Synthesis Of Iron Based MOFs Materials And Their Removal Of Origanic Pollutants From Wastewater

Organic pollutants exist widely in aquatic ecosystem and pose a serious threat to human health.Therefore,it is very important to treat organic pollutants in wastewater.The traditional Fenton process is an effective method to treat organic pollutants in wastewater.The Fe Ox catalyst used in Fenton process has such problems as easy loss of iron ions and difficult recovery of iron silt,which leads to low catalytic efficiency of the existing Fenton technology and difficult to meet the actual demand.Fe-MOFs not only have good porosity and adsorption performance,can effectively adsorb and enrich low concentration of pollutants,but also can be modified to further improve their catalytic performance and stability.This paper is mainly divided into three parts:（1）Five different types of Fe-MOFs were successfully prepared,and the differences of Fenton activity of Fe-MOFs were investigated;（2）Fe-MOFs are modified by doping copper to further improve Fenton catalytic effect and stability;（3）Flocculant-Fe-MOFs composite catalyst was prepared,which can be used to treat low concentration wastewater.（1）Five Fe-MOFs were prepared by hydrothermal method using Fe Cl₃·6H₂O as metal ion source and fumaric acid,terephthalic acid and homologic acid as organic ligands.XRD,FT-IR,SEM and other characterization proved that the catalyst was successfully prepared,and the activity of these five catalysts was investigated by using phenol as a model pollutant.Under the same reaction conditions,the degradation effect of phenol was as follows:MIL-101-Fe>MIL-53-Fe>MIL-88A-Fe>MIL-88B-Fe>MIL-100-Fe.（2）Fe-MOFs was modified by doping copper by vacuum-reduction method,and it was proved by XRD and TEM that copper was effectively inserted into the cavity of Fe-MOFs in the form of Cu^I.The results of EIS,XPS,catalyst performance and DFT calculation show that the addition of copper accelerates the Fe^III/Fe^II conversion of MIL-88B during phenol degradation,inhibits the loss of Fe ions,and improves the utilization rate of H₂O₂.The degradation experiment of phenol showed that 0.4Cu@MIL-88B sample had the best degradation effect.The optimal reaction conditions were as follows:at room temperature,acidic condition,catalyst 15 mg,H₂O₂ 100μL,phenol degradation rate reached 99%within5 min.If the degradation rate of phenol is the same,the amount of H₂O₂ in the composite material is only 30%of that of the pure Fe-MOFs,which greatly reduces the amount of H₂O₂.（3）Flocculant can adsorb and enrich organic pollutants,which is convenient for treating wastewater with low pollutant concentration.Fe-MOFs composite coated with flocculant was prepared by in-situ composite method.The armor cage structure of the flocculant can protect the core Fe-MOFs,greatly improving the stability of the composite catalyst in acidic solution.Phenol degradation showed that the best degradation effect was obtained when the mass ratio of Fe-MOFs to carboxymethyl cellulose（CMC）flocculant was 1:0.3.The catalyst still maintained good catalytic activity and stability after repeated reaction.