Activation of Oxygen and Hydrogen Peroxide by Copper(II) Coupled with Hydroxylamine for Oxidation of Organic Contaminants

This study reports that the combination of Cu­(II) with hydroxylamine (HA) (referred to herein as Cu­(II)/HA system) in situ generates H₂O₂ by reducing dissolved oxygen, subsequently producing reactive oxidants through the reaction of Cu­(I) with H₂O₂. The external supply of H₂O₂ to the Cu­(II)/HA system (i.e., the Cu­(II)/H₂O₂/HA system) was found to further enhance the production of reactive oxidants. Both the Cu­(II)/HA and Cu­(II)/H₂O₂/HA systems effectively oxidized benzoate (BA) at pH between 4 and 8, yielding a hydroxylated product, <i>p</i>-hydroxybenzoate (<i>p</i>HBA). The addition of a radical scavenger, <i>tert</i>-butyl alcohol, inhibited the BA oxidation in both systems. However, electron paramagnetic resonance (EPR) spectroscopy analysis indicated that ^•OH was not produced under either acidic or neutral pH conditions, suggesting that the alternative oxidant, cupryl ion (Cu­(III)), is likely a dominant oxidant