2,2î-Bipyridine Catalyzed Bleaching of Cotton Fibers with Peracetic Acid

Abstract

Peracetic acid can be catalyzed to bleach cotton fibers at temperatures as low as 30°C by incorporating 2,2î-bipyridine in the bleach solution. Treatment of the fibers with HCl prior to bleaching reduces bleaching effectiveness by removing trace transition metal ions from the fibers. Sorption of individual ions (Cr+3 Mn+2, Fe+2, Fe+3 Co+2, Ni+2, Cu+2, and Zn+2) by HCl treated cotton fibers prior to bleaching indicates that the ferrous ion produces the greatest catalytic effect, and it is only effective when the metal ion is in the fiber as opposed to in solution. Ferrous ions in the fibers sorb 2,2î-bipyridine from solution to form the tris-2,2î-bipyridine ferrous ion complex that is associated with the fibers, and it is the trischelate associated with the fibers that catalyzes bleaching. The effects of pH, temperature, and concentrations of 2,2î-bipyridine, sodium lauryl sulfate, and transition metal ions (in the fibers and in solution) on bleaching effectiveness and peracetic acid decomposition have been studied, and a bleaching mechanism is proposed.