Recent Progress in Waterless Textile Dyeing

Two new processes of waterless textile dyeing known as air-dye and supercritical carbon dioxide (scCO2) assisted dyeing is reviewed and discussed. The conventional textile dyeing industries use freshwater as a solvent and drain them as wastewater. Each year trillions of freshwater and over ten thousand dyes and pigments are used globally. The wastewater from these industries is dumped into the surrounding lakes, agricultural fields, rivers, etc. The impact of textile dyeing is therefore significant because it decreases the freshwater level and polluting the surface water unceasingly. Thus, from decades, researchers have tried to develop a technology that is waterless and pollution-free. Because of researcher’s tremendous efforts, two such waterless dyeing method is in our hand now. These processes have multiple advantages over conventional techniques, such as emission of less waste and less greenhouse gases, shorter operating time, less energy consumption, etc. Moreover, they have good diffusivity, readily available, reusable, non-flammable and non-toxic, making the process economically feasible and environmentally attractive. Several textile converters in Europe, Asia and North America currently use AirDye. scCO2 method has gained the attention of brands such as Nike, Adidas and IKEA, all of whom have used this process to dye their own products. With versatile advantages, there are some drawbacks. Such as the dyeing is only applicable to synthetic fabrics like polyester and the installation of machines are relatively expensive. In this report, the current status of research and development on resolving several issues like this is also summarized.