Thermodynamics and kinetics of cashmere dyeing with metal complex dye

Abstract

The optimal condition, kinetics and thermodynamics of adsorption of the metal complex dye onto cashmere fibre havebeen studied in order to evaluate the improvement of cashmere qualities under industrial dyeing conditions with metalcomplex dye. The optimal conditions for dyeing cashmere fibre are obtained at 85°C temperature, 2-13% initial dyeconcentration, 3.5 pH and 50 min treatment time. By reducing the temperature and operating time, qualities of cashmerefibre such as luxury and softness improve, and damage to fibres decreases significantly. As a consequence, opportunities forenhancement of cashmere product quality and industrial efficiency due to mild industrial conditions and lower energy needsare attained. The adsorption kinetics of metal complex dye onto cashmere fibre follow a pseudo-second-order kinetic modelwith an activation energy of 77.33 kJ·mol^-1. The Langmuir isotherm is found the best model for dyeing adsorption ontocashmere fibre. On the basis of thermodynamics, kinetics and diffusion models, both adsorption and diffusion are involvedin the process of dyeing cashmere, and an electrostatic attraction between dyeing molecules and cashmere fibre occurs.