Decolourization and mineralization of commercial reactive dyes by using homogeneous and heterogeneous Fenton and UV/Fenton processes

Abstract

The oxidative decolourization and mineralization of three reactive dyes in separately prepared aqueous solutions C.I. Reactive Yellow 3 (RY3), C.I. Reactive Blue 2 (RB2) and C.I. Reactive Violet 2 (RV2) by using homogeneous and heterogeneous Fenton and UV/Fenton processes have been investigated. The effects of H 2O 2, Fe 2+ and Fe 0 concentrations, Fe 2+/H 2O 2 and Fe 0/H 2O 2 molar ratios at pH 3 and T = 23 ± 1 °C have been studied. Optimal operational conditions for the efficient degradation of all three dye solutions (100 mg L −1) were found to be Fe 2+/H 2O 2 = 0.5 mM/20 mM and Fe 0/H 2O 2 = 2 mM/1 mM. The experimental results showed that the homogeneous Fenton process employing UV irradiation was the most effective. By using this process, the high levels of mineralization (78–84%) and decolourization (95–100%) were achieved. Pseudo-first-order degradation rate constants were obtained from the batch experimental data.