ADSORPTION OF SOME TEXTILE DYES ON POST-VANILLIN LIGNIN DURING ITS PRECIPITATION

The here investigated adsorption of some textile dyes on post-vanillin lignin (lignin V) was examined during precipitation of the lignin, Un der these conditions, not only the investigated cationic dyes adsorbed , but also the reactive ones, of anionic character. The cationic dyes adsorbed in all cases better than the reactive ones. Depending on the type of dye and equilibrium concentration, the obtained excessive adso rption reached values even up to 1.4 g per 1 g of lignin V, what made adsorb even up to 99.6% of the amount introduced to a sample dye. The determined adsorption isotherms were described with Langmuir' and Freu ndlich's equations with a close to 100% probability. Both in the case of the reactive dyes, which is obvious because of their anionic charac ter, and in the case of the cationic ones, the investigated adsorption process was of physical type.