An environmentally responsible polyester dyeing technology using liquid paraffin

Abstract

Two major challenges for sustainability of the textile industry are water consumption and hazardous industrial effluents. A solvent dyeing technology for polyethylene terephthalate fabrics was developed to facilitate the reduction of chemical consumption and to eliminate the use of water. Liquid paraffin was selected as the optimum dyeing medium from a collection of 110 organic solvents using a combination of Hansen solubility parameters and environmental, health, and safety profiles. The solvent dyeing method developed in the present work offers three advantages over traditional aqueous dyeing: high quality dyed goods without using water and auxiliaries, efficient reduction of surface oligomers without additional reduction cleaning and easy reuse of spent dye liquors. As a result, negative environmental impacts can be minimized compared to conventional aqueous process. Substantial savings in chemicals (115 kg per metric ton of dyed polyester) and water (70 m3 per metric ton of dyed polyester) can be achieved. The result of a 7-cycle reuse sequence demonstrates excellent color consistency of dyed fabrics. By implementing the principle of reducing waste, reusing, and recycling resources, the solvent dyeing process developed in this study effectively reduces the consumption of chemicals and eliminates the use of water. Compared with traditional aqueous dyeing method, the solvent dyeing is a promising alternative technology for the protection of scarce freshwater resource and for sustainability of the textile industry.