| Water resources are one of the important resources for human survival.With the continuous development of industrial science and technology,water pollution has becoming more and more serious.The production of antibiotics and the use of antibiotics in China are both large,which leads to the serious problem of antibiotic pollution in China,the pollution of antibiotics has became one of the environmental problems in China.At present,the treatment methods of antibiotics in industry have some disadvantages,such as low efficiency,high energy consumption and high possibility of secondary pollution.In this paper,a degradation method named photo-Fenton was used to degrade antibiotic wastewater under visible light by prepared suitable photocatalysts and designed corresponding photocatalyst devices.This paper is divided into three parts:Part 1 Synthesis and Study of TiO2 Doped with Metal and Nonmetallic Elements in Different Transition ZonesAnatase TiO2 doped with Mn,Fe,Cu,and Zn was prepared by hydrothermal method.The Characterization results of XRD,UV/Vis et.al showed that the doped TiO2 still retained anatase phase.Fe doped TiO2 and Mn doped TiO2 had high visible light response,and their bandwidths were 1.61 eV and 0.64 eV,respectively.However,iin the experiment of degradation of metronidazole wastewater,it was found that the degradation efficiency of Mn doped TiO2 was very low,while that of Fe doped titanium dioxide was about 80%.N,S,Si and Fe codoped TiO2 were prepared,and a series of characterizations were carried out.It was found that Fe/Si codoped TiO2 had highest visible light response,better stability,higher specific surface area and highest degradation efficiency,and the degradation efficiency of metronidazole wastewater was 93%.Part 2 The Degradation Mechanism and Process Conditions of Degradation of Metronidazole by Fe/Si codoped TiO2.In this chapter,the characterization results of HTEM,XPS and BET showed that Fe/Si codoping greatly increased the specific surface area of the catalyst(pure TiO2 and Fe/Si codoped TiO2 were 54.134 and 296.069 m2/g,respectively).At the same time,the doping of Si improved the stability of the catalyst and reduced the metal ion spillover in the catalyst.The mechanism of metronidazole degraded by Fe/Si codoped TiO2 was studied.It showed that the active substances were determined to be h+and·OH.And the degradation products of metronidazole were determined by HPLC-MS.Finally,the process conditions for degradation of metronidazole were optimized by response surface methodology.Optimum condition:Concentration of MNZ:6.0 ppm;pH:7.0;irradiation time:50 min;catalyst dosage:0.3 g/300 mL;dosage of H2O2:0.1 ml(concentration of H2O2,10.0 M)Part 3 The Synthesis of ATP-Fe/Si Codoped TiO2 and a Design of Photocatalytic Device.In this chapter,we synthesized ATP-Fe/Si codoped TiO2 before/after reaction and designed an all-weather photocatalytic degradation device.The catalysts were characterized by SEM,XRD and UV/Vis.It was found that the supported catalyst successfully adhered to ATP rod-like structure and retained the anatase phase structure with the highest catalytic efficiency.At the same time,it had good visible light response,better stability,higher specific surface area,smaller band gap(1.49 eV)higher degradation rate(85%)and good suspension dispersibility in water environment(p=0.6107 g/cm3).The all-weather photocatalytic degradation device has the following characteristics:high hydraulic retention time,energy conservation,convenience and rapidity,which were very helpful for the practical application of photocatalytic degradation. |
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