Clay nanoadsorbent as an environmentally friendly substitute for mordants in the natural dyeing of carpet piles

The aim of this work was to assess the possibility of using a bentonite‐type clay as a promising substitute for mordants in the natural dyeing of wool with madder. Wool yarn was treated with nanoclay by using three conventional methods of pretreatment (before dyeing), simultaneous dyeing with madder in the presence of clay, and aftertreatment (after dyeing). Madder was used as a natural source of colorant. The scientific methods employed in this study included Fourier Transform‐infrared spectroscopy, ultraviolet‐visible spectrophotometry, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, moisture regain measurement, tensile strength tests, reflectance spectrophotometry, and fastness evaluation. The intensity of the major peaks in the Fourier Transform‐infrared spectra of the nanoclay‐treated wool yarn indicated chemical changes in the polypeptide functional groups in the wool structure. Madder exhibited higher dyeing properties on clay‐pretreated samples compared with untreated wool. The results of colour measurements showed that the colour strength of the dyed samples improved with an increasing amount of clay in the pretreatment baths.