Hydrothermal liquefaction of post-consumer mixed textile waste for recovery of bio-oil and terephthalic acid

Fast fashion trends lead to significant quantities of textiles produced and discarded, its waste is incinerated or landfilled due to a lack of recycling technologies for mixed textiles. Recycling of mixed textiles by hydrothermal liquefaction (HTL) is a novel approach to produce bio-oil and monomers, as no prior sorting or color removal is required. Herein, post-consumer polyester (polyethylene terephthalate (PET)) and cotton garments were subjected to HTL to produce bio-oil and terephthalic acid (TPA). The effects of blending ratio of PET and cotton, temperature and alkali catalyst on the product distributions are investigated. A maximum bio-oil yield of 26% was attained at 325 °C for a 95% Cotton/ 5% PET mix under alkali conditions. TPA yields ranged from 48 to 91%, where 50/50% PET/cotton resulted in a higher TPA yield than 95/5% PET/cotton textile wastes. The results obtained contribute to the development of sustainable recycling processes of mixed textiles.