Dyeability of Acid Dyes on Wool Fabrics Treated with Pulse Corona Discharge and an Enzyme

Abstract

The wool fabrics were treated by pulse corona discharge, followed by a keratinase to obtain shrink-proofed wool fabrics. The effects of the dual treatment on surface modification and dyeability for three kinds of leveling acid dyes with one, two, or three sulfonate groups in the structure were investigated. Although the physical surface was almost unchanged by the pulse corona discharge judging from the SEM observation, the ESCA analyses showed that the components of C and S atoms were greatly changed by the discharge. From the surface chemical composition, it is likely that the lipid layer of wool was partly removed and the remaining one on the surface was oxidized to give -C-O-,-C=O and -COO- residues. Furthermore, the presence of cystine monoxide (-SO-S-), cystine dioxide (-SO2-S-), and cysteic acid (-SO3-) was confirmed after the discharge. The dyeing rate was increased considerably by the pulse corona discharge/enzyme treatment, but the equilibrium dye uptake was unchanged. The sorption isotherms obtained were analyzed using dual sorption mechanism consisted of the Langmuir and partition type sorption, and three sorption parameters, which are the number of binding site, S, the intrinsic binding constant for the Langmuir type sorption, KL, and the partition coefficient, KP are discussed.