Most textile waste is either incinerated or landfilled today, yet, the material could instead be recycled through chemical recycling to new high-quality textiles. The focus of this paper is on the separation of cotton and PET from mixed textiles, called polycotton.
The study involved a lab-scale evaluation of PET hydrolysis using NaOH at specific concentrations and temperatures. In the process, the PET was degraded to terephthalic acid (TPA) and ethylene glycol (EG). Three product streams (cotton, TPA, EG, and other process chemicals) were generated. The end products and the extent of PET degradation were characterized using light microscopy, UV-spectroscopy, and ATR FT-IR spectroscopy, solution and solid-state NMR spectroscopy, and an intrinsic viscosity of cotton cellulose.
The findings show that with the addition of a phase transfer catalyst, PET hydrolysis (at specific conditions) can be completed within 40 min. The yield of the cotton cellulose was high, up to 97%, depending on how long the samples were treated. The findings also showed that the separation can be performed without the phase transfer catalyst; however, this requires longer treatment times, which results in more cellulose degradation.
Read More: Development of an efficient route for combined recycling of PET and cotton from mixed fabrics