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 if the appropriate concentration of ferrous ions is present in the cotton fibers. The tris-2,2î-bipyridine ferrous ion complex (trischelate) is the catalytically active species, and sodium lauryl sulfate functions as a stabilizer for the peracid in the presence of the trischelate. The effects of pH, temperature, and concentrations of 2,2î-bipyridine, sodium lauryl sulfate, and ferrous ions on the kinetics and mechanism of peracetic acid decomposition have been investigated. Peracetic acid decomposition in the bleach solution is due mainly to alkaline hydrolysis without added ferrous ions and catalysis by the trischelate complex in solutions containing added ferrous ions. Overall decomposition follows the rate expression where k1 is the specific rate constant for alkaline hydrolysis and k3 is the specific rate constant for catalytic decomposition by the trischelate in the presence of sodium lauryl sulfate.