Processing of dyed cotton-based waste garments for re-use through the lyocell processing technology

The world’s population growth together with the change in lifestyle and fashion culture has led to an increased demand for textile fibres. Fuelling this growth is the increasing number of short fashion seasons in the clothing retail markets, which has led to the overall decreased lifespans of clothing in developed countries such as the United Kingdom, which in turn has resulted in a significant increase in waste textile. The current disposal routes for the generated waste textile is through reuse or recycling, with up to 30% of the waste being landfilled or incinerated. Both landfill and incineration of waste textile are associated with environmental pollution, while reuse of waste garment as second-hand clothing is associated with the decline of the textile industries in developing countries due to the lower cost of the imported second-hand garments undercutting the local products. Moreover the common mechanical recycling of the waste textile back to the component fibre is also compromised by the presence of colour and mixed fibre blends which in turn results in low value non-woven products. This study investigated the potential methods to chemically recycle waste cotton garments and reuse the recycled materials as feedstock for producing regenerated cellulosic fibres through the Lyocell process. Methods to chemically ‘strip’ colorants and finishing agents from waste cotton garments were first established and their efficiency evaluated. Acid and alkali hydrolysis, dithionite reduction and oxidative bleaching were evaluated as potential methods for delivering cheap, efficient and environmental-friendly colour removal from cotton substrates. It was established that, the sequential acid/dithionite/peroxide treatment could strip a wide range of colorants from cotton fabrics, while the sequential acid/alkali/peroxide treatment could only strip relatively few colorants from the cotton substrates. The recycled waste cotton garments were successfully used to generate Lyocell fibres from both 100% recycled cotton pulp and a blend of recycled cotton pulp (20%) and wood pulp (80%). Both the fibre’s mechanical and structural properties were assessed using tensile parameters, X-ray diffraction spectroscopy (XRD), Fourier Transform Infrared (FTIR) and scanning electron microscopy (SEM) and were compared to the conventional Lyocell fibres from wood pulp. The overall findings of this study demonstrated the potential of reusing waste cotton garments through the Lyocell process and producing fibres with properties similar to conventional Lyocell fibres.