Preparation Of Novel Vanadate Heterojunction Materials For Light-driven Antibiotics Removal From Waters

To prevent and treat all kinds of bacteria infection disease,a large number of antibiotics have been continually researched and widely used.However,antibiotic pharmaceuticals played positive role for the prevention and treatment of patients,and they also led to a series of negative influence.The most concerned negative influence of the ecological safety and health risks.However,many antibiotics could easily entere into the environment due to the poor absorption,low metabolism,misuse and overuse.A large number of the parent or metabolites of antibiotic pharmaceuticals were released into the environment.These residues still remnant a certain activity in the environment.Antibiotic residues in environment could cause large amounts of direct toxicities and potential risks.The effects include the development of super bacteria,direct or indirect toxicity to microorganism and possible risks to human beings.Water environment is one of the important places for pollutant release,migration and distribution in the environment.In which various types of pollutants are accepted,and the concentrations of pollutants are often very high.Furthermore,the antibiotic residues constantly detected in water environment as the extensive use and abuse of antibiotic pharmaceuticals,and they are becoming the most concerned emerging pollutants.Antibiotic residues present the characteristics of scattered distribution,widely complicated composition,toxicity,low biodegradability and hard to degradation in the water environment.They are difficult to be removed by traditional processing technology,such as biological treatment,physical treatment and chemical treatment method.In recent years,with the continuous development of the advanced oxidation technologies,semiconductor photocatalytic technology meets a good application prospect in the treatment of the emerging pollutants.However,affected by various factors,the efficiency of semiconductor photocatalytic technology is still remains to be improved.On the one hand,the spectral absorption responsiveness and photon-generated carrier separation ability of the traditional semiconductor catalytic materials are often poor;on the other hand,the antibiotic emerging pollutants and the mechanisms are less attention in the current studies.Based on the antibiotics pollution characteristics and current situation of the development of semiconductor photocatalysis technology,a series novel of BiVO4/FeVO4,FeVO4/Fe2TiO5,BiVO4/Bi2Ti2O7 and BiVO4/NaBiO3 vanadate heterojunction composites have been advised and prepared in this work.The physical and chemical properties of as-prepared samples were characterized based upon XRD,XPS,BET,SEM,EDS,TEM,UV-vis DRS and fluorescence spectrum techniques.These prepared composite samples showed excellent sunlight response characteristics.To evaluate the photocatalytic activity of the novel composites,the removal experiments were carried out by selecting the target pollutants of metronidazole,norfloxacin,tetracycline and sulfadiazine.A novel BiVO4/FeVO4 heterojunction photocatalyst was successfully synthesized by a facile hydrothermal method firstly.The physical and chemical properties of as-prepared samples were characterized using XRD,XPS,BET,SEM,EDS,TEM,UV-vis DRS and fluorescence spectrum techniques.The photodegradation activity of metronidazole(MNZ)was used as a measurement for photocatalytic performance of BiVO4,FeVO4 and BiVO4/FeVO4 heterojunction photocatalyst,which indicated that under visible light irradiation the photocatalytic activity of BiVO4/FeVO4 heterojunction photocatalyst was very effective,and much higher than the pure BiVO4 or pure FeVO4.The possible photocatalytic mechanism was discussed on the basis of the theoretical calculation of the electronic structure,and the experimental results.A new type of FeVO4/Fe2TiO5 composite heterogeneous catalyst was firstly designed and successfully synthesized via a one pot hydrothermal method.The as-prepared FeVO4/Fe2TiO5 exhibited high photocatalytic activity and excellent stability while being used for norfloxacin(NFX)removal from aqueous solution under sunlight irradiation.The high photocatalytic activity may attribute to synergistic effect photogenerated electron-hole with·OH and h+.In the complex photocatalytic degradation process,the piperazine ring within norfloxacin was firstly attacked and ruptured.As the properties of abundant raw material and facile prepared method,FeVO4/Fe2TiO5 composite could be met with a great practical application prospect.A novel flower-like BiVO4 and BiVO4/Bi2Ti2O7 heterojunction photocatalyst was firstly synthesized by surfactant-free hydrothermal route,which is very convenient,rapid,controllable and environmental friendly.The photocatalytic activity of the synthesized novel BiVO4 and BiVO4/Bi2Ti2O7 on the photocatalytic removal of tetracycline(TC)has been performed,revealing that BiVO4/Bi2Ti2O7 composites exhibited superior visible-light driven photocatalytic activitie and recycling abilities.The enhanced photocatalytic activities of BiVO4/Bi2Ti2O7 were either related to the particular structural features or the quality ratios of the BiVO4 and Bi2Ti2O7 in the fabricated heterojunction photocatalysts.The possible photocatalytic mechanism of the prepared BiVO4/Bi2Ti2O7 has been examined by identified photogenerated reactive species based on free radicals trapping experiments.The preliminary removal pathways of tetracycline were proposed on the basis of the identified intermediates using LC-TOF/MS.A novel BiVO4/NaBiO3 composite catalyst was firstly prepared by facile controlled synthesis method,using NaBiO3,Na3VO4 and Bi(NO3)3 aqueous solutions as the raw materials.The systematic composition,structure and optical property characterizations of the as-prepared BiVO4/NaBiO3 conformed the heterojunction has been successfully constructed.The excellent photocatalytic activity and recyclability for sulfadiazine removal over as-prepared BiVO4/NaBiO3 composite samples were demonstrated under xenon light irradiation.The photocatalytic mechanism was discussed based on the reactive species analysis.The removal pathways of sulfadiazine were revealed by determination of intermediates.