Bleaching of Colored Recycled Fibers, 1993 Pulping Conference Proceedings
CIE L*a*b* numerical analysis was used to rank various bleaching processes as to their effectiveness in removing various dyes from recycled fibers. A dye removal index was developed from the CIE L*a*b* numbers. Different colors and types of dyes reacted differently to each type of bleaching chemical.
CEDED and OZEPY were the most effective in removing dyes. The next most effective bleaches were ozone/hydrogen peroxide in sequence, and sodium hypochlorite. FAS would be the chemical of choice if you were forced to use a single stage application of a chlorine-free bleaching reagent. A single stage application of hydrogen peroxide was the least effective of all of the bleaching reagents that were tested. To most effectively remove dyes from recycled fiber a combination of bleaching chemicals would be required.
Bleaching of Colored Recycled Fibers, 1993 Pulping Conference Proceedings
