Dyeing Kinetics of CI Acid Orange 7 in Multiple Layers of a Chemically Modified Wool Fabric

Abstract

When the concentration distribution of an acid dye in multiple layers of a chemically modified wool fabric is investigated, the concentration distribution curves have a sigmoi dal shape. The adsorption isotherm is approximately described in terms of a Langmuir- type adsorption model. The dyeing rate curve shows the sorption delay during the initial stage of dyeing due to the diffusional boundary layer. We assume that the relationship between the diffusion coefficient Df, dye concentration C, and constant α takes the form Df = Df0 exp(α C). The diffusion parameters are estimated in such a way that the experimental data fit the theoretical curve of the concentration distribution based on the diffusional boundary layer model. The surface concentrations of the dye in multiple layers do not depend on the dyeing time, and they equal the equilibrium uptake. The constant surface concentration is explained by the affinity of the dye to the fibers.