The Preparation Of Bismuth Vanadate Photocatalysts And Investigation On Their Inactivation Of Escherichia Coli

In recent years,due to a series of advantages of photocatalytic antibacterial approach,it has been favored by many people.Bismuth vanadate?BiVO₄?is a photocatalyst with excellent visible light response and high catalytic performance.In this thesis,bismuth vanadate?BiVO₄?is used as the target,material to develop photocatalysts by non-metal boron?B?doping,noble metal?Ag?loading and heterojunction with g-C₃N₄,thus improving the catalytic activity.In this thesis,a systematic study on the performance of the above composite catalysts is carried out.The main contents are as follows:1.Boron?B?doped bismuth vanadate?BiVO₄?was synthesized by a simple hydrothermal method.Due to the electron-deficient properties of B element,the recombination probability of electron-holes of BiVO₄ was well reduced.The crystal structure and morphology were studied by XRD,TEM and SEM.The photocatalytic performance of the catalyst was tested by inactivation of E.coli under visible light.Theoretical calculations further prove that B doping can improve the catalytic activity of BiVO₄ and inhibit the recombination of photogenerated electrons and holes.Apparently B doping caused the antibacterial activity of BiVO₄ to change from inert to high activity,and completely inactivated with 1x10⁶ CFU/mL E.coli GB 8099 in the 60 min.2.Bismuth vanadate?BiVO₄?crystals with different crystal phases were successfully prepared by hydrothermal by adjusting pH value.The different ratios of silver-loaded BiVO₄ composite catalysts were successfully prepared by photodeposition.After transient absoption spectroscopy and surface photovoltage test,Ag/tz-BiVO₄ has excellent photocatalytic performance toward E.coli inactivation.The loading of silver nanoparticles can increase the active sites of BiVO₄,further improving separation rate of the holes and electrons.E.coli was inactivated under visible light to evaluate the catalytic performance of the catalyst.The mechanism of E.coli inactivation was further studied by capture experiment,ESR test and quantitative analysis of H₂O₂ fluorescence.3.The composite catalyst g-C₃N₄/BiVO₄ was successfully prepared by a two-step method.After further acidification treatment of g-C₃N₄,the crystal phase is significantly improved after complexing with bismuth vanadate?BiVO₄?.The crystal phase structure and morphology of the composite catalyst were studied by a series of characterization methods such as XRD,TEM and SEM.The antibacterial properties of the catalysts were evaluated by inactivation of E.coli under visible light.Finally,the inactivation mechanism of the composite catalysts inactivated E.coli GB 8099was further studied by capture experiment and ESR test.The experimental results showed that the antibacterial activity of BiVO₄ is significantly improved after doping,loading and modification of the heterojunction structure.