| Complex dyeing wastewater component, high chroma and difficult biodegradation, its processing is always a difficult problem to printing and dyeing and sewage treatment industries. As the increasing of environmental standards, traditional wastewater treatment methods have been more and more difficult to meet the requirements of the new environmental protection. Advanced oxidation process have the most application prospect in treating the refractory wastewater with the characteristics of quick, strong oxidation ability, good decolorizing effect and no secondary pollution etc.In this paper, we provide a new thinking of sludge utilization and treatment of printing and dyeing wastewater. We prepare catalyst Fe/sludge by one step method with roasting the mixture FeSO4·7H2O and paper mill sludge, and establish heterogeneous Fenton to process methylene blue, optimize the preparation method, and characterized the catalysts. Then we investigate the impact of catalyst dosage, H2O2 dosage and initial pH, the stability of the catalyst, the degradation mechanism of methylene blue, The final results of this study could provide a foundation for practical application of the Fe/sludge heterogeneous Fenton catalysts in treating the refractory wastewater.We investigate the impact of the proportion of FeSO4·7H2O and sludge, roasting temperature and roasting time on the catalyst activity, the best preparation condition is FeSO4·7H2O and sludge mass ratio of 1:1, roasting 500℃ and 2h by the degradation effect and characterization results. Through the characterization of 100% sludge (PMS-500) and the best catalyst (PMS-Fe-500), the results show that compared with the PMS-500, specific surface area and total entrance of the PMS-Fe-500 is less. The Fe in PMS-Fe-500 exists in the form of α-Fe2O3, magnetic performance is good. The catalysts have mesoporous of 2-50 nm, and the SiO2 and Fe formed the key of Si-O-Fe.There was synergy between PMS-Fe-500 and H2O2, which has a good effect to methylene blue’s degradation. The best condition of heterogeneous Fenton in degradation of methylene blue which initial concentration is 100 mg/L, is that catalyst dosing is 1g/L, H2O2 is 4ml/L, and initial pH= 4. The decolorization rate can reach more than 90% after 2h, when TOC removal rate is about 70%, the effect of optimized reaction system for methylene blue treatment is good. There will not be a large number of sludge with iron after reaction, the catalyst has high value with the characteristic of stability and longevity.Methylene blue was damaged in the reaction process, without absorption peak at 664 nm at the end of the reaction, methylene blue decolorizing reaction basic completely. Methylene blue is broken into small molecule organism or CO2 and H2O. The degradation of methylene blue mainly depend on PMS-Fe-500 itself, instead of homogeneous Fenton by iron dissolution in solution. The reaction rate was positively correlated with catalyst dosing and H2O2 dosing, while negatively correlated with initial pH. The initial pH affect greatest to the reaction rate, and H2O2 dosing have the minimum effect on the reaction rate. |
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