New progress in preparation and application of ultrafine zinc oxide

The preparation methods of zinc oxide are divided into three categories: direct method (also known as American method), indirect method (also known as French method) and wet chemical method. The direct method uses zinc oxide ore as raw material, reduces the zinc oxide in it to vapor-phase zinc, and then oxidizes and reshapes it to obtain products. The production cost is low, but the product quality is not high, especially the content of low melting point impurities is relatively high. The indirect method of zinc oxide uses zinc ingots as raw materials. The zinc vapor is oxidized in air to obtain zinc oxide. The product quality is good, but the cost is high and the total power consumption is large. The wet chemical method can use various zinc-containing materials as raw materials, adopt acid leaching, alkali leaching or pressure leaching to extract zinc, then precipitation to obtain zinc carbonate, and finally to roast to obtain zinc oxide. Most of the ultrafine zinc oxide currently on the market is produced from wet chemical processes and indirect methods.

The spray pyrolysis method uses zinc acetate or nitrate solution atomization to evaporate the liquid, and further decompose it in a dispersed state to obtain zinc oxide. Transmission electron microscope observation of ZnO powder obtained by ultrasonic spray pyrolysis of zinc acetate methanol solution with different concentrations showed that as the concentration of the solution increased, the powder obtained was finer. It can be seen that in spray pyrolysis, ultrasonic spray is beneficial to reduce the particle size and distribution of the powder, and methanol solution is more conducive to obtaining ZnO powder with small particle size and narrow distribution than aqueous solution.