A Study on the Kinetic and Thermodynamic Parameters of Different Acid Dyes on Nylon 6 Fibers

In this work, the kinetic and thermodynamic parameters of acid dyes on nylon 6 were studied. Acid Sky Blue A, Acid Naphtol Red 6B, and Chrysophenine GX were applied on nylon6 and the dyeing process was conducted at specific conditions. In the early stages of dyeing the linear curve of percentage exhaustion against square root of time was plotted and the ratio of the second root of diffusion coefficient to fiber radius was obtained. Chrysophenine GX with a very high molecular weight, showed the maximum rate of diffusion, and exhaustion, and the lowest time of halfdyeing compared with Acid Sky Blue A and Acid Naphtol Red 6B. Also, adsorption isotherm of the dyes was investigated. The Langmuir type of adsorption was observed for Acid Sky Blue A, while in the case of Acid Naphtol Red 6B and Chrysophenine GX, Freundlich model of adsorption was obtained. The standard affinity of the dyes was calculated from the partition ratio, and Acid Sky Blue A showed the maximum value of standard affinity.