Characterization and Thermodynamics of a Natural Mineral Dye-Based Chromium Complex Dye on Cotton Fabric

Abstract

 Transition metal complex of a bisazo dye derived from p-phenylenediamine extracted from a natural mineral dye
and p-nitroaniline was synthesized with the azo dye acting as ligand for the metal complex dye. The ligand, azo dye
and the metal complex were characterized using UV-visible spectroscopy, IR spectroscopy and GC-MS. The IR
spectroscopy of both the ligand and the complex reveal the presence of azo group (N=N) at 1597 cm-1, N-O at 1384
cm-1 and other Metal-Ligand (M-L) bonds at 418 cm-1. The results were used to establish the type of metal complex
formed to be 1:1 (metal: ligand) and possible structure of the complex was proposed. The metal complex dye was
applied on cotton fabric and the thermodynamics parameters of the dyeing process were determined. These
parameters included the enthalpy change which was -58.94 KJmol-1 and the entropy which was 0.159 KJmol-1. The
thermodynamics studies of the dye showed that the dye has high substantivity and fastness that can be useful in
dyeing fabric.