Low-temperature bleaching of cotton fabric by activated peroxide system

Abstract

Bleaching of cellulose material with hydrogen peroxide (H2O2) is carried out, in general, beneath alkaline stipulations at excessive temperature, which ends up in bigger energy consumption and fibre damage. This study was designed to achieve bleaching of cotton material at low temperature by utilising potassium persulfate (K2S2O8), which is a catalyst of hydrogen peroxide decomposition, to improve the traditional procedure. The variables affecting bleaching effects were investigated; the bleaching temperature was confirmed to have the greatest influence on activated bleaching, and the elevated temperature used was accompanied by tremendous improvement in whiteness. The whiteness index of the fabric bleached at low temperature was lower than that of fabric bleached at high temperature, but the tensile strength and weight loss were a lot better for the material bleached at low temperature. Subsequent Fourier transform infrared analysis indicated that the potassium persulfate/hydrogen peroxide bleaching system decreased carbonyl groups better than traditional bleaching did, leading to greater bleaching efficiency and final brightness. Bleaching by potassium persulfate/hydrogen peroxide resulted in stronger oxidation than by hydrogen peroxide bleaching. By calculating through a theoretical energy consumption analysis, it was found that the low-temperature process required 1·96 times lower energy than that for the traditional procedure.