Eco-friendly dyeing of wool and nylon using madder as a natural dye: kinetic and adsorption isotherm studies

Abstract

In this study, dyeing, fastness and adsorption isotherm characteristics of madder natural dye on the wool and nylon yarns were investigated. Wool and nylon were first mordanted by aluminum sulfate, dyed with natural dye extracted from madder root, and the rates of dyeing and equilibrium times were determined and compared. Nylon, indeed, showed higher dyeing rate and reached equilibrium at comparatively lower times. Adsorption isotherms were identified to be a Nernst-type substrate. In addition, the affinity (Dl°), free energy (DH°) and entropy (DS°) of madder on the wool and nylon were calculated. The obtained results from thermodynamic data indicated that with temperature rise, the partition ratio and the standard affinity significantly decreased. The affinity of madder natural dye to the nylon was gradually higher as compared with wool. Wool, indeed, displayed higher negative values for both enthalpy and entropy changes as compared to those values of nylon. The colorimetric and fastness properties of madder natural dye on nylon were overall superior than on wool.

Thermodynamic and kinetic studies of the adsorption behaviour of the natural dye cochineal on polyamide 66

“…Standard affinity (−Δμ˚) is the thermodynamic parameter which strongly indicates the tendency of the dye to move from its standard state in the solution to its standard state in the fibre . This factor was specified as a difference between the chemical potential of the dye within the fibre and the chemical potential of the dye in the dyeing solution.…”

“…In general, dye adsorption on textiles is an exothermic process which releases heat energy . The amount of heat released during dyeing is influenced by the type of fibre, dye, and the dyeing media.…”

“…The dyeing process of fibres can be divided into four stages: (i) diffusion of dye in the solution; (ii) adsorption at the fibre surface; (iii) diffusion into the fibre; and (iv) fixation of the dye to the fibre . The operating variables in the dyeing process such as pH, temperature and usage of auxiliary agents affect the diffusion of dye into fibre.…”

“…The values of D/r 2 decrease as temperature increases because of decreasing diffusion rates associated with rising dyebath temperatures (Table 4). This behaviour indicates that it is the reverse reaction of the dyeing process and that desorption of dye molecules from polyamide is temperature-dependent [35,38,46]. It is evident that the adsorption of dye molecules on polyamide fabric plays a crucial role during the initial stage of dyeing.…”

Synthesis of ZnO Nanoparticles and Their Application for Printing Cotton Fabrics with Natural Cationic Dyes

“…The color strength (K/S) of the specimens was evaluated by the light reflectance technique using the Shimadzu UV/Visible spectrophotometer 11 . K/S in which K and S correspond respectively to the absorption and diffusion coefficients.…”