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Eco-friendly dyeing of wool and nylon using madder as a natural dye: kinetic and adsorption isotherm studies
Sadeghi-Kiakhani, M.
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 (Δμ°), free energy (ΔH°) and entropy (ΔS°) 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.
Keywords
Madder; Wool; Nylon; Dyeing; Adsorption isotherm
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