Carbonate-radical-anions, and not hydroxyl radicals, are the products of the Fenton reaction in neutral solutions containing bicarbonate

The Fenton reaction, Fe(H2O)(6)(2+) + H2O2 -> Oxidizing product, is of major importance in biology as the major cause of oxidative stress, and in advanced oxidation processes. It is commonly assumed that center dot OH is the product of the Fenton reaction. The results presented herein point out that center dot OH is indeed the oxidizing product in acidic solutions for [Fe(H2O)(6)(2+)] > [H2O2]; Fe-aq(IV) is the active oxidizing product in neutral solutions; in slightly acidic solutions for [H2O2] > [Fe(H2O)(6)(2+)] a mixture of center dot OH and Fe-aq(IV) is formed. However CO3 center dot- is the active oxidizing product in neutral solutions containing HCO3- even at low concentrations, i.e. under physiological conditions. The implications to our understanding of the origins of oxidative stress and of catalytic oxidations in advanced oxidation processes are discussed.