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, p-hydroxybenzoate (pHBA). The addition of a radical scavenger, tert-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.