Trash to Treasure: 3D Printing of Waste-Based Polycotton Composite for The Production of Water Filters and Commodity Products

The textile industry has been proven to be one of the most polluting industries worldwide due to the extensive use of virgin resources, the vast amount of water and land used and the emergence of fast fashion which resulted to double production of garments the last 20 years. Most of these textiles end up in landfills or incineration facilities. However, the recycling of textiles is still in seminal stage due to lack of proper sorting but also due to the limitations of recycling blended fabrics and the lack of upscalable technology. Polyethylene terephthalate (PET) dominates more than 50% of the textiles market and even if there are routes to recycle it, its presence in blended fabrics mostly in combination with cotton burdens its recyclability. Most of the recycling studies investigate either the depolymerization of PET or the dissolution of cotton in order to efficiently separate them. However, in most of the cases those processes are very energy and materials intensive.<br/><br/>Here we present an upcycling route in one-pot valorization of blended cotton-PET fabrics without separating the two constituents. We performed a mild chemical treatment of cotton-PET (1:1) fragmented post-consumer fabrics during which PET was inert but the cotton was functionalized with carboxyl groups and partially fibrillated. The reaction resulted in high yields (&gt;90%) and the treated textiles were further mechanically disintegrated using a facile and short process in order to enhance their fibrillation and reduce their size. The treated textile mixture was then used for film casting which were oven-dried and cut into 1x1 cm pellets suitable for extrusion taking into account the thermoplastic nature of PET. The obtained filament was used as a feedstock for the Fused Deposition Modelling (FDM) 3D printer and several composite materials for water purification and commodity applications were printed. The presence of carboxyl groups enhanced the adsorption capacity of the polycotton filters making it possible to manufacture advanced materials from discarded garments for water purification applications. Furthermore, several fashion products with various designs were also successfully printed extending the use of the same waste feedstock in the preparation of every day polymer-based accessories.<br/><br/>The facile fabrication of customised waste-based pellets followed by extrusion and the successful 3D printing of the developed filaments into water purification filters and commodity accessories highlight the potential for upscaling and widespread commercialization. Compared to traditional 3D printing feedstocks, the waste-based filaments offer a cost-effective on-demand solution which can be widely accessible.