Influence of water on liquid ammonia-based sustainable dyeing of ramie fiber

Liquid ammonia dyeing emerges as an environmentally benign and sustainable option for the textile industry, characterized by a minimal ecological impact. However, its adoption is hampered by certain limitations, such as suboptimal dye exhaustion and issues with color uniformity, which present significant hurdles to its widespread industrial application. Building on the premise that the addition of water to an ethanol solvent can enhance reactive dye exhaustion in cotton fiber dyeing, this study delves into the dyeing behavior of ramie fiber using a water-liquid ammonia mixture with Reactive Red 195. The incorporation of water into the liquid ammonia solution was observed to marginally decrease the color strength (K/S value) of the dyed ramie fiber, compared to the dyeing with anhydrous liquid ammonia. This reduction is likely due to the diminished expansion of the amorphous regions within the fiber. However, the color levelness of the dyed ramie fiber was enhanced by the addition of water to the liquid ammonia. To decipher the influences on the dyeing process, the Taguchi method, utilizing an orthogonal array (L16), was applied. The analysis revealed that the dye mass factor was the predominant influencer (79.08 %), followed by the liquor ratio factor (18.53 %), with both factors demonstrating statistically significant effects (p < 0.05). A multifaceted analysis of the samples was conducted using advanced techniques such as XRD (X-ray diffraction), FTIR (Fourier transform infrared), TGA (thermogravimetric analysis), and SEM (scanning electron microscopy). These analyses confirmed that the water-liquid ammonia treatment induced changes in the samples’ properties. The treated samples exhibited lower barium activity numbers and breaking force values, indicating structural alterations. Furthermore, the molecular structure of Reactive Red 195 remained intact throughout the dyeing process in the water-liquid ammonia mixture, thereby affirming its viability for practical applications in the textile industry.