| Nowadays,China is still the most populous country in the world,which determines the huge demand for water resources in China.However,the increasingly serious water pollution at home will not only lead to shortage of water resources,but also may seriously threaten people's normal drinking water safety and health.How to solve water quality problems in an environmentally-friendly and efficient manner has become a top priority.Traditional sewage treatment methods such as biological and physical methods have many disadvantages such as high requirements for reaction conditions,long treatment cycles,and easy to cause secondary pollution.Therefore,photocatalysis,which can directly and effectively use sunlight to treat pollutants,stands out as a green and energy-saving photochemical catalysis.Among many semiconductor photocatalytic materials,TiO2 has become one of the most promising materials at present owe to its stable properties,non-toxicity and low cost.But,the shortcomings of wide band gap and low photon utilization of TiO2 have greatly limited its practical application.In this paper,we modified TiO2 from three aspects:morphology control,semiconductor coupling and metal and non-metal element doping.The morphology,structure,and optical properties of the titanium dioxide-based composites were characterized by analysis methods such as XRD,FT-IR,SEM,BET,and UV-vis.The photocatalytic property was tested using rhodamine B(RhB)and methyl orange(MO)as target pollutants.The main research contents are as follows(1)Through single-factor experiments,different samples were prepared by hydrothermal synthesis.The effects of hydrothermal temperature,hydrothermal time,reaction system pH,calcination temperature and the amount of sodium dodecylbenzenesulfonate(SDBS)on the photocatalytic activity of TiO2 were investigated by means of single factor experiment,according to the photocatalytic degradation rate of RhB.The results showed that the optimum conditions were hydrothermal temperature of 120?,hydrothermal time of 6 h,and pH of 1 and the added SDBS was its first critical micelle concentration.The mesoporous TiO2 prepared under this condition was used to degrade 50 mg/L rhodamine solution with the fastest degradation rate.It can reach 100%when exposed to visible light for 1 h,even if it was reused for 5 times,the degradation rate is still above 90%(2)g-C3N4/TiO2 and Cu2O/TiO2 heterojunction composite photocatalysts were successfully prepared by deposition and solvent reduction methods,respectively.The analysis showed that the absorption range of these two materials for light was expanded,and the separation of photo-generated electron-hole pair was more effective.Under visible light,MO was used as the target pollutant,and the photocatalytic performance of different composites were investigated.20%g-C3N4/TiO2 exhibited the highest photocatalytic efficiency with a rate constant of 0.0467 min-1,which was 20 times that of commercial P25.The photocatalytic performance of 6-Cu2O/TiO2 was better than other samples in the same series,but unfortunately,its degradation effect on MO was much lower than that of the monomer TiO2.(3)GR/TiO2 and Cu/TiO2 doped composite photocatalysts were successfully prepared by hydrothermal method.The characterization results showed that neither GR nor Cu doping would change the crystal phase structure of the anatase TiO2,but reduced the interface charge transfer resistance.Under visible light,both 10-GR/TiO2 and 5-Cu/TiO2 could improve the photocatalytic degradation efficiency of MO.Moreover,the latter had better performance,its rate constant was 0.0193 min-1,and the degradation rate of MO could reach 97.6%after being exposed to light for 3h. |
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