Degradation Of Indigo Carmine Wastewater By Activated Persulfate Over Iron-based Catalyst Enhanced By High Gravity

Efficient removal of origanige pollutants in dyeing wastewater is a very important issue in the field of wastewater treatment.Heterogenous Fenton-like technology provides an efficient way to degrade origanige pollutants in dyeing wastewater.However,most development Fe-based heterogenous Fenton-like catalysts are faced with problems such as slow Fe³⁺/Fe²⁺cycling,limited interfacial transport rate,low efficiency under alkaline conditions.Therefore,the research was focused on solving above problems in the traditional Fe-based heterogenous Fenton-like catalysts.The aim of dissertation is to construct highly efficient and stable heterogenous Fenton-like catalysts through controlling the metal composition and the support of the catalysts.Indigo carmine（IC）was chosen as the model pollutant to evaluate the performance of catalysts.Firstly,Fe~0/Fe₂O₃/OMSi as a bimetallic catalyst was designed to activate persulfate to degrade IC dyeing wastewater.The Fe~0/Fe₂O₃ nanoparticles supported on ordered mesoporous silicon（OMSi）by impregnation method.Fe~0/Fe₂O₃/OMSi processes ordered mesoporous structure with high surface area and pore volume,uniform pore size,highly dispersed and Fe~0/Fe₂O₃ active species by using X-ray photoelectron spectroscopy（XPS）,Scanning Electron Microscope（SEM）,and Automatic specific surface area porosity analyzer（BET）.SO₄^·-and·OH were produced in the solution which was proved by EPR.In the fast reaction stage,the degradation rate of IC is positively correlated with PS concentration and reaction temperature.Strongly alkaline environment and the increase of Fe~0 dosage ratio had a significant promoting effect on the degradation rate.PS/Fe~0/Fe₂O₃ oxidation process at initial pH was 12,PS concentration was 5×10^-3 mol/L,dosage ratio of Fe~0/OMSi and Fe₂O₃/OMSi was 12:18,temperature was 60℃,The degradation rate of IC could reach 95%within 30 minutes.A two-stage oxidation process was composed of slow heterogeneous reaction and fast homogeneous reaction was founded in the IC degradation.Secondly,FeS₂ as catalyst was used high gravity reactor packing to form a system of FeS₂-PS in a high gravity field to degrade indigo dye IC wastewater.The surface structure of FeS₂ is still relatively smooth before and after the oxidation reaction,and the microstructure didn,t change significantly by using SEM;S^-on the surface of FeS₂filler provides electrons for the redox cycle of Fe（III）/Fe（II）was proved by XPS;The FeS₂-PS system does produce two active oxide species SO₄^·-and·OH;under the condition of pH was 12,PS concentration was 5×10^-2mol/L,high gravity factorβwas48,and liquid flow rate was 20 L/h,The removal rate of 150 mg/L IC reached 96%by FeS₂ activated PS oxidation process in high gravity field within 20min;The oxidative degradation of IC presented a two-stage oxidation mode,a slow heterogeneous reaction and a fast homogeneous reaction;the intermediate products in the IC degradation process were analyzed by GC-MS,and the possible path for IC to be oxidatively degraded was deduced,indicating that IC can be oxidatively degraded.It is effectively degraded by RPB-FeS₂-PS.This research develops new materials and technology for the efficient removal of organic pollutants.It can also provide pathway and theoretical foundation for the design and application of heterogeneous Fenton catalysts,which has promising scientific significance and application prospects.