A Preparation Process of Bismuth Tungstate by Sol-Gel-Hydrothermal Method

Environmental pollution is a major challenge facing by humans today. The use of photocatalytic technology to control environmental problems is one of the most active research fields. Finding high-efficiency photocatalysts is a top priority in this field. Bismuth tungstate (Bi2WO6) photocatalyst is considered to be a potential excellent visible light catalytic material due to its unique electronic structure, excellent visible light absorption capacity and high organic matter degradation ability.

At present, the preparation methods of Bi2WO6 mainly focus on coprecipitation method, sol-gel method and hydrothermal method. The coprecipitation method and the sol-gel method require high-temperature calcination in the preparation process to obtain crystalline Bi2WO6, and the high temperature process directly leads to grain agglomeration and uneven particle size distribution, thereby reducing the photocatalytic performance of Bi2WO6. Hydrothermal preparation of b Bi2WO6 eliminates the high temperature calcination process, and the obtained product has the advantages of crystal integrity and high purity, but the use of this method is not conducive to the composite doping of various elements, and the doping treatment of Bi2WO6 is the most important method to increase its photocatalytic activity.

In response to the above problems, some scholars have proposed a preparation method of Bi2WO6 prepared by sol-gel-hydrothermal method. This method can be doped in the sol-gel process and then hydrothermally reacted. In the prior art method for preparing Bi2WO6, the crystal grains are easily agglomerated and difficult to be doped, and a nanometer Bi2WO6 photocatalyst having a small particle size, a low degree of agglomeration, a complete crystal form and easy doping is prepared. The specific steps are:

1) Prepare 10 ml each of a concentration of 0.024 mol/L lanthanum nitrate solution and a concentration of 0.001 mol/L ammonium tungstate solution. Under stirring, 3.6 ml and 1.8 ml of EDTA with concentration of 0.1mol/l is separately added to the cerium nitrate solution and the ammonium tungstate solution;

2) The above two transparent solutions are uniformly mixed, and then kept in a water bath at 60 ° C for 24 hours to obtain a wet gel, and the wet gel is dried at 110 ° C to obtain a dry gel;

3) The dry gel was transferred to a hydrothermal reaction vessel, 50 ml of deionized water was added, and the pH of the reaction solution was adjusted to 2.0 with nitric acid, and then kept at 220 ° C for 12 hours, and then naturally cooled to room temperature. The obtained product was centrifuged, washed three times with deionized water, and dried under vacuum at 60 ° C to obtain a photocatalyst having high catalytic activity. The X-ray diffraction pattern showed that it was consistent with the crystal structure of barium tungstate. .

The Bi2WO6 photocatalyst obtained by the above method has good crystallinity, the shape is pleated sphere, has large specific surface area and good photocatalytic activity, and overcomes the problem that the crystal grains are easily agglomerated and difficult to be doped in the prior preparation of the Bi2WO6 method. The disadvantages are that a bismuth tungstate photocatalyst with a small particle size, a low degree of agglomeration, a complete crystal form, and an easy doping, and an indium-doped nano-tungstate photocatalyst are prepared.

• < Prev
• Next >