Processing of porous ceramic spheres by pseudo-double-emulsion method

A process for the fabrication of porous ceramic spheres for microorganism carriers is described. A new fabrication method for the process was developed using simple gelcasting and bubble-in-water-in-oil type of pseudo-double-emulsion. The globules, consisting of a foamed mullite suspension, were dispersed and consolidated in spherical shape in liquid paraffin as gelation progressed. The green spheres were pyrolysed at 600 °C and sintered at 1500 °C. The influence of surfactants, extension ratio, and impeller revolution rate on the process and characteristics of the spheres was investigated. The sphere size was in the range 1–5 mm and determined directed by impeller revolution rate. The macropore size in the case of the anionic surfactant was less than that for the cationic surfactant. The inner macropores were interconnected and extended to the external surface. The macroporosity of macropores, in the range 65–79%, increased with extension ratio.