Thermodynamic Sorption Parameters and Kinetics of Dyeing Disazo Dyes Derived from 4-aminobenzoic acid and 4-amino-3-nitrotoluene on Polyester Fibre and Polyamide Fibre

Abstract

The thermodynamic and kinetic properties of disazo dyes on polyester fibre and polyamide (nylon) fibre were investigated. The disazo dyes showed high affinity values on the two substrates under study. Some of the affinity values obtained on polyester fabric are -10.25, -12.10, -9.80, -10.35, -14.15 Kj.mol-1 at 363K and those obtained from nylon fabric are -10.03, -10.16, -10.26, -10.04, -10.3Kj.mol-1 at 343K for dyes I-V respectively. However, the affinity values of the dyes were slightly higher on polyester fibre than on nylon 6 fibre. It was also found that the enthalpy of dyeing, and entropy of dyeing values were slightly higher on polyester fibre than on the nylon 6 fibre. The enthalpy of dyeing values obtained on polyester fabric for dyes I-V are -838, -174.7, -15.9, -129.1, -741.8 Kj.mol-1 and those obtained on nylon 6 fabric for the same set of dyes are -223.4, -50.4, -65.9, -62.9, -88.0, Kj.mol-1. The entropy values obtained are -203, -448, -100, -53, -317, -177 Jmol-1k-1 at 363k on polyester fabric and -613, -114, -158, -149, -221 Jmol-1k-1 at 343K on nylon 6 fibre. The activation energy of diffusion results showed that there was high barrier to the mobility of dye molecules within the nylon polymer matrix due to steric effects and hydrogen bond formation between some functional groups of the dyes and the nylon polymer. The results of this study indicated that the dye-fibre interactions are thermodynamically allowed, which described the suitability of these practical dye applications on the synthetic fibres.