Studies on the adsorption of anionic dyes on chitosan

Equilibrium adsorption measurements of three anionic dyes on chitosan, under acid conditions, show that there is a 1 : 1 stoichiometry for the interaction of sulfonic acid groups on the dyes with protonated amine groups of the chitosan for mono‐, di‐ and trisulfonated dyes. Comparison of the extents of N‐acetylation calculated from equilibrium dye adsorption values with those determined by IR spectroscopy, for a series of chitosan samples covering a wide range of N‐acetylation values, demonstrates that equilibrium adsorption measurements may be used for the analysis of chitin and chitosan.