Effect of ultraviolet irradiation and hydrogen P eroxide on the degradation of orange II using Fe(III) and Mn(II)

In order to enhance the treatment effect of water and wastewater, Fe(III) (Fe(NO₃)₃·9H₂O) and Mn(II) (MnSO₄·H₂O) were used for the degradation of azodye Orange II. The effect of ultraviolet irradiation and hydrogen peroxide were investigated. It was observed that Fe(III) and Mn(II) had similar decolorization efficiency. Nevertheless, in the presence of hydrogen peroxide, the decolorization efficiency using Fe(III) was especially higher than that using Mn(II). Under 254 nm ultraviolet irradiation, the decolorization efficiency achieved 96.8% and 82.7% at 5 min for Fe(NO₃)₃·9H₂O and MnSO₄·H₂O in the presence of H₂O₂, respectively. But Under 365 nm ultraviolet irradiation, the efficiency of Mn(II) was found to be especially lower than that of Fe(III). The quenching experiments using iso-propanol indicated that a large amount of OH· radicals were generated during the degradation by Fe(III) using hydrogen peroxide whether under ultraviolet irradiation or not.