Preparation of Nano Zinc Tungstate

nano Zinc tungstate image

Nanoscale Zinc tungstate is a high quality photocatalyst with light response, which is usually used as a semiconductor catalyst for the degradation of benzene halides and water pollutants.

High temperature calcinations method (solid phase process), is used for preparing Zinc tungstate in the past, which consumes a lot of energy. Worse still, the particle size of the prepared sample is too large that the specific surface area of the catalyst is greatly reduced, leaving an unsatisfactory photocatalytic efficiency.

In view of the deficiency of solid phase method, liquid phase method has been adopted. There are many kinds of liquid phase methods, such as precipitation, microemulsion, sol-gel and hydro-thermal synthesis, of which the hydrothermal synthesis is an economical and effective method to prepare nano Zinc tungstate.
 
Hydrothermal synthesis is an effective method for synthesis and material treatment, which is carried out in a special closed reactor (such as autoclave). The aqueous solution is used as the reaction system. By heating and pressurizing the reactant, it creates a relatively high temperature and high pressure environment, achieving the dissolve and recrystallization of a substance that is usually insoluble or insoluble.

Some scholars added 0.1452g (0.5mmol) Zinc nitrate (NO (Zn(NO3)2•6H2O) and 1g PVP or mixed surfactants of PVP and SDBS into 40 mL deionized water. And after mixing, sodium tungstate (Na2WO4. 2H2O) of 0.165g (0.5mmol) is added to the solution.

After continually mixing the mixture for 30 minutes to ensure that all the reagents are evenly dispersed, the mixture is added to the 50mL Teflon autoclave. Then adding deionized water until the total volume of the kettle is 80%. Sealing the autoclave, it is time to heat it to 180°C, which will be maintained for 24 hours and then naturally cooled down to room temperature. Collect the white precipitate and wash it several times with deionized water and anhydrous ethanol. Then, nano zinc tungstate was prepared by drying for 6 hours in vacuum at 60°C.

Hydrothermal synthesis has many advantages, such as controllable condition, low cost, mild environment and so on. The method of low temperature solution synthesis has a special effect on the inorganic reaction and the size, morphology, structure and crystallinity of the inorganic photo catalytic material produced thereby.

 

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