Initial Desorption Rate Research Articles

The Rates of Desorption of Level‐dyeing Acid Dyes from Wool

A study of the initial rates of desorption of level‐dyeing acid dyes from wool into sodium borate (borax) solution has indicated a linear relationship between the dye removed, expressed as a percentage of the total dye initially present, and the square root of the time. Activation energies of diffusion during desorption from wool have been determined for several dyes.The effects of method of application of dye, nature of dye, and nature of substrate on rates of desorption of acid dyes from wool have been determined. It is shown that the rate of desorption is controlled by the relative magnitudes of the forces of repulsion between the charged fibre and the dye anion and the forces of attraction, such as van der Waals, hydrogen bonds, etc., between fibre and dye. Any fibre modifieation which results in an increase in the number of free acidic groups, such as dyeing at low pH values, acid chlorination. or peroxide bleaching, increases the rate of removal of dye by alkaline solution.