Fabrication of layered double hydroxide microspheres by spray drying of nanoparticles: Effects of process conditions

Microspherical agglomerates of nano-sized layered double hydroxide (LDH) particles were prepared using a spray drying technique without addition of dispersant and binder. The effects of process conditions were investigated on the agglomerate size distribution, morphology and specific surface area. The spray-dried agglomerates were spherical in shape, with diameter of 2-15 mu m and with smooth surface without cracks and holes. The agglomerate surface area ranged from 49 to 101 m(2)/g depending on process conditions. The smallest agglomerates with narrowest size distribution were obtained at the highest flow rate of spraying air, while the agglomerates of highest specific surface area were fabricated at the lowest spraying air flow rate. Drying at low temperature and using slurry of low concentration also resulted in formation of small agglomerates. The change in specific surface area was related to the variations in drying rate. Drying at low rate led to the fabrication of agglomerates with high surface area. Thus, by adjusting the spray drying parameters, one could produce LDH microspheres satisfying requirements and utilize them as an intermediate product in the manufacturing of functional materials. (C) 2017 Elsevier B.V. All rights reserved.