Supercritical dyeing is a eco-friendly process. Please have a look at these useful PDF attachments.
"Yes the process is ECO-FRIENDLY."
Supercritical carbon dioxide is used for low temperature drying due to its low critical temperature. (31 degree C), environmentally friendly nature and non-flammability. In the process, wet gel samples are periodically or continuously flushed with supercritical CO2 until all solvents are removed.
Waterless dyeing exhibits environmental benefits for sustainable world. Similarly, waterless scouring, desizing and finishing bring about the same advantages for sustainable textile pre-treatment and finishing leading to more sustainable future.
The removal of solvent from a sample without passing through the liquid--gas boundary, by immersion in a supercritical fluid and de-pressurisation.
Supercritical drying (SCD) is a process by which the liquid in a substance is transformed into gas in the absence of surface tension and capillary stress and is the process most commonly used to transform gels into aerogels. Supercritical fluids based processes include extraction, impregnation, particle formation, formulation, sterilization, cleaning and chemical reactions among others. In all cases, the supercritical fluid is used as an alternative to traditional organic liquid solvents.
The most widely used supercritical fluids are CO2 (Tc = 31°C, Pc = 74 bar) and water (Tc = 374°C, Pc = 221 bar)
but some processes (extraction, reactions) involve the use of supercritical methanol, ethanol, propane, ethane mainly. Supercritical CO2 processes are the most widely spread as these are exempt of the operations of elimination of solvent residues, operations generally needed when the solvent used is an organic compound.
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