The investigation of the effect of sodium chlorite and phosphonic acid catalysts on cotton bleaching process conditions

Today's environmental and living conditions necessitate reconsideration of traditional cotton fabric bleaching processes. For this reason, it is very important for the environment and the economy to obtain higher whiteness values by using less water and chemicals in bleaching. Sodium chlorite (NaClO2), the source of chlorine dioxide (ClO2) as the most important disinfectant, which gained popularity and availability during the COVID-19 pandemic, is an appropriate oxidant for the purpose. Using NaClO2 as bleaching agent has significant advantages, such as reducing the amount of washing proses and increasing of cotton strength. Another advantage of this reagent is that it causes less fabric weight loss than other reagents. Therefore, the present work was intended to improve the process conditions (different temperatures, concentrations, and times) of bleaching of cotton fabric by using NaClO2. Optimum temperature and time were determined as 30 min at 65 °C and 30 min at 85 °C, and a high whiteness index (W.I.=88) was obtained by using phosphonic acid (HEDP). Moreover, the tensile strength, weight loss and morphologies of the samples were examined. It has been observed that sodium chlorite causes little damage to cotton fibers and requires less water for rinsing since it does not form alkaline residues.