Functions of Trace Metals in Fibers on Dyeing of Wool Fiber with Oxidation Dyes

Abstract

To clarify what components of CMC contribute to the oxidation reaction, the effects of pretreatment of wool fibers using ethylenediaminetetraacetic acid (EDTA) solution and premordanting with the solution of metal salts on the dye uptake of the dinuclear oxidation dyes into wool fibers were investigated. The dye uptake of the wool samples pretreated with EDTA solutions decreased apparently compared to that of the intact wool sample. On the contrary, the wool samples premordanted with copper, iron and nickel salts allowed the dye uptake of oxidation dye inside the wool fiber to increase. These findings indicate that the metal ions presented primarily within the intercellular materials play an important role in developing the colored oxidation dye on⁄into the fiber. The presence of transition metal ions in the intercuticular material causes hydrogen peroxide to undergo radical decomposition, leading to oxidizing species by means of Haber-Weiss mechanism. They take part as initiator of oxidation reaction, where the dye precursor is electrochemically oxidized to its corresponding Wurster salt.