Strategies comparison of eliminating the passivation of non-aromatic intermediates in degradation of Orange II by Fe3+/H2O2

The degradation kinetics of Orange II by Fe3+/H2O2 was examined under various conditions in the presence of the non-aromatic organic intermediates such as malonic acid (MA), oxalic acid (OX) and EDTA. Various strategies were adopted to eliminate the passivation of the non-aromatic organic intermediates in the Fenton-like degradation of Orange II. UV irradiation, visible irradiation, hydroquinone (HQ) additive and their hybrid were used to accelerate the decoloration of Orange II; however, some of them were failed to show a good performance in the presence of non-aromatic organics, especially for the mineralization of Orange II. Aluminum ions additive released the ferric ions via a competitive chelation process, and accelerated the reaction obviously. From the decoloration and the mineralization data of Orange II, UV irradiation combined with Al3+ ion additive was regarded as the most favorable strategy for deep mineralization of Orange II by Fe3+/H2O2 in the presence of non-aromatic intermediates. However, by considering the decoloration of Orange II with moderate mineralization, the combination of visible irradiation and Al3+ ion additive might present the best performance.