Preparation of Diopside-Rich Compounds Using Rice Husks and Their Phosphorus Recovery Capability.

Rice husks, wastes from rice production, are expected to be useful as a phosphorus recovery material. While rice husks could be used for phosphorus recovery as they are, there is potential to increase their phosphorus recovery capacity by diopside conversion. This is because diopside is one of the silica-based biomaterials that has the characteristic of precipitating calcium phosphate from aqueous solutions containing phosphorus, such as body fluids. In this study, diopside was synthesized by immersing Aichi no Kaori rice husks in a Ca-Mg aqueous solution followed by calcination. The diopside content of resulting compound was 12%. Phosphorus recovery by the diopside-containing compound was confirmed. Given the diopside content in the compound, it was considered possible that components other than diopside might also be contributing to the phosphorous recovery.