Formation of Hollow Solid Microparticles during Interaction of Gas with the Substance Present in Solution Microdroplets Transported by Air Flow

The hollow spherical microparticles are formed on mixing of two air flows of microdroplets of solutions of substances A and B (the substance B is readily transported from solution to gas phase) which react to yield a solid substance C, as found by scanning electron microscopy; air flows are obtained using ultrasonic generators. Outer diameter of the hollow microparticles formed is close to that of the microdroplets of the initial solution. The hollow microparticles of hydrazone are obtained by the interaction of droplets of hydrazide solution and formaldehyde entering into gas phase from microdroplets of its acidic aqueous solution. In addition, the hollow microparticles of iron hydroxycholide were obtained by the reaction of FeCl₃ aqueous solution and ammonia entering into gas phase from the microdroplets of its solution. The hollow microparticles presumably of cobalt hydroxynitrate were obtained by the reaction of microdroplets of Co(NO₃)₂ aqueous solution and ammonia. The outer diameter of the hollow particles obtained is equal to 3–10 m, and wall thickness to 2–2.5 m.