Strong enhancement on Fenton oxidation by addition of hydroxylamine to accelerate the ferric and ferrous iron cycles

The Fenton system generates reactive species with high oxidation potential such as hydroxyl radicals (HO•) or ferryl via the reaction between Fe (II) and H₂O₂. However, a number of drawbacks limit its widespread application including the accumulation of Fe (III) and the narrow pH range limits, etc. The aim of this study is to propose a much more efficient Fenton-HA system which is characterized by combining Fenton system with hydroxylamine (NH₂OH), a common reducing agent, to relieve the aforementioned drawbacks, with benzoic acid (BA) as the probe reagent. The presence of NH₂OH in Fenton's reagent accelerated the Fe (III)/Fe (II) redox cycles, leading to relatively steady Fe (II) recovery, thus, increased the pseudo first-order reaction rates and expanded the effective pH range up to 5.7. The HO• mechanism was confirmed to be dominating in the Fenton-HA system, and the generation of HO• was much faster and the amount of HO• formed was higher than that in the classical Fenton system. Furthermore, the major end products of NH₂OH in Fenton-HA system were supposed to be NO₃^- and N₂O.