Preparation Of Spported Iron-based Catalysts And Study On The Properties Of Activated Persulfate

In advanced oxidation systems,iron oxides are often used to activate persulfate to degrade organic pollutants in wastewater,among which goethite（Fe OOH）and hematite（Fe₂O₃）are the most representative.In order to explore its catalytic performance under different carriers,cellulose acetate（CA）and graphene oxide were used as carriers to synthesize supported iron-based catalysts by different preparation methods,and the adsorption,redox and electron transfer of supported iron-based catalysts at the molecular and atomic levels were elaborated through characterization analysis and catalytic degradation experiments,and the reaction mechanism was further explored.The specific contents are as follows:（1）Using cellulose acetate as a carrier material,iron based cellulose microsphere catalyst（CA Fe）was synthesized using single-phase droplet microfluidic technology.The microspheres were characterized by scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）,Fourier transform infrared（FTIR）spectroscopy,etc.Using tetracycline hydrochloride（TCH）as the target pollutant,the effects of microsphere catalyst dosage,PDS concentration,and TCH concentration on the catalytic degradation experiment were investigated.The results indicate that CA-Fe microspheres have good catalytic performance.The degradation mechanism of TCH was studied by radical quenching,electron paramagnetic resonance（EPR）experiments and X-ray photoelectron spectroscopy（XPS）,and the main active radicals in the reaction process:sulfate radicals（SO₄^-·）and hydroxyl radicals（·OH）.（2）Graphene oxide aerogels（r GO-A）,iron-based graphene aerogels（Fe-r GO-A）and nitrogen-doped iron-based graphene aerogels（Fe/N-r GO-A）were prepared by hydrothermal method and vacuum freeze-drying technology,and the crystal structure of the catalyst and the morphological changes of aerogels after Fe and N doping were observed by X-ray powder diffraction（XRD）electrochemical experiments（EIS and I-T）,BET,SEM and FTIR.The adsorption and degradation ability of aerogel catalysts to TCH was systematically studied.The results showed that the initial TCH solution concentration was 20 mg·L^-1,persulfate concentration of 3 mmol·L^-1,aerogel catalyst is 0.2 g·L^-1,initial p H value is 2.9,r GO-A has the best adsorption effect among the three synthetic aerogels,and Fe-r GO-A has the highest activation and degradation ability.Based on the overall situation of adsorption and degradation,the order of capacity of the three catalysts was Fe/N-r GO-A>Fe-r GO-A>r GO-A.In addition,the degradation effect of the Fe/N-r GO-A/PDS system under the influence of humic acid（HA）and anions was also studied.When exploring the mechanism,it was found that free radicals and non-free radicals jointly participated in the catalytic degradation of TCH,and the main active substances were SO₄^-·,·OH and singlet oxygen（¹O₂）.Its good stability is proved by the reuse of Fe/N-r GO-A.Therefore,the Fe/N-r GO-A/PDS system is of great significance in organic wastewater treatment.（3）In the process of synthesizing aerogel catalysts,the defective agent benzoic acid（HBC）was added to prepare a nitrogen-doped iron-based graphene aerogel（Fe/N-r GO-HBC）,which was characterized and compared with Fe/N-r GO-A for XRD,SEM and EDS.The adsorption and catalytic properties of Fe/N-r GO-HBC and Fe/N-r GO-A in removing TCH were systematically studied,and it was found that the Fe/N-r GO-HBC/PDS system had better degradation efficiency for pollutants,and the influencing factors（PDS dose,catalyst dosage,initial p H value and TCH concentration）were experimented.In addition,in order to further explore the degradation of catalysts in different types of pollutants,TCH,dye acid orange（AO7）and phenol were selected as target pollutants to compare the degradation under different pollutants,which is of great significance for the application of catalysts in actual wastewater.