| The traditional Fenton technology will produce a large amount of iron-containing sludge during the application process,and there is secondary pollution,which is difficult to follow-up and increases the processing cost.At present,some scholars have used iron-based or other compounds containing transition metal elements to prepare heterogeneous Fenton catalysts by ion exchange,co-precipitation,chemical deposition,high-temperature calcination,etc.,for Fenton reaction,which has received more and more academic circles attention.P-nitrophenol(PNP)is a nitroaromatic compound.It is widely used as a chemical intermediate in the printing and dyeing,pharmaceutical synthesis,rubber manufacturing,plasticizer manufacturing industries.Into the water is an organic matter that is difficult to be biodegraded and must be chemically treated for advanced treatment.In this study,Fenton sludge was modified by calcination and deposition,and the transition metal copper element was loaded on the surface.Two heterogeneous catalysts with heterogeneous C/Cu doping were prepared and used for PNP degradation.Based on the degradation effect.The mechanism of the degradation of PNP by heterogeneous catalyst was investigated.At present,there are few studies on the reuse of iron-containing sludge.My study found that the main component of the Fenton iron sludge is iron oxyhydroxide.The coking wastewater has a certain catalytic degradation effect,and the recovered iron sludge can be used as a raw material.A novel heterogeneous catalyst is prepared and the pH range of the catalyst is improved.The feasibility of repeated use of iron-containing sludge was verified by experiments.The results showed that the main component of the recovered Fenton sludge was iron oxyhydroxide.The removal efficiency was 42%when the initial pH was 3.5,the concentration of H2O2 was 0.8 g/L,and the H2O2/Fe(II)molar ratio was 10:1,the reaction was 48 h.Therefore,the recovered iron sludge can be used as a raw material to prepare a novel heterogeneous catalyst,and the pH range of the catalyst can be improved.In this paper,Fenton iron sludge was modified by calcination,deposition,etc.,and two kinds of heterogeneous catalysts Fe2O3/C/CuO and Fe3O4/C/CuO were prepared by loading transition metal copper on the surface.The materials were characterized by SEM,XRD,FTIR,TGA,BET,etc.to understand the phase composition,surface functional groups,crystal structure and other information of the catalyst.The preparation conditions of the catalyst were optimized.For the Fe2O3/C/CuO material,the aerobic calcination temperature was controlled at 600?,and the copper element loading was 30%,the PNP removal rate was 98%.For the Fe3O4/C/CuO material,when the copper element loading was 15%,the degradation effect on PNP is the best,and the removal rate reaches 94%.The response surface method(RSM)was implemented for the optimization of the process.When catalyst concentration was 1.75 g/L,H2O2 concentration was 0.15 mol/L,degradation time was 6 h,the PNP removal rate was expected to be 99.67%.The removal rate of PNP is still above 98%after repeated 5 times.When Fe3O4/C/CuO degraded PNP,the catalyst concentration was 1 g/L,H2O2 concentration was 0.2 mol/L,and the reaction rate was 3 h.The removal rate of PNP reached 94%.The material is less stable than the Fe2O3/C/CuO material after repeated use 4 times,the PNP removal rate was reduced to 76%.The catalytic mechanism of heterogeneous catalysts Fe2O3/C/CuO and Fe3O4/C/CuO and the possible mineralization mechanism of PNP were analyzed by EPR and LC-MS characterization.The p-nitrophenol undergoes an ortho and para substitution reaction with ·OH,then oxidized to hydroquinone and benzoquinone.The carbon-carbon double bond is broken to form an organic acid compound,which is finally converted into CO2 and H2O. |
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