Synthesis of macroporous cristobalite using a hydroxyapatite template

Abstract Macroporous α-cristobalite was successfully synthesized by using a colloid-sized template of cylindrical hydroxyapatite particles that were heat-treated at 1300 °C for 1 hour. The template was easily removed by treating it with hydrochloric acid at room temperature. The macroporous structure was confirmed with a scanning electron microscope. The pore size differed depending on the location; it was mainly 100 nm to 1 μm and larger than 2 μm in some locations. The specific surface area measured by the N 2 -BET method was 3 m 2 /g, which was three times larger than that of ordinary cristobalite. Moreover, the amount of methylene blue dye adsorbed was twice as large as that of ordinary cristobalite.