Photo-Fenton oxidation and mineralization of methyl orange using Fe-sand as effective heterogeneous catalyst

Abstract

A novel heterogeneous photo-Fenton catalyst, iron coated sand (Fe-sand) was synthesized by impregnation-calcination method. The catalyst Fe-sand was characterized by XRD, BET, SEM, TEM, FTIR, XRF and DRS methods. X-ray diffraction (XRD) analysis showed that the Fe-sand catalyst mainly consists of Fe2O3 and SiO2 crystallites, and the Fe concentration of the prepared catalyst measured by AAS is 135.7 mg/g. BET results revealed that Fe-sand possess a mesoporous structure with a porosity of 23%. The catalytic performance of the Fe-sand was studied in the discoloration and mineralization of methyl orange (MO). The influence of reacting conditions on degradation efficiency of the oxidation process was analyzed. At optimal conditions (200 mg/L of H2O2, 100 mg/L of initial MO concentration, pH = 3 and without added alcohol) complete discoloration of MO can be obtained within 60 min. The reaction process of MO discoloration was followed by UV–vis and GC–MS spectroscopic techniques. Based on the oxidation products formed, a probable degradation mechanism has been distinguished. Leaching tests indicated a very low concentration of dissolved iron ion and satisfactory stability of prepared catalyst. Industrial application of this catalyst in textile effluent treatment has shown that the proposed catalytic process is suitable for producing reusable water quality.