Absorption Kinetics and Thermodynamics of Cationic Dyeing on Easily Dyeable Copolyester Modified by 2-Methyl-1,3-Propanediol

摘要

In the paper, adsorption kinetics and thermodynamics of C.I. Basic Red 46 (BR46) on the 2-methyl-1,3-propanediol (MPD)-modified cationic dyeable copolyester (MCDP) fabric were investigated at the temperatures of 80, 90 and 100 degrees C. The adsorption data obtained at different temperatures were applied in pseudo-first-order and pseudo-second-order kinetic models. The pseudo-second-order model could be used to explain the adsorption kinetics more effectively and predict the rate coefficient (k(2)), equilibrium dye sorption capacity (q(e)), and the half dyeing time (t(1/2)) at different temperatures. In addition, the activation energy of adsorption (E-a) was determined based on the pseudo-second-order rate constant. The equilibrium data of adsorption were found to conform to Langmuir isotherm with the higher correlation. Moreover, the determined thermodynamic parameters including adsorption affinity (-Delta mu degrees) and enthalpy change (Delta H degrees) showed that the dye adsorption onto MCDP was a spontaneous, endothermic, and chemisorption process.