Zirconium Oxychloride as a Novel Mordant for Natural Dyeing of Wool Yarns

Zirconium oxychloride, a well-known flame retardant, is introduced as a novel mordant for wool dyeing. This has been indicated by mordanting of wool yarns with zirconium oxychloride in different conditions and then dyeing with madder as a famous natural dye. The tenacity, color coordinates, washing, and light fastnesses of the dyed wool confirmed the positive influence of zirconium oxychloride as a useful mordant for wool dyeing with a low impact on the color coordinates. Further, an appropriate washing and light fastness were obtained for the zirconium-oxychloride-mordanted wool yarns. The central composite design (CCD) was used to design the experiments with four variables on the results of tensile strength. Statistical analysis confirmed the optimum conditions obtained through the experimental results. 1. Introduction Wool with high water absorption, good dye ability, high elasticity, reasonable bulkiness, and fire resistance has been used in clothing and floor coverings [1]. The dyeing of wool also poses a challenge for textile chemists due to its complexity of chemical and physical structure [2]. Wool yarns were initially dyed with natural dyes which then the dyeing process improved and transferred from one generation to the other. Although the consumption of natural dyes is high, it has been decreasing by the invention of synthetic dyes. Natural dyes were replaced by synthetic dyes due to their ability to easily match a desired color, increasing variety, high purity, cheap price, and easy processing. However, through production and application of synthetic dyes, producers and consumers have observed several ecological and biological problems [3]. Recently, an interest of using natural dyes in textile coloration has been growing due to the environmental regulation appearing in response to the toxic and allergic reactions associated with synthetic dyes. However, natural dyes are friendly to the environment and exhibit better biodegradability with higher environment compatibility [4]. Madder is a main source of a natural dye producing a variety of anthraquinone dyes in its roots and rhizomes. The main components are di- and tri-hydroxy-anthraquinones, alizarin and purpurin and their derivatives; ruberythric acid (alizarin-primeveroside), pseudopurpurin, and lucidin-primeveroside. Rubiadin, munjisti, quinizarin (1,4 dihydroxyanthraquinone), lucidin, nordamnacanthal, xanthopurpurin, and 1,8-dihydroxyanthraquinone are also identified from plant tissues [5–7]. Farizadeh et al. [8] determined the amount of alizarin, purpurin, and quinizarin in the Iranian