Supported Bismuth Tungstate Photocatalyst

Photocatalytic degradation of environmental pollutants has attracted increasing attention due to its outstanding advantages such as low energy consumption, mild reaction conditions, easy operation, and reduced secondary pollution. Bismuth tungstate is a new type of visible light catalyst. Its band gap is small, its light absorption ability is strong, and it is easy to modify. It is becoming the main product of photocatalyst.

The main method of preparation of bismuth tungstate photocatalyst is hydrothermal synthesis, and many bismuth tungstate composite photocatalysts are also completed by hydrothermal method. Although the existing bismuth tungstate photocatalyst can better solve the problem of visible light excitation, its photocatalytic activity needs to be improved. Therefore, synthesis is the main way to improve the photocatalytic properties.

A preparation scheme of supported bismuth tungstate photocatalyst has been published by some scholars. It can overcome the defects of light photocatalytic activity existing in bismuth tungstate photocatalyst, and its main process is as follows:

1.At 15 to 25 degrees, bismuth nitrate [Bi (NO₃) ₃· 5H₂O], sodium tungstate [Na₂WO₄·2H₂O], alkyl quaternary ammonium salt, C1 to C4 aliphatic monools, ammonia and water were mixed evenly in the reaction to get the mixture.

2.When the temperature is between 15 and 25 degrees, we add orthosilicate ester to the mixture obtained by step (1) and stir it for at least 4 hours. After filtration, the obtained solid is washed and dried in turn.

3.Calcined at 500 ℃ ~ 550 ℃ for 4-6 hours, to obtain a supported tungstic acid photocatalyst.

After the above process, bismuth tungstate was successfully loaded on the silicon oxide mesoporous molecular sieve MCM-48, and the mesoporous structure of MCM-48 could be maintained. It has been proved that the photocatalytic activity of supported bismuth tungstate photocatalyst is higher than that of the existing bismuth tungstate photocatalyst. Moreover, the raw materials of the catalyst are easy to obtain, and the preparation conditions are mild, and other elements can be further added to modify the composite.

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