Comparative study on traditional indigo dyeing onto cotton fabric using ripe banana and sodium dithionite as reducing agents

Abstract

© 2015, Chemical Publishing Co. All rights reserved. In most industrial and conventional dyeing processes, indigo dye reduced in a high alkaline which sodium dithionite is of major importance. However, the processes involve many economical, ecological and technical problems. In this study, sodium dithionite and also ripe banana were used as reducing agents for indigo dyeing onto cotton fabric. Their capability of indigo reduction and also their kinetic and thermodynamic studies of indigo dyeing were investigated using UV-visible spectroscopy at λmax 410 nm. Results revealed that under the same reduction condition of pH-13, 30°C, sodium dithionite exercised its superiority in terms of reducing time, the amount of reducing agent and yield of reduced indigo over ripe banana. In addition, the kinetic data evaluated via pseudo-second order model reveals that the activation energy of dyeing process using sodium dithionite as reducing agent was lower than the energy required to dye cotton fabric using ripe banana. Moreover, the adsorption studies of indigo dye on cotton fabric indicated that both reducing agents fitted well with the Langmuir model and their adsorption processes are exothermic and spontaneous. However, the cotton fabric dyeing using ripe banana as reducing agent gave lighter color measured in term of its lightness compared to using sodium dithionite.