Bleaching of cotton/lyocell fabrics with heterogeneous photocatalysis with titanium (IV) oxide under UV light and investigation of the effect of oxygen radicals on bleaching process

Abstract

Cellulosic fibers, generally, are not used as final product or get further textile processes such as dyeing, printing or finishing, unless they are bleached. In this study, cotton/lyocell fabrics were bleached with ultraviolet radiation accompanied by TiO2. Photocatalytic characteristic of TiO2 was utilized for bleaching. Oxygen radical generation from TiO2 surface under UV radiation was ensured. The effect of TiO2 concentrations between 1-300 g/L was investigated. Optimum pH, temperature and durations were determined for the best bleaching effect. Hydrogen peroxide bleaching was carried out and the results were compared with photobleaching. The changes on the tenacity and hydrophilicity characteristics of the fabric were investigated. Oxygen radicals in the TiO2 bleaching bath were determined with Electron Spin Resonance technique and fluorescein assay. An alternative environmental friendly bleaching method which depends on catalytic reactions was presented as a result of the performed experiments.