| CIP is a synthetic third generation fluoroquinolone antibiotic,mainly used forurinary tract infections,sexually transmitted diseases and skin infections.Most of fluoroquinolone antibiotics in the body can’t be completely metabolized,It will be excreted as a metabolite and eventually flow into the sewage treatment plant as the sewage flows.Antibiotics flowing into the environment with sewage can enhance bacterial resistance and harm the human body,such as it can reduce human immune ability which can reduce people’s resistance to disease.Therefore,such antibiotics will cripple humans and ecology.In recent years,composite semiconductor catalysts have attracted many researchers’s attention because of their ability to degrade toxic and harmful gases,low energy consumption and high efficiency.Among these semiconductor photocatalysts,TiO2 has become one of the most widely used due to its low toxicity,strong oxidation ability,easy to synthesize,low cost and stable physical and chemical properties.This article main research content is that we get nano-TiO2 material by using hydroxypropyl cellulose as a dispersant and calcining in a muffle furnace.Methylene blue was used as a target pollutant,the material performance was studied by transmission electron microscope,scanning electron microscope,energy spectrometer,X-ray diffraction and analysis of visible light photocatalytic degradation experiment.the research content and results in the article are as follows:1.The performance of unmodified nano-TiO2 materials were studied by TEM,XRD and photocatalytic degradation experiments,the degradation rate of methylene blue could reach more than 95%in 3 hours for both the materials prepared by standing and stirring.In comparison,the photocatalytic rate and effect of the materials prepared by stirring were better than those prepared by standing.At the same time,the content of tetra-n-butyl titanate(TBOT)with different ratios(0.30,0.85,1.50 mL)was used to synthesize the nano-TiO2 material,and its characterization by TEM showed that the material containing 0.85 mL TBOT had more uniform diameter,better dispersion and more spherical shape than the other two kinds of particles.2.In order to improve the photodegradation performance of the above materials,the nano-TiO2 material was modified.The modified nano-TiO2 material was studied by TEM,SEM,XRD,EDS,energy spectrum analysis and photocatalytic degradation experiment,and the modified material was more dispersed than the sample before modification,its surface was more rough,and its nitrogen content increased significantly.At the same time,XRD and photocatalytic degradation experiments confirmed that the optimal temperature for calcining was 500℃,because the materials calcined at 500℃ had more anatase and rutile types,and its photocatalytic performance was better than that of single anatase.The optimal N/Ti ratio was determined to be 1:1.Nano-TiO2 material had better performance at this ratio.Within 3 h,the nano-TiO2’s scatalytic efficiency of methylene blue reached more than 95%,while when the N/Ti ratio was 1:2,the degradation efficiency could only reached 60%.3.According to the actual application,the antibiotic ciprofloxacin was used as target pollutant,the nano-TiO2 materials were synthesised at best ratio to conduct the photocatalytic degradation experiment,we studied different effect on photocatalytic performance due to different dosage of nano-TiO2,different pH of ciprofloxacin.The nano-TiO2 has significant degradation effects to ciprofloxacin,the degradation rate of ciprofloxacin reaches 95%within 2 h.The best optimal dosage of nano-TiO2 is 400 mg/L.Reaction conditions on the pH value of 7.5 is the best.By XRD characterization,the crystal shape and structure of nano-TiO2 material remained basically unchanged before and after the application.Through the recycling experiment,although the activity of the catalyst will decrease with the increase of the number of use,the degradation rate of ciprofloxacin still can reach 60%after three times.At the same time,we established the kinetic model,and the fitting curve showed that it basically conforms to the apparent first-order kinetic equation.The catalytic oxidation reaction rate constant was calculated as 0.0217/min,and the correlation coefficient R2 was calculated as 0.9516. |
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