Textile Recycling Technologies, Colouring and Finishing Methods

3.3.2.2 Chemical Recycling 
The chemical recycling process of cotton is based on the dissolution of cellulose. Two main routes 
which have been explored include: the depolymerization of glucose monomers for use in other 
applications, or a polymer dissolution route where the separation and regeneration of cellulosic 
fibres occurs by use of solvents.
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 The latter process may recover a chemically modified or pure 
cellulosic fibre products, which can also be incorporated as feedstock for regenerated/recycled 
man-made cellulosic fibres (MMCs).
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Chemical processes for recycling and regenerating 
MMCs would also reduce the burden of toxic chemicals, namely carbon disulfide used in 
conventional viscose production, and enable the production of fibres with equivalent virgin 
quality.
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The Lyocell (NMMO) and Ionic Liquid processes are two main chemical recycling 
methods which have been explored and developed. Figure 17 summarizes the different chemical-
based processes for cotton fibre recycling.
 
Figure 17: Overview of cotton chemical recovery processes. 
Reproduced and modified from [8].

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The Lyocell method (Figure 18) can be applied to 100% cotton fabrics for regeneration of cellulosic fibres (MMCs) using N-
methylmorpholine N-oxide (NNMO) to dissolve cotton fibres (dissolving pulp). The regenerated fibres are produced by processing the 
dissolved pulp (cotton waste) and blending with other plant-derived pulp products (wood, flax, hemp, etc.). 
Figure 18: Overview of Lyocell process.
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Reproduced and modified from [88]. 
 

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The ionic liquid process (Figure 19) can be applied to blended cotton fabrics. Researchers from Aalto University and the University of 
Helsinki who developed the Ioncell-F process, applied the ionic liquid solvent, [DBNH]OAc (1,5,diazabicyclo[4.3.0]non‐5‐enium 
acetate) to chemically recycle cotton waste and produce MMCs, with the fibres exceeding tensile strength of native cotton and 
commercial MMC fibres.
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Researchers from Deakin University demonstrated the use of ionic liquid, 1 allyl-3-methylimidazolium 
chloride (AMIMCI), to separate cotton from polyester blend (50:50 polycotton blend). While still in developmental phase, it has 
potential to produce 100% recycled cotton product, but may also be blended with other pulp product to produce regenerated cellulosic 
materials.
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Figure 19: Overview of ionic liquid process. 
Reproduced and modified from [88].

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