Raw cotton fibres (RCFs) are generally scoured and bleached to remove impurities before the dyeing process, which consumes large amounts of chemicals and water.
The process of pre-treatment is not eco-friendly as high amount of chemicals are used which in turn increase the BOD and COD of wastestream waters. Thus, researchers are trying hard to find an alternative to the conventional pre-treatment methods for sustainable processing of these cotton fibers.
A group of researchers have reported a green approach for industrial-scale dyeing involving salt-free coloration of RCFs using an eco-friendly ethanol (EtOH)–water (H2O) mixture. The article has been published in the journal Green Chemistry pulished by Royal Society of Chemistry.
The method involved initially allowing the fibers to swell in the EtOH-H2O mixture followed by dyeing in another EtOH–H2O mixture with 95% of ethanol by volume.
The results showed that the swelling solution could be reused for at least five times, and the investigated dyes exhibited superior exhaustion and total fixation levels, indicating the high rate of dye utilization and low levels of effluent discharge.
Compared with the conventional dyeing method for RCFs, this eco-friendly approach consumes fewer chemicals and energy.
Therefore, the eco-friendly dyeing of RCFs in the EtOH–H2O mixture without scouring and bleaching pretreatments is a promising approach for protecting the environment by reducing effluent discharge.
