Preparation Of MIL-53（Fe） By Microwave And Its Photocatalytic Performance

At present,it is still very challenging to develop novel,environmentally friendly and highly stable photocatalysts with low cost to utilize solar energy to deal with environmental pollution.The traditional photocatalysts have a low utilization rate of solar energy and can not meet people’s demand for photocatalysts.Metal-Organic Frameworks（MOFs）have shown potential application prospect in photocatalysis and other fields due to the characteristics that MOFs exhibits semiconducting properties and highly designability,enable us to moderate porous,topological structures and surface properties easily.Therefore,it is of great significance to explore an efficient and convenient method to prepare MOFs materials with high catalytic activity.In this dissertation,we aimed to research the influence of modified preparation method on porous,topological structures and surface properties of MIL-53（Fe）materials.Meanwhile,we investigated the relationship between the structure and property of MIL-53（Fe）in the field of photocatalysis.1.MIL-53（Fe）was prepared by single-mode focused microwave method and surfactant-assisted synthesis method.The surfactant included tetraethylammonium hydroxide（TEAOH）,cetyltrimethylammonium bromide（CTAB）and polyoxyethylene-polyoxypropylene-polyoxyethylene（P123）.It was found that MIL-53（Fe）/P123 has the best photocatalytic performance,under the best microwave reaction conditions of 100℃,75 W,1.5 h,and the best ratio n（Fe Cl₃·6H₂O）:n（P123）=1:0.3,the degradation rate of Rhodamine B reached 94%.Under p H=3,the degradation rate reached97%.Compared with MIL-53（Fe）,its specific surface area and pore volume have increased from 136.8 m~2/g and 0.282 cm~3/g to 222.7 m~2/g and 0.524cm~3/g.The degree of opening was increased,the reset rate of photo-generated electrons and holes was inhibited,and the absorbing ability was enhanced.2.The photocatalytic degradation of Rhodamine B showed that the degradation rate of MIL-53（Fe）modified with surfactant P123 and CTAB to100 m L of 10 mg/L Rhodamine B can reach more than 90%in 100 minutes.The photocatalytic degradation of Rhodamine B showed that the photocatalytic activity of MIL-53（Fe）/P123 or MIL-53（Fe）/CTAB was superior to MIL-53（Fe）,while the photocatalytic activity of MIL-53（Fe）/TEAOH was inferior to MIL-53（Fe）,its degradation rate was only41%.Through the experiment of free radical capture,it can be seen that the holes and（·OH）are the main contributors to the photocatalytic process.3.The degradation rates of MIL-53（Fe）/P123,MIL-53（Fe）/CTAB and MIL-53（Fe）/TEAOH prepared by solvothermal method to Rhodamine B were 65%,71%,20%,while the degradation rates of corresponding samples prepared by microwave method were increased to 94%,91%and 41%,respectively.Compared with the solvothermal method,the microwave method shows higher photocatalytic activity.Moreover,the microwave method has absolute advantages in terms of simple operation,rapid reaction and low energy consumption,which has potential significance for large-scale preparation of MOFs materials and has a broad application prospect.