Spray drying is a versatile method to perform atomization, drying, and granulation. Spray dryers enable agglomeration of particles into a spherical granule form with a nano-meter size and thus very high specific surface areas (SSA). For this, the synthesized Zn(OH)₂ precipitate should be concurrently atomized and dried under desired spray drying conditions. The drying process has many complex and critical parameters. In order to obtain ZnO nanopowders in a spherical granule form the inlet temperature and the flow rate of the hot air, the feeding rate and the solid-liquid ratio of the suspension, need to be optimized for 150°C ≤ ITHA ≤ 180°C, 5 mL/min ≤ FRS ≤ 15 mL/min, 50 g/L ≤ SLRS ≤ 200 g/L, 0.4 m³/min ≤ FRHA ≤ 0.6 m³/min and 60°C ≤ OTDC ≤ 90°C, respectively. The powders synthesized by these modifications have a range of 5-200 nm (TEM) and high SSA of 21-114 m²·g⁻¹ (average particle size: 9-51 nm according to the SSA analyses) depending on the drying process parameters. The ZnO nanopowders have a soft granule structure according to the SSA analyses. Therefore, there is no need to grind the powders. They can be easily processed at all of the mixing and forming steps. In addition, they do not contain any contamination coming from grinding.

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球形颗粒状ZnO纳米粉的喷雾干燥参数

喷雾干燥是进行雾化，干燥和制粒的通用方法。喷雾干燥器能够将颗粒团聚成具有纳米尺寸的球形颗粒形式，因此具有非常高的比表面积（SSA）。为此，应同时将合成的Zn（OH）₂沉淀物雾化并在所需的喷雾干燥条件下干燥。干燥过程有许多复杂而关键的参数。为了获得球形颗粒形式的ZnO纳米粉，需要在150°C≤ITHA≤180°C的条件下优化入口温度和热空气流速，悬浮液的进料速度和固液比，5 mL / min≤FRS≤15 mL / min，50 g / L≤SLRS≤200 g / L，0.4 m ³ / min≤FRHA≤0.6 m ³/ min和60°C≤OTDC≤90°C。通过这些修饰合成的粉末具有5-200 nm（TEM）的范围和21-114 m ² ·g ^-1的高SSA （根据SSA分析，平均粒径：9-51 nm），具体取决于干燥过程参数。根据SSA分析，ZnO纳米粉具有柔软的颗粒结构。因此，无需研磨粉末。它们可以在所有混合和成型步骤中轻松加工。此外，它们不包含任何来自磨削的污染。