Preparation And Photocatalytic Activity Of Magnetic Metal-organic Frameworks Composites

Magnetic Metal-Oranic Fame works(MMOFs)are novel functional nanomaterials rising in recent years,which are made up of Metal-Oranic Fameworks(MOFs)and magnetic materials.MMOFs combine both the structural functions of MOFs and the magnetic features of magnetic particles,and greatly enhance their application scope.In this study,a new kand of composite photocatalyst was prepared by combining MMOFs with semiconductor photocatalyst,which not only had good photocatalytic performance,but also could be separated simply by a magnet.The main works were as follows:1.Based on the Fe3O4/MIL-101(Cr)materials,which were synthesized in hydrothermal method,the Ag/AgBr-Fe3O4/MIL-101(Cr)composites were prepared via a coprecipitation and photo-reduction.Moreover,a variety of characterization means were employed to analysis the catalysts and the results indicate that the Ag/AgBr-Fe3O4/MIL-101(Cr)not only retained the mesoporous structure of MIL-101(Cr),but also possessed strong magnetic properties and the composites could be separated rapidly.At the same time,a notable absorption extension in the visible-light region could be observed when Ag/AgBr was loaded on the Fe3O4/MIL-101(Cr).The RhB degradation experiments showed that the catalyst with 43.2 wt%Ag achieved the highest photocatalytic activity,while the corresponding photodegradation efficiency for RhB was 99.1%after 120 minutes irradiation on a dose 1.0 g/L.The O2-· and h+were the main oxidizing groups in the process of RhB degradation.The catalyst remained stable and highly activity after 5 times cycle experiments.2.The AgBr/Ag3P04-Fe3O4/MIL-101(Cr)composites were prepared by coprecipitation method.In addition,a variety of characterization means were employed to analyze the catalysts and the results showed that a notable absorption extension in the visible-light region could be observed when AgBr/Ag3PO4 was loaded on the Fe3O4/MIL-101(Cr).Beside,the catalyst could be rapidly separated by a external magnetic field.The RhB degradation experiments showed that the catalyst 1.0 BrP-FM achieved the highest photocatalytic activity,while the corresponding photodegradation efficiency for RhB was 99.8%after 30 minutes irradiation on a dose1.0 g/L.The catalyst remained stable and highly activity after 5 times cycle experiments.3.Oxytetracycline(OTC)and ofloxacin(OFL)were chosen as target pollutants,and the influencing factors during OTC and OFL degradation by AgBr/Ag3PO4-Fe3O4/MIL-101(Cr)were studied.Furthermore,the possible degradation pathway of OTC and OFL were also analyzed by HPLC-MS.The results showsed that when the initial pH was 7 and the catalyst dosage was 1.0 g/L the catalyst exhibited the highest efficiencies during OTC(30 mg/L)and OFL(20 mg/L)degradation,with 97.0%and 96.9%of degradation efficiencies for OTC and OFL,respectively.Additionally,the HPLC-MS analysis results showed that the oxytetracycline and ofloxacin generating a linear substance via aromatic ring opening,and further mineralized into CO2 and water.