Preparation of hollow spheres structured of spherical arrangement of fine particles (component particles) has been reported. The preparation process includes adhesion of component particles onto oil droplets in an aqueous solution and precipitation of binder between the component particles. In this study, quartz hollow spheres with Ni(OH)2 were prepared using ammoniac alkaline Ni(NO3)2 solution as starting solution for binder. The hollow spheres in this system were obtained with much higher efficiency compared to those reported previously by the authors using CaCO3 binder. Formation mechanism of quartz hollow spheres with Ni(OH)2 binder was discussed. It was confirmed that adsorbed cationic species (Ni (II) complex, most likely) should play an important role through the whole process. In order to avoid wasteful precipitation of binder in bulk solution, the following conditions would be required for the precipitation behavior: 1) nucleation should occur preferentially on component particles; 2) the supersaturation should decrease sufficiently within the stage 1), so that growth of precipitate on component particles rather than nucleation in bulk solution be enhanced; 3) the low supersaturation of the stage 2) should not be raised until completion of the precipitation.
ASJC Scopus subject areas
- Chemical Engineering(all)