An Investigation on the Catalytic Degradation of Dyeing Wastewater with Fe-ZSM-5 Zeolite

A homogeneous ferrous salt catalyst was used in the traditional Fenton oxidation technology for dyeing wastewater. However, it was difficult to avoid the secondary pollution and loss of ferrous ions. Zeolite catalysts, which are more efficient and environmentally friendly than conventional catalysts, have good prospects in the field of catalytic oxidation of dyeing wastewater. In this article, Fe-ZSM-5 zeolite catalyst was prepared by the liquid ion exchange method to replace the traditional ferrous salt catalyst and its catalytic effect was studied for wastewater treatment with the Fenton reagent. X-ray Diffraction was applied to study the characteristics of the Fe-ZSM-5 zeolite catalyst. The result indicated that the Fe-ZSM-5 well reserved the structures of a molecular sieve, which improved the catalytic effect. The effect of the number of ion exchanges and supported Fe on the structure of ZSM-5 zeolite is discussed in this paper. The treatment of dyeing wastewater by catalyzer of Fe-ZSM-5 and oxidant of H₂O₂ has been investigated under the optimal conditions of temperature, pH value, dosage of Fe-ZSM-5 and reaction time. Results show that Fe-ZSM-5 zeolite catalyst has excellent catalytic effect and the decolorization rate of the dye was to 98.5% under optimal conditions. The catalytic effect of the heterogeneous Fe-ZSM-5 was 3% higher than that of the traditional Fenton oxidation technology. Moreover, the residuals of Fe were significantly different between the two methods, which demonstrate that the heterogeneous Fe-ZSM-5 catalyzer efficiently overcame the problems of the catalyzer loss and secondary pollution.