Evaluation of different fiber impurities on hydrothermal liquefaction of mixed textile waste

There is a need for more sustainable recycling technologies for mixed textile waste, including the two main fibers poly(ethylene terephthalate) (PET) and cotton but also containing other fiber types. Hydrothermal liquefaction has been shown to be a promising technology to recycle textile waste containing cotton and PET into bio-oil and terephthalic acid (TPA). However, the practically accumulated composition of textile waste is more complex and features more than two fibers. In the present study we investigated the effect of eight different fabrics individ-ually in ternary mixtures with a fixed ratio of cotton and PET and in a complex mixture reflecting the global fiber production. It was found that between 3 and 12 wt% bio-oil and 17-77 wt% TPA can be obtained depending on composition and temperature. Fibers with a high nitrogen content, such as suede, acrylic and nylon, significantly decreased the TPA yields due to the formation of terephthalic amides.

Automated summary

There is a need for sustainable recycling technologies for mixed textile waste, including PET and cotton, as well as other fiber types. Hydrothermal liquefaction has shown promise in recycling textile waste containing cotton and PET into bio-oil and TPA. This study investigated the effect of eight different fabrics in ternary mixtures and complex mixtures on the yields of bio-oil and TPA. The presence of high nitrogen content fibers decreased TPA yields due to the formation of terephthalic amides.