Impregnation and Exhaustion Bleaching of Cotton with Peracetic Acid

Abstract

Cotton fabric was bleached with equilibrium peracetic acid in an exhaustion process and in cold pad-batch, hot pad-batch, and pad-steam bleaching processes. Exhaustion bleaching proceeded for 40 minutes at 60 °C and pH 7.5 with different concentrations of Persan S15 (peracetic acid produced by Belinka, Slovenia). Pad-batch processes were conducted with storage for different times at room temperature or at 60 °C. Two bleaching baths with 15 and 60 ml/l of Persan S15 were used for the impregnation processes. Pad-steam bleaching was also performed; the samples were steamed immediately after padding with bleaching solution or after cold/hot storage. The degree of whiteness achieved with elongation of storage time was measured. The influence of different bleaching conditions on damage to the cotton fabrics was evaluated by measurements of the degree of polymerization and the breaking strength of the fabrics. It was established that the achieved whiteness values depend on the concentration of the bleaching agent, temperature, and time of treatment. The exhaustion bleaching and both types of pad-batch bleaching with low concentration bleaching solution are very convenient processes for bleaching of cotton fabric with peracetic acid. The pad-steam process did not prove appropriate. The breaking strength of the fabric did not deteriorate remarkably with any of the processes, but the degree of polymerization of the fibers revealed that damage occurred at high concentrations of bleaching agent.