Pilot-scale Study: Hydrolyzed Reactive Dye Removal Using Direct Ozone Injection in Jet Dyeing Machine

摘要

This pilot-scale study investigated a newly developed and patented wash-off method to clear unfixed reactive dyes from cotton knit fabrics. The new method appeared to be a promising alternative to the conventional wash-off process. Ozone gas was directly injected into a specially designed jet dyeing machine during wash-off. This was done in such a way that only unfixed dyes were destroyed. Fixed dyes on the fabric did not undergo any discoloration or damage. The performance of the new wash-off method was investigated for a number of shades. The results showed that controlled addition of ozone in the wash-off liquor produced dyeings having identical color depth and fastness. The new method also significantly reduced the process time and the color and quantity of the wash-off liquor, thus proving to be an environmentally friendly process. The new wash-off method was used at ambient temperature, thus the energy cost was expected to be much lower than that of the conventional wash-off.