Investigation on the natural indigo dye for cotton fabric by using supercritical carbon dioxide

Sammanfattning: Concerns about the environmental impact of the textile industry are increasing, and there is an urgent need to develop and implement sustainable technologies. In particular, the environmental impact of dyeing, which emits a large amount of wastewater and chemicals, is one production process that needs to be resolved. Dyeing using supercritical carbon dioxide is attracting attention as a technology that uses carbon dioxide as a solvent instead of water and eliminates liquid waste from the process. It is a development that allows dyeing to be carried out with less energy and a lower environmental impact. In this study, the experiment was done on the application of this supercritical carbon dioxide technology to the dyeing of natural indigo cotton. The aim of study is contribution to the development of dyeing methods with less environmental impact. Natural indigo has the hydrophobicity and non polar which might be compatible scCO2 dyeing, a sustainable and biodegradable dye, offers eco-friendly advantages and poses no harm to humans. In contrast, synthetic indigo raises concerns about waste generation and environmental persistence. It is suggested that the possibility of natural indigo in renewable raw materials could be used to create eco-experiences not only in the textile industry but also in new areas, such as in coatings, design and biodegradable products. The experimental results showed that dyed cotton fabric using supercritical carbon dioxide as a solvent but small coloration and polyethylene glycol as a swelling agent improved dyeability, but mathematical describing was still small. Swelling agent can support the dye penetration into cotton fabric for better coloration. Changes in dyeability were also observed by increasing the process parameters. In the future, it is hoped that the technology can be scaled up to the industrial level and contribute to reducing the environmental impact of the dyeing of denim, a product that has a significant impact on the market, and to reducing the environmental impact and water scarcity of the textile industry as a whole.