Study On Preparation And Modification Of High-Efficiency Catalyst Materials For Visible Light Catalytic Degradation Of Antibiotic-Tetracycline Hydrochloride

Photocatalytic materials play a vital role in solving environmental problems,especially water pollution.However,most photocatalysts have problems with poor response to visible light and low efficiency of photo-generated electron-hole separation in practical applications.Therefore,in this paper,the energy band structure is controlled by doping,n-n heterojunction,and preparation of new heterogeneous catalysts,so as to broaden the absorption spectrum of the photocatalyst and improve the separation efficiency of the photogenerated electron-hole pairs,thereby improving the photocatalysis degradation efficiency.1.Study on photocatalytic performance of phosphorus-doped self-sensitized carbon nitride microspheres（P-SSCN）The self-sensitized carbon nitride microspheres（SSCN）synthesized by the solvothermal method is oligomeric s-triazine dyes（TBO）which coated on the surface of the SSCN.In the photocatalytic process,TBO will be gradually decomposed as a target degradation product,which leads to the low and fluctuating degradation of tetracycline hydrochloride（TC-HCl）during the early stage of SSCN.Later photocatalytic efficiency increases first and then decreases as the number of TBO decreases.In order to enhance the photocatalytic efficiency of the sample,P-SSCN with different phosphorus doping contents were prepared by a one-step solvothermal method using solid phosphorous acid as the phosphorus source.Through elemental analysis and characterization of the samples,it was found that most of the P elements were doped into the TBO and a small amount was doped into the CN framework.The photocatalytic test of the sample found that P-SSCN has enhanced photocatalytic performance and stability,which may be attributed to the fact that P doping not only reduces the self-degradability of TBO but also changes the bandgap structure,thereby broadening the light response range of SSCN and improving its photocatalytic efficiency and stability.2.Study on photocatalytic performance of hollow hydrangea BiOBr/BiOI n-n heterojunctionUsing Bi（NO₃）3·5H₂O,KBr,BiOI and ethylene glycol as precursors,a Hollow-hydrangea x%BiOBr/BiOI n-n heterojunction was successfully prepared by solvothermal method（x represents the ratio of BiOBr to BiOI,and its value are 2,5,10,15）.TC-HCl was used as the target degradation product to investigate the photocatalytic performance of the samples.The results show that the prepared x%BiOBr/BiOI n-n heterojunction exhibits enhanced photodegradation performance under visible light irradiation.At first,the photocatalytic degradation performance of x%BiOBr/BiOI increased with increasing x,then its photocatalytic degradation performance began to lower when further increasing x.When x=5,the sample5%BiOBr/BiOI has the best photocatalytic degradation ability under visible light,which is 1.3 and 1.6 times than that of BiOI and BiOBr,respectively.This may be due to the existence of the n-n heterojunction in the sample,which promotes the separation of the photogenerated electron-hole pairs under the built-in electric field,thereby improving the photocatalytic degradation ability of the sample.In addition,through capture experiments,it was found that holes（h⁺）and superoxide radicals（?O2^-）were the main active materials in the 5%BiOBr/BiOI photocatalytic degradation of TC-HCl.In addition,the structure and properties of the samples were systematically studied,and the formation mechanism of n-n heterojunctions was discussed accordingly.It is proved that 5%BiOBr/BiOI photocatalytic degradation of TC-HCl is a complete mineralization process,and a possible reaction mechanism is proposed.3.Study on the homogeneous photocatalytic performance of a novel rod-shaped potassium cyanurate（K₃[C₆N₇O₃]）K₃[C₆N₇O₃]was synthesized by heat-treating melon in an oil bath in a strongly alkaline solution.K₃[C₆N₇O₃]was used as a water-soluble cyanurate for the first time as a homogeneous photocatalyst for photodegradation of TC-HCl under visible light.In addition,water-soluble K₃[C₆N₇O₃]has excellent visible-light-driven photocatalytic activity.The ability of photocatalytic degradation of TC-HCl under visible light is 1.3,9,and 10 times that of P25,melon,and g-C₃N₄,respectively.In addition,K₃[C₆N₇O₃]can also be used as a highly efficient heterogeneous photocatalyst to remove TC-HCl from ethanol.This work provides a new type of homogeneous photocatalyst for environmental protection and opens up new fields of application for cyanurate.In summary,the preparation of phosphorus-doped carbon nitride microspheres,the construction of BiOBr/BiOI n-n heterojunctions,and the preparation of new K₃[C₆N₇O₃]homogeneous catalysts provide a practical and feasible method for the modification of photocatalysts for visible-light degradation strategy.