On the Fenton degradation mechanism. The role of oxalic acid

Abstract

Kinetics of Fenton (Fe(II) + H2O2) p-nitrophenol degradation reveal that the measured pseudo first-order rate constant is given by the expression: kobs = kK [H2O2]/(1 + K[H 2O2]), where K=20.3 × 102 M-1 is the equilibrium constant of formation of the complex Fe(II)-(H 2O2)n and k= 1.5 × 10-2 s -1 is the first order rate constant of degradation of the complex to yield Fe (III), OH and OH-. When oxalic acid is added, the complex Fe(III)-oxalic acid-H2O2 is formed producing a highly oxidized Fe(IV) species as the primary oxidant agent.