Diffusion/adsorption behaviour of reactive dyes in cellulose

The diffusion/adsorption behaviour in cellulose films of two monochlorotriazinyl (MT) reactive dyes having high substantivity to cellulose was investigated from the dyebath using a wide concentration range of sodium sulphate at 80 degrees C. Diffusion coefficients for these reactive dyes showed a large concentration dependence at low salt concentration and a smaller dependence with an increase in salt concentration. The concentration dependence of the diffusion coefficient or of the diffusion behaviour for reactive dyes in cellulose was essentially the same as that for direct dyes. From the results obtained the diffusion/adsorption behaviour of reactive dyes in cellulose could be explained by a variable porosity model in the low concentration range of the dyes. In the case of high salt concentration, the diffusion coefficients in cellulose increased with increasing dye concentration at which the saturated adsorption appeared. (C) 1997 Elsevier Science Ltd.