Environmentally Friendly Bleaching Process of Polyester Materials via Direct Process of Water without Heating System

A great quantity of chemicals, water, and energy are used during the bleaching of raw polyester (Polyethylene terephthalate) fabrics. For this aim, it is highly significant both economically and ecologically to develop eco-friendlier bleaching technology that removes the necessity for heat energy in the bleaching of these substrates. Here, we report on the green method for laboratory-scale bleaching with H2O2 in the presence of sodium pyrophosphate (Na4P2O7), which is used as both wetting agent and pH regulator and contributes to the high whiteness of fabrics. In bleaching, the process of water was used in ambient temperature as forte without any heating process, thus reducing the energy requirement significantly. In the measurements, it was observed that the whiteness value (W.I. = 74.1) was obtained after 10.0 hours of bleaching at 25°C. The SEM image of the polyester (PET) fabrics bleached with H2O2 for 10.0 hours indicated that few nano-sized remained (dusts, waxes and impurities) on the fabric bleached with H2O2 for 10.0 hours. In addition, it has been confirmed that PET fabrics bleached with this method have lowest damage on the fabrics (only 0.716% weight loss, insignificant mechanical reduction). This investigation demonstrated that PET fabrics can be effectively bleached in the presence of Na4P2O7/H2O2 without the necessity for any heating energy.