Preparation Of CQDs/b-TiO₂ Photocatalyst And Degradation Of Rhodamine B And Humic Acid

TiO2 has been widely accepted as an environmentally friendly material with superior performance due to its advantages of being environmentally friendly,stable,cheap and easy to obtain,however,the wide band gap of TiO2 limits its further application.Therefore,it is urgent to develop an effective way to overcome this defect and broaden the application range of TiO2.In this paper,CQDs/b-TiO2 nanocones composite catalyst was prepared by hydrothermal method with titanium mesh as substrate.The photocatalytic activity of the catalysts was analyzed by means of material characterization and simulated experiments on the photodegradation of Rhodamine B(RhB)and fulvic acid(FA)wastewater.The main contents of the study are:preparation and characterization of catalysts,simulation and application of catalysts,optimization of operating parameters and mechanism of pollutant degradation.The conclusions are as follows:(1)The TiO2 nanocones prepared by hydrothermal method were modified by reducing and loading carbon quantum dots(CQDs),the experimental parameters were optimized by comparison of characterization and degradation experiments:The optimum temperature for hydrothermal synthesis is 180 ℃,the reaction time is 24 h,the dosage of urea is 1.8 g,and the temperature of calcination is 400℃,the TiO2 nanocones synthesized under these conditions are uniformly distributed and have larger specific surface area.The optimal reduction temperature is 80℃,the time is 4 h and the NaBH4 is 0.2 mol/L.The optimum temperature for CQDs loading is 120℃,reaction time is 4 h,and dosage is 1 mg.(2)The photocatalytic activity of each sample was studied by photodegradation of RhB and FA simulated wastewater.The experimental results show that the photocatalytic performance of CQDs/b-TiO2 nanocones composite catalyst is better than other samples,and the sample can remove 100%of RhB and 93%of FA within 40 min and 120 min,respectively.Through the cycle experiment,it is proved that CQDs/b-TiO2 nanocones composite catalyst has stable photocatalytic activity and high recycling ability.(3)The effects of ·OH,·O2-and h+on photodegradation of RhB and FA were studied by capturing agent experiments.It was found that·O2-and h+played a major role in photodegradation of RhB and FA(4)The effect of dissolved oxygen and reaction mechanism during photodegradation were studied by adding aeration device and combining with capturing agent.It is proved that Ti3+and CQDs can collaborate to enhance the O2 adsorption capacity of the catalyst,which can improve the effective utilization of electrons and holes and the catalytic activity.the rate of degradation was increased by 6 times.