Preparation Of Ruthenium-based Composite Oxides And Their Photocatalytic Properties For Organic Wastewater

The lanthanide oxide photocatalyst has the advantages of special electronic structure,visible light absorption and narrow band gap energy,and is widely used in the fields of photocatalytic hydrogen production and water pollution purification.In order to enhance the absorption of more visible light and suppress the recombination rate of electron holes by lanthanide oxide photocatalyst,several ruthenium-based oxide composite photocatalysts were synthesized by hydrothermal method for photocatalytic degradation of methylene blue and hydrochloric-doxymycin and hydrochloric-tetracycline.The main findings are as follows:1)The Z-type composite photocatalyst Bi2O3/MoO3 was prepared by solvothermal method and mixed calcination method using Bi?NO₃?₃·5H₂O and Na₂MoO₄·2H₂O as raw materials.The morphology,microstructure and photoelectric properties of Bi₂O₃/MoO₃ composite photocatalysts were systematically tested by a series of characterization methods.The results of photocatalytic experiments show that the obtained Bi₂O₃/MoO₃ composites have higher photocatalytic activity than pure Bi₂O₃and MoO₃ for the degradation of methylene blue?MB?under visible light irradiation.This increased photocatalytic activity is primarily due to the efficient separation of photogenerated charge carriers by the Z-type system between B_i2O₃ and MoO₃.In addition,energy band calculation,free radical trapping experiments and photoluminescence spectroscopy?PL?results show that the photogenerated electrons on the MoO₃ conduction band combine with the photogenerated holes on the Bi₂O₃valence band under visible light,and the electrons simultaneously transition to the valence band of Bi₂O₃.The electrons reduce oxygen molecules to superoxide helium ions,and participate in the degradation of organic matter together with the holes on the valence band of MoO3.2)The heterojunction AgBr/Bi₄O₅I₂ composite photocatalyst with different silver iodide quality was synthesized by Solvothermal and chemical stirring method to control the addition of silver nitrate and Potassium bromide.UV-Vis DRS confirmed that the AgBr/Bi₄O₅I₂ composite photocatalyst increased its absorption of visible light,and the photoluminescence spectrum?PL?showed that the composite sample reduced the recombination rate of electron holes.The photocatalytic activity of AgBr/Bi₄O₅I₂composite photocatalyst with different silver iodide content was analyzed under visible light using hydrochloric acid-doxymycin?DC-HCl?.The experimental results show that The removal rate of DC-HCl on AgBr?5%?/Bi₄O₅I₂ composite photocatalyst was72.4%in 60 minutes,which was much higher than the photocatalytic activity of pure AgBr and Bi₄O₅I₂ under the same conditions.At the same time,the stability of AgBr/Bi₄O₅I₂ composite photocatalyst was also studied.After repeated use for four times,the photocatalytic performance did not decrease significantly.The removal rate of DC-HCl was between 72.4%and 70.0%.It has been proved by free radical trapping experiments that the hole is the dominant group of the system,participates in the redox reaction,and controls the progress of the photocatalytic reaction.3)The Ni²⁺doped Bi₄O₅I₂ ultrathin nanosheets with high specific surface area and excellent optical properties were successfully synthesized by one-step solvothermal method.The composition,morphology,light absorption,energy band and specific surface area of Ni²⁺/Bi₄O₅I₂ materials were systematically studied.The results show that the Ni ions are successfully doped into the Bi₄O₅I₂ crystal.The specific surface area of the doped Ni²⁺/Bi₄O₅I₂ composite increases from 38.1m²/g to 53.5m²/g,which enhances the adsorption capacity of the target pollutants,and can provide more active sites to participate in photodegradation reactions.Further,the composite photocatalyst was combined with advanced oxidation technology?H₂O₂?,and the Ni²⁺/Bi₄O₅I₂/H₂O₂system degraded hydrochloric-tetracycline?TC-HCl?by more than 90%under visible light for 60 minutes,which was superior to the photocatalytic activity of pure Bi₄O₅I₂and Ni²⁺/Bi₄O₅I₂ and H₂O₂.The excellent catalytic degradation performance of this system is mainly attributed to the effective transfer of photogenerated charge of Ni²⁺/Bi₄O₅I₂ composite under visible light and the synergistic effect of H₂O₂ and photocatalyst.