Degradation of Orange I by the zero-valent iron/hydrogen peroxide system

Abstract

The zero-valent iron/hydrogen peroxide system was very effective for the oxidative degradation of high concentration Orange I solution. The effects of Orange I initial concentration, hydrogen peroxide concentration, zero-valent iron dosage and pH value of solution on the degradation of Orange I were studied in this article. The concentration of iron ion, pH value and the content of Orange I in the reaction solution were determined by UV-VIS spectrophotometer and pH meter, respectively. The intermediate degradation products were determined by LC-MS. The experimental results showed that the Orange I solution with high concentration could be effectively degraded with low hydrogen peroxide concentration and iron powder dosage under acid condition. In addition, it can be speculated that in the process of degradation, Orange I was first dissociated into 4-(4-hydroxy-1-naphthylazo) benzenesulfonate, and then its chromophore was oxidized and broken, decoloring the reaction solution, followed by the generation to benzene sulfonate, nitrogen and 1, 4-naphthoquinone. After that, 1, 4-naphthoquinone was further oxidized to phthalate.