Absorption kinetics and thermodynamics of cationic dyeing on easily dyeable copolyester modified by 2-methyl-1,3-propanediol

Abstract

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 °C. The adsorption data obtained at different temperatures were applied in pseudo-first-order and pseudo-secondorder 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 (−Δμo) and enthalpy change (ΔHo) showed that the dye adsorption onto MCDP was a spontaneous, endothermic, and chemisorption process.