucial to find alternatives for textile waste management. One way to make use of cotton textile waste is to extract cellulose nanomaterials, as cotton is more than 90% cellulose. Cellulose nanomaterials are free from the structural defects of the original cellulose fibers and can be utilized as structural elements for advanced materials. In our recent studies [12,], we have successfully extracted cellulose nanocrystals (CNCs) from cotton-based fabrics using various routes involving both mineral and organic acids. Each method allows for tailoring the CNC surface chemistry and morphology. The final product exhibited the typical characteristics of aqueous colloidal CNC suspensions and displayed a coloration that matched the dye initially attached to the cotton fabric. Notably, the presence of the dye did not affect any of the properties of the CNCs, it was simply a visual feature. All the proposed routes resulted in CNCs of high purity with structural, physical, and chemical properties comparable to those extracted from virgin sources. This indicates that dyed textiles can be easily utilized for the extraction of cellulose nanoparticles without any additional pretreatment. Additionally, the yield of CNCs from cotton-based fabrics is significantly higher compared to traditional lignocellulosic sources such as wood pulp, making it a more efficient and cost-effective method for the extraction of CNCs at an industrial scale. Not only these CNCs could potentially be used in various applications such as reinforcement in composites, templates for anisotropic materials, and scaffolds for particle growth, but the conversion of cotton fibers into CNCs can also help to mitigate the environmental impact of post-consumer textiles. References 1. Ruiz-Caldas, M.-X., Carlsson, J., Sadiktsis, I., Jaworski, A., Nilsson, U., and Mathew, A. P., Cellulose Nanocrystals from Postconsumer Cotton and Blended Fabrics: A Study on Their Properties, Chemical Composition, and Process Efficiency. ACS Sustain Chem Eng, 2022, 10, 3787–3798. 2. Ruiz-Caldas, M.-X., Apostolopoulou-Kalkavoura, V., Hellström, A.-K., Hildenbrand, J., Larsson, M., Jaworski, A., Samec,J.- S.-M., Lahtinen, P., Tammelin, T., and Mathew, A. P.,Citrated cellulose nanocrystals from post-consumer cotton textiles (submitted article)
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