Preparation Of Bi₂MoO₆ Based-photocatalyst And Photocatalytic Degradation Of Antibiotics Under Visible Light Illumination

In the 20th century,the discovery of antibiotics has brought mankind to a new stage in the fight against disease.With the extensive use of antibiotics,the discharge of antibiotic wastewater has increased.However,the traditional sewage treatment technology cannot achieve the effective removal of antibiotics.Therefore,the safety of the ecological environment may be seriously endangered if antibiotic wastewaters are discharged at will.In recent years,photocatalysis is widely used for the elimination of antibiotics due to its advantages such as energy saving and environmental protection,non-toxic and so on.Bi₂MoO₆ is a novel visible-light catalyst which has been attracted considerable attention for its unique physical and chemical properties.However,the low quantum efficiency limits its application prospects in photocatalysis.The methods,such as the constrution of heterogeneous phase junction,doping non-metallic ion and self-defect,were used to modify Bi₂MoO₆ for enhancing its photocatalytic activity by improving the utilization efficiency of photogenerated carriers.Three antibiotics?Ciprofloxacin,Tetracycline and Oxytetracycline hydrochloride?were used to evaluate the catalytic activity of catalysts.The main research contents are as following:1.A series of binary-phase TiO₂?Anatase and Rutile?modified Bi₂MoO₆ crystals with multicomponent heterojunction were prepared by solvothermal-calcination method.Heterojunction formed at the interface between TiO₂ and Bi₂MoO₆,which largely boosted the effective separation of photocarriers at TiO₂/Bi₂MoO₆ heterojunction interface,and the efficiency of photocarriers utilization was improved.Thus,the TiO₂/Bi₂MoO₆ composites displayed superior photocatalytic activity for the removal of the three antibiotics under visible-light irradiation.The heterojunction combining with optimal TiO₂ content?0.41 wt%?exhibited the highest photocatalytic activity.In particular,the removal rate of ciprofloxacin over TiO₂?0.41 wt%?/Bi₂MoO₆ was 33%higher than that of pure Bi₂MoO₆.2.A serious of I_y-Bi₂MoO₆ catalysts were prepared by doping non-metallic iodine ions.After doping iodine,the specific surface area of Bi₂MoO₆ was obviously increased,and the adsorption ability of antibiotics was increased.In addition,doping iodine into Bi₂MoO₆ lattice became the center of carrier capture,which largely boosted the effective separation of photocarriers and the efficiency of photocarriers utilization.Thus,I_y-Bi₂MoO₆ catalysts presented outstanding photocatalytic activity for the removal of the three antibiotics under visible-light illumination.I_0.4-Bi₂MoO₆ exhibited the highest photocatalytic activity,and the subscript means the molar ratio of I to Mo is 0.4.In particular,the removal rate of ciprofloxacin over I_0.4-Bi₂MoO₆ was 37%higher than that of pure Bi₂MoO₆.3.The oxygen vacancy?OV?concentration-tunable Bi₂MoO₆ was developed via a facile low-cost solvothermal approach with assistance of glyoxal reductant by solvethermal method.The optical absorption extended and the band gap narrowed with the oxygen vacancies introduced.Oxygen vacancies not only render appearance of defect band level in the forbidden band,but also can result in valence band maximum and conduction band minimum up-shift.Then it promoted the redox performance of photocatalysts.Therefore,OV-BMO displayed excellent photocatalytic performance in contrast to Bi₂MoO₆.Among these obtained samples,2-OVBMO prepared by adding reduction solvent glyoxal of 2 mL exhibited the highest photocatalytic activity.In particular,the removal rate of ciprofloxacin over2-OVBMO catalyst was 59.6%higher than that of pure Bi₂MoO₆.The above studies indicated that the construction of heterogeneous phase structure,doping non-metallic ions and self-defect regulation are effective means to improve the photocatalytic performance of Bi₂MoO₆ and enhance the quantum efficiency of Bi₂MoO₆.