Thermodynamics of adsorption of laccaic acid on silk

The hybrid-race silk yarn was dyed till equilibrium with natural lac dye (laccaic acid) and the thermodynamics of dyeing were investigated. The adsorption isotherm obtained was identified to be a Langmuir type. When the temperature increased, the partition ratio and the standard affinity decreased drastically, The values of heat of dyeing and entropy of dyeing were - 13.20 kcal/mol and-0.03 kcal/mol/K, respectively, The effect of memecylon used as a mordant on silk dyeing with lac dye was also studied. It revealed that using memecylon promoted the adsorption of laccaic acid on silk and increased the attraction between iaccaic acid and silk surfaces. (C) 2002 Published by Elsevier Science Ltd.