Low-temperature bleaching of cotton knitting fabric with H2O2/PAG system

Pentaacetyl glucose (PAG) is a common and cheap intermediate and has biocompatible, nontoxic, and renewable features. PAG was investigated as a bleach activator for H2O2 in the pretreatment of gray knitting cotton fabric. The bleaching performance of the H2O2/PAG bleaching system was investigated by measuring the CIE whiteness index (WI), H2O2 decomposition rate and bursting strength. By addition of PAG, the WI and H2O2 decomposition rate increased significantly at 70 °C with little damage to the strength. The effects of temperature and pH value on WI were also considered. Due to its environmental advantages, the H2O2/PAG system showed a good applied prospect. By using benzenepentacarboxylic acid as a fluorescent probe for HO· detection, it was found that PAG could strongly promote HO· generation and that the concentration of HO· was closely related to the WI of the fabric. On this basis, a bleaching mechanism of the H2O2/PAG system was proposed.