Kinetics and thermodynamics of dye extracted from <i>Arnebia nobilis</i> Rech.f. on wool

Abstract

Kinetic and thermodynamic studies have been conducted with the crude dye extract of <i style="">A. nobilis</i> on wool fabric. On comparing the dyeing results of this dye with those of other natural dyes (juglone, lawsone and <i style="">Rheum emodi</i>), it is found that the diffusion coefficient of this dye is slightly lower. The dyeing mechanism corresponds to the partition mechanism, confirming that this naphthoquinonoid based colourant is adsorbed by wool fabric as a disperse dye. The dyeing process is exothermic. The rate of dye uptake, diffusion coefficient, standard affinity, heat of dyeing and entropy have also been calculated and discussed. Heat of dyeing and entropy are found to be negative.