Grape Pomace (Vitis vinifera L.) Waste Valorization: Assessing Its Potential as a Sustainable Natural Dye for Textiles Applications

The present study aimed to explore the textile dyeing capability using dyes derived from grape pomace. Extractions were conducted with water at different pH levels and with a water/ethanol solution. Cotton (natural and cationized) and wool were employed in the dyeing process for varying durations (100 and 200 min). The colorimetric and fastness properties, in terms of washing (with hot and cold water) and exposure to natural light, were evaluated. The final color evaluation was performed using ΔE*, a parameter quantifying the magnitude of a color difference by comparing the L*a*b* color coordinates of the CIELAB system of the dyed samples with those of the control. The hues obtained on the fabrics resulted in uniform and earthy colors. However, the cationized cotton substrate showed the highest ΔE* values for all conditions used in obtaining grape pomace extracts, in the range of 33.91 to 37.98. This suggests that the surface treatment enhanced dye uptake, while organic cotton achieved a lighter earthy color. Natural dyeing using grape pomace presents a sustainable, ecological, and non-toxic alternative for textile dyeing, resulting in unique and earthy tones with commercial potential while promoting the sustainable use of natural resources and environmental preservation. The key to achieving sustainable development lies in waste reduction and valorization, along with the adoption of conscious consumption.