Preparation Of Bi Based-photocatalyst And Photocatalytic Degradation Of Tetracycline Wastewater Under Visible Light Illumination

Escalating environmental pollution and energy crisis lead to a growing demand for technologies of environmental restoration and energy conversion.These demands can be solved by photocatalysis,which is an increasingly developed photochemical technology.Bi-based photocatalysts are promising candidates driven by visible light,which can be used for repairing the environment and convert energy.Bi-based photocatalysts have attracted much attention from researchers due to their high visible light photocatalytic activity.In this paper,several Bi-based photocatalysts were prepared by different synthetic methods,and the phase composition,morphology and optical absorption characteristics of the samples were characterized and analyzed by X-ray diffraction,scanning electron microscopy,Fourier transformed infrared spectra and UV-visible diffuse absorption spectroscopy.The photocatalytic activity of the prepared samples were evaluated by degrading tetracycline hydrochloride?TCH?in visible light,and the photocatalytic degradation mechanism was proposed.The specific contents of this paper are as follows:?1?The monoclinic phase Eu/BiVO₄ photocatalyst was synthesized through one-step hydrothermal synthesis.In the process of photocatalytic degradation of TCH,1%Eu/BiVO₄ showed the best photocatalytic performance,and the photocatalytic efficiency during 150min reached 91.4%.In addition,the stability of 1%Eu/BiVO₄was studied by the cyclic degradation experiment,and radical trapping experiment revealed that the order of the influences of active species on photocatalysis is h⁺>·O₂^->·OH.?2?Bismuth-rich bismuth oxybromide was prepared via mixed solvothermal route.By adjusting the ratio of ethylene glycol to water and the reaction temperature,it was found that the photocatalytic effect of Bi₂₄O₃₁Br₁₀0 prepared under 35mL of ethylene glycol at 120?was the best.The degradation efficiency of TCH in 40min was 91.1%.The cyclic degradation test showed that the sample had good stability.The radical trapping experiment revealed that h⁺is the main active species in the process of photocatalytic degradation.?3?The effects of additives and microwave power on photocatalytic properties of bismuth bromide oxide were investigated by microwave method.In the process of photocatalytic degradation,the photocatalytic activity of Bi₂₄O₃₁Br₁₀0 which was obtained by adding ethylenediamine at 400W was the best,and the degradation efficiency of TCH in 60min was 91.2%.The sample had good stablity during the photocatalytic process.It was found that h⁺was the main active substance in the radical capture test.?4?The effects of ammonia water dosage and reactant concentration on photocatalytic properties of bismuth iodide were investigated by hydrolysis method.In the photocatalytic performance test,the degradation efficiency of Bi₄O₅I₂synthesized under the conditions of 1mL ammonia and 3mmol reactant concentration reached 91.0%after visible light irradiation with TCH for 20min.The stability of Bi₄O₅I₂ was demonstrated by cyclic degradation experiments and radical trapping experiment showed that h⁺is the main active species in the process of photocatalytic degradation.?5?Bismuth iodide was prepared by mixed solvent thermal method.The effect of the ratio of ethylene glycol to methanol on the photocatalytic properties of the product was investigated.It was found that the photocatalytic efficiency of Bi₄O₅I₂prepared by 20mL ethylene glycol and 20mL methanol mixed solvents system reached 91.0%after 40min by visible light irradiation.In addition,it was also found in the experiment that changing the type of unitary alcohol would affect the photocatalytic performance of Bi₄O₅I₂,and the degradation effect was BOI-IS>BOI-ET>BOI-ME>BOI-H₂O in order.Besides,the sample was stable during the photocatalytic reaction process.Radical trapping experiment showed that the order of active species'effect on photocatalysis was h⁺>·O₂^->·OH.