Enhanced self-catalytic degradation of CuEDTA in the presence of H2O2/UV: Evidence and importance of Cu-peroxide as a photo-active intermediate

A new insight into the degradation of CuEDTA with UV/H 2 O 2 was performed. It was found that the degradation was an UV-enhanced self-catalytic process with two main stages. The first was the induction stage in which cupric ions were produced in CuEDTA degradation with UV photolysis or/and H 2 O 2 oxidation . The second was the photo-catalytic degradation stage in which CuEDTA was oxidized by UV-enhanced cupric ion-based Fenton process. The degradation efficiency reached as high as 82.2% during 18   min, being 37.4 times higher than the efficiency sum of single H 2 O 2 oxidation and single UV photolysis. The enhancement effect can be contributed to the synergetic interaction between H 2 O 2 , cupric ion and UV, specially, to the excellent photo-activity of copper-peroxide intermediates. One of them was identified to be CuO 2 by analysis of its CE-C 4 D electropherograms, UV–vis adsorption spectra, FT-IR spectra, Raman spectra, especially XPS spectra. The enhancement mechanism was experimentally confirmed to be due to the acceleration of Cu(II)-to-Cu(I) transform by the photolysis of copper-peroxide intermediates, leading to the increasing CuEDTA degradation.