Degradation Of Rhodamine B By Z-type Heterojunction CeO₂-BiOi Photocatalyst Coupled With

Rhodamine B（RhB）is a bright peach color artificial dye,also known as alkaline rose extract,its own toxicity is higher,at the same time has a strong fat solubility,so the residue in the human body is also high,human long-term contact will be carcinogenic,teratogenic risk,and the conventional method is difficult to effectively deal with,so the preparation efficiency is high,It is important to remove Rhodamine B with low cost catalyst.In this paper,CeO₂- BiOI Z-type heterojunction photocatalyst was prepared by solvothermal method.The microstructure and elemental composition of CeO₂-BiOI were systematically investigated. With Rhodamine B as the degradation object,the CeO₂-BiOI/PMS photocatalytic system was constructed.The performance and reaction mechanism of CeO₂-BiOI activation of persulfate were explored.The main research results are as follows:（1）In this paper,CeO₂-Bioi Z-type heterojunction photocatalyst was prepared by solvothermal method.The microstructure of the composite photocatalyst was characterized by SEM,and the microstructure of the composite photocatalyst was three-dimensional flower- like microsphere structure.CeO₂was evenly distributed on the BiOI layer,but the loading did not change the main structure of BiOI.According to EDX characterization,CeO₂-BiOI contains four elements,Ce,O,Bi and I,and the material has good crystal shape and sharp characteristic peaks.The two semiconductor characteristic peaks can be observed in the infrared spectra of materials with different CeO₂loading loads,and the slight deviation of characteristic peaks can confirm the successful curing of CeO₂on BiOI.CeO₂-BiOI is a kind of mesoporous material,and the doping of CeO₂can bring higher specific surface area,pore volume and pore size.The specific surface area of the composite was 55.75m²/g,and 30%of the nitrogen adsorption-desorption isotherm of CeO₂-Bioi was H₃type IV,which had a higher equilibrium adsorption capacity than BiOI.（2）Construct CeO₂-BiOI/PMS advanced oxidation system with RhB as the target pollutant.With the doping amount of CeO₂up to 30%,the removal rate of RhB reached97.8%.30%CeO₂-BiOI/PMS system followed the quasi-first-order kinetic model,the correlation coefficient was 0.9622,and the kinetic rate equation was y=0.0640x+0.3093.30%CeO₂-BiOI/PMS system had the best activation performance,and the reaction rate constant was 0.0640min-1.The reaction rates were 80 times that of 30%CeO₂/PMS/light system and 2.79 times that of BiOI/PMS/light system,respectively.When the catalyst dosage was 0.1g/L and the initial PMS concentration is 0.1g/L,the removal rate of 100mg/L RhB can reach 97.8%at 25^oC.In the range of p H 3-9,the removal rate of RhB can reach more than 95%.（3）The quenching experiment found that·OH and SO₄^-·did not act mainly on free radicals,but only played a small part in the reaction.¹O₂and h⁺were the main active groups.Electron para-magnetic resonance（EPR）tests also successfully detected ¹O₂and h⁺signals.UV-Vis spectra showed that the ethyl peak on RhB was destroyed,and the ethyl peak slowly disappeared with the passage of time.TOC detected that the mineralized rate of RhB was only62.5%,while the removal rate of RhB was 97.8%.Therefore,RhB was not completely mineralized,but was converted from macromolecules to small-molecule intermediates.