Experimental Study On The Photocatalytic Removal Of Tetracycline By TiO₂ Composites

In recent years,the biological inhibition and resistance genes of antibiotic wastewater have attracted wide attention.TiO₂ is a non-toxic and harmless catalyst with low price.TiO₂ photocatalytic technology can effectively remove antibiotics from wastewater,but its photocatalytic performance still has great space for improvement.In this paper,tetrabutyl titanate as titanium source,combining coprecipitation method with sol-gel method,TiO₂、Fe₃O₄-TiO₂ and Fe₃O₄-TiO₂-C₆0 photocatalyst powder are prepared to explore the optimum photocatalytic reaction conditions for the degradation of tetracycline.They are analyzed by XRD、XPS、BET、SEM/HRTEM and other characterization methods.The photocatalytic results show that,the optimum doping amount Fe₃O₄ in Fe₃O₄-TiO₂ is 60 mg and the optimum doping amount of C₆0 in Fe₃O₄-TiO₂-C₆0 is 5 mg.The optimum calcination temperature is 400 ℃,best p H is 7 and best dosing is 70 mg.Under these conditions,TiO₂ 、 Fe₃O₄-TiO₂ 、 Fe₃O₄-TiO₂-C₆0 degradation of 50 m L tetracycline solution of 20 mg/L at 24 min can reach 65.84 %、92.51 %、95.25 %.The characterization analysis shows that,TiO₂、Fe₃O₄-TiO₂ and Fe₃O₄-TiO₂-C₆0 are anatase phases,The Fe in the composites are mainly in the form of Fe₃O₄,C mainly exists as sp² hybrid carbon and O-C=O,indicating Fe₃O₄、C₆0 and TiO₂ recombination success.The average particle sizes are 11.6 nm、10.6 nm、10.4 nm,the specific surface areas are 82 m2/g 、 114m2/g 、 116m2/g,and the pore sizes are among 2¹0 nm.Respectively,the small particle size shortens the transfer time of photogenerated carriers and the large specific surface area increases the reaction sites for degrading pollutants,which improves the photocatalytic activity.According to quenching experiment,the main reactive substance of Fe₃O₄-TiO₂、Fe₃O₄-TiO₂-C₆0 in the photocatalytic degradation of tetracycline system is h VB+.The change of tetracycline removal rate is kept within 5% after repeated use for 5 times.With the combination of experiment and characterization,the photocatalytic activity of the composites are enhanced mainly because the decrease of particle size shortened the diffusion time of photogenerated carriers to the catalyst surface,and the increase of specific surface area increase the contact surface with pollutants,and Fe₃O₄、C₆0 addition inhibits the recombination of photogenerated carriers and improves the quantum efficiency of light.Fe₃O₄、C₆0 and TiO₂ recombination can effectively improve the photocatalytic activity of TiO₂.