Kinetics of the decolorization by Fenton's reagent

Fenton's reagent was employed in the decolorization of aqueous solutions of one of three dyestuffs (Acid Red 27, Reactive Blue 81, Acid Blue 62). The decolorization with Fenton's reagent was found to be simple and fast. In or der to determine the reaction kinetics of the decolorization the stopped-fl ow technique under pseudo-first order conditions was used. Experiments were carried out at pH=2, at the excess of ferrous salts (FeCl2. 4H(2)O or FeSO 4. 7H(2)O). The rate constants of the decolorization determined by us are i n the same order of magnitude: 90 to 100 dm(3)/(mol.s) for FeSO4. 7H(2)O/H2 O2, and 40 to 50 dm(3)/(mol.s) for FeCl2. 4H(2)O/H2O2 systems. The differen ce between the rate constants for both ferrous salts indicates that the Fen ton's reaction may proceed via different mechanisms.