Production of Sustainable Textiles Using Natural Dye and Eggshell Powder on Recycled Polyester Fabric via Waterless Supercritical CO2 Dyeing

The growing environmental impact of conventional textile dyeing processes, particularly their high water consumption, chemical usage, and wastewater generation, has intensified the need for alternatives. For this reason, the textile industry faces increasing pressure to adopt sustainable production routes that minimize environmental loads. The utilization of recycled polyester fabrics, natural dyes, and waste-derived bio-resources within waterless dyeing systems represents a holistic approach toward environmentally responsible textile manufacturing. This study focuses on the production of sustainable textiles by dyeing recycled polyester fabrics with natural madder dye and eggshell powder in a waterless supercritical CO₂ medium. The samples were characterized via SEM, TGA, wash fastness tests, and tensile strength measurements. SEM images clearly revealed the presence of eggshell powder (ESP) on the fabric surfaces. After UV aging, the samples containing 20% ESP exhibited higher tensile strength and more pronounced color stability compared to the control sample. The CaCO₃ component of the ESP contributed to UV resistance, while the TGA results showed higher residual mass for ESP-treated samples, indicating improved thermal stability. Moreover, the persistence of ESP on the fabric surface after repeated washing and the satisfactory wash fastness results confirmed the durability of the treatment. Overall, the results demonstrate that the combination of natural dye, recycled polyester, and eggshell-derived bio-additives in a waterless scCO₂ dyeing system offers a promising and environmentally benign strategy for producing sustainable and functional textile materials.