Heterogeneous Catalytic Oxidation of Methyl Orange Dye by Copper(II)- Benzoic Acid Complex/NaHCO3/H2O2 System

Azo dye waste water is a serious problem because of the high yield, the low biodegradability and the high toxicity. In this work, the heterogeneous Fenton process was employed to degrade methyl orange (MO) using Copper(II)-benzoic acid (CuBA) as the catalyst in the HCO3- solution using H2O2 as the oxidant. CuBA was prepared by a complexing reaction. It was analyzed by FTIR and catalytic activity. The effects of different parameters on the degradation efficiency of the process were studied. The results were found that 90.8% MO degradation efficiency was achieved within 30 min under the best conditions of initial pH 7.0, 1.2 mM of CuBA, 25 mg/L of MO, 10 mM of NaHCO3 and 0.40 g/L (m/V) of H2O2 at 40C. The kinetics of degradation of MO followed first-order reaction kinetics. A possible pathway of MO degradation was also proposed based on the detected intermediate products by UV-Vis, IR, mass spectrometry. MO was effectively degraded by CuBA/NaHCO3/H2O2 under the neutral and alkalic conditions. The CuBA/NaHCO3/H2O2 system overcomes the two problems faced by the homogeneous Fenton process.