Recent advances in supercritical fluid dyeing

Abstract

Supercritical fluid dyeing is a promising technology that was first proposed in the 1980s to overcome the high energy demand and water consumption of conventional textile coloration. This review covers its advances from 2014 to the present, from the successful industrial implementation of supercritical fluid dyeing of polyethylene terephthalate to the most recent results obtained for the dyeing of other synthetic and natural textiles. Specific attention is also dedicated to the most innovative applications of supercritical fluid dyeing such as the functionalisation of textile and non-textile substrates, which may give rise to the development of other sustainable processes or novel advanced materials in the near future.

A fungal‐based anthraquinone emodin for polylactide and polyethylene terephthalate in supercritical carbon dioxide (SC‐CO2) dyeing

“…A possible explanation for the limited usage lies in the high price of the final product, due to expensive machinery needed for the process, which does not accommodate consumer expectations regarding inexpensive clothing. This has probably prevented wider support of fashion brands for SC‐CO 2 and other waterless techniques 12 . However, the greater need of sustainability in textile producing processes will increase the pressure to adopt alternatives for water in textile operations.…”

“…SC‐CO 2 dyeing provides shorter dyeing periods as well as usage of less energy and chemicals when compared to conventional water dyeing processes, and therefore lower process costs 10 . SC‐CO 2 dyeing can even be carried out without any additional process chemicals, for example dispersing agents, and CO 2 medium can be recycled in a closed loop process 11‐13 . An acceptable ratio for the recycling efficiency of CO 2 has been reported ranging from 92% to 95% 11 .…”

“…SC‐CO 2 exhibits densities and solvating powers similar to those of liquid solvents yet has extremely rapid diffusion characteristics and viscosity similar to those of a gas 6 . In the supercritical stage carbon dioxide has a very high solvent power, allowing the dye to dissolve easily and, because of the high permeability, dyes are transported easily and deeply into fibers, creating bright colours with good colour fastness properties 12 . In addition to dyeing, scouring, desizing and different finishing applications take the advantage of SC‐CO 2 technology 10,12 …”

Solute Diffusion into Polymer Swollen by Supercritical CO2 by High-Pressure Electron Paramagnetic Resonance Spectroscopy and Chromatography

“…Since pioneering reports by Berens [ 1 ] and Sand [ 2 ], the impregnation of polymers using supercritical fluids (SCFs) has remained of great interest in many applications, such as the loading of biocompatible materials with drugs [ 3 , 4 , 5 ] and food packaging materials with antioxidants, antimicrobials, etc. [ 6 , 7 ]; supercritical polymer dyeing [ 8 , 9 , 10 , 11 , 12 , 13 ]; fabrication of nanocomposites [ 14 , 15 , 16 , 17 ]; and polymer blends [ 18 , 19 , 20 ], just to name a few. SCFs make these approaches to polymer modification efficient and environmentally friendly.…”

“…For technological applications, it is important to predict the amount of an impregnated substance and its distribution in a polymer. Therefore, a solute diffusion rate in the Polymers 2021, 13, 3059 2 of 16 swollen polymer matrix and its distribution coefficient between the SCF medium and the polymer are needed for this to be known. Under normal conditions, the diffusion rate of a solute in a medium such as solvent-swollen polymers or porous materials soaked with a solvent is measured using different methods, such as the diffusion (diaphragm) cell and infinite cylinder/semi-infinite slab methods (with either uptake measurement or sectioning/imaging to obtain the concentration profile) [25], electrochemical methods [26], NMR methods (Pulsed Field Gradient NMR, NMR imaging, etc.)…”