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Parameters for spray drying ZnO nanopowders as spherical granules
Author(s) -
Yıldız Ömer,
Soydan Ali Murat
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15191
Subject(s) - spray drying , materials science , granule (geology) , granulation , grinding , porosity , chemical engineering , particle size , grind , nanocrystalline material , volumetric flow rate , freeze drying , chromatography , composite material , nanotechnology , chemistry , engineering , physics , quantum mechanics
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 m 3 /min ≤ FRHA ≤ 0.6 m 3 /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 m 2 ·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.