Nano grain size tungstic acid may be synthesized by chemical precipitation method using ammonium metatungstate (AMT) and hydrochloric acid (HCL) as raw materials, and the agglomeration of nanoparticles may be effectively improved with the addition of ethanol. And nano tungstic acid with high purity, small particle size and good dispersion may be prepared by liquid phase precipitation method in the alcohol-water system.
Synthesis of Monodisperse Tungstic Acid Nanoparticles by UV Irradiation
Monodisperse tungstic acid nanoparticles with an average particle size of about 20nm may be prepared by radiating an aqueous solution of citric acid tungsten citrate complex with ultraviolet light. And it was studied to found that:
1. Monodisperse tungstic acid nanoparticles consist of WO3•2H2O and WO3•H2O.
2. The citric acid tungsten citrate complex decomposes under ultraviolet irradiation to form citric acid and tungstic acid, and citric acid undergoes photodegradation under the catalysis of tungstic acid.
3. The effect of illumination time, the ratio of amount of citric acid and sodium tungstate substances (ncit/nst) on the structure and morphology of the product:
With the extension of illumination time, the content of WO3•2H2O in the product decreased while the content of WO3•2H2O increased. The particle size of the product increased and the distribution broadened.
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