Nano Binary Molybdenum Tungsten Composite Oxide by Hydrothermal Method Preparation

Transition metal oxides can be used in various fields. Molybdenum oxide and tungsten oxide, as two important transition metal oxides, have attracted the attention of scholars and experts in the fields of photocatalysis and gas sensors for a long time. In the past few years, it has been found that the properties of binary molybdenum tungsten oxide (MoxW₁-xO₃) materials can be greatly improved due to the "synergistic effect" of the two elements. Therefore, by changing the composition and structure of materials, we can make this "synergistic effect" play a stronger role.

At present, the preparation methods of nano binary molybdenum tungsten composite oxide mainly include sol gel method, precipitation method, molten salt roasting method, hydrothermal method and so on. The product prepared by hydrothermal method has the advantages of uniform particle size, small size, difficult agglomeration of particles, simple method and low cost. The preparation process by hydrothermal method includes:

1.27 g ammonium molybdate tetrahydrate and 0.65 g sodium tungstate were dispersed in 80 mL water, added hydrochloric acid with a concentration of 7.5 M at 14 mL, and then the reaction system was stirred by ultrasound at 60 ~℃ for 90 minutes; the precipitation obtained by ultrasonic stirring was washed three times with deionized water, and the precipitation was dispersed in 60 mL water; 0.6 g p-nitrobenzoic acid was added and stirred for 30 minutes. The system was transferred to tetrafluoroethylene kettle gallbladder and heated at 170 ℃ for 36 h. After cooling, the system was washed three times with centrifugal water and then washed with absolute ethanol. The product was dried at 70 ~℃ for 5 hours to obtain binary molybdenum-tungsten composite oxide powder.

By controlling the amount of reactant, reaction time, reaction temperature and morphology of protective agent, the uniform morphology of binary molybdenum tungsten nanocomposite oxides was successfully obtained, and the adsorption performance of dye MB was improved. In the experiment of adsorbing methylene blue, 15 mg binary molybdenum-tungsten composite oxide adsorbent was added into 50 mL, 10 mg L^-1 methylene blue solution. After adsorbing for 1 h, the dye removal rate could reach 99%, showing excellent adsorption performance.

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