The Alkaline Fusion-Hydrothermal Synthesis of Hydroxyapatite-Zeolite (HAP-ZE) from Blast Furnace Slag (BFS): Effects of Reaction Temperature

This study was performed to investigate the effects of reaction temperature on the alkaline fusion-hydrothermal preparation of hydroxyapatite-zeolite (HAP-ZE) using blast furnace slag (BFS) as raw material. Firstly, HAP-ZE samples were obtained under various reaction temperatures; then the analysis was carried out utilizing XRD, FT-IR, BET/BJH, XRF, FE-SEM and EDX. The results reflect that the optimum reaction temperature for preparing HAP-ZE from blast furnace slag (BFS) using alkaline fusion-hydrothermal treatment is around 100 °C. The HAP-ZE synthesized at 100 °C had the largest specific surface area (SSA) value. Under 100 °C aging, the main phases in HAP-ZE were zeolite and HAP with the average SSA is 44.22 m2·g−1. Molar ratio of Ca/P, Si/Al and Na/Al is 1.61, 1.31, 1.75, respectively. Additionally, HAP-ZE crystals with a diameter of about 500 nm form an open frame structure with coral surface morphology could be clearly observed at 100 °C. The observed surface morphology feature agrees well with that for HAP-ZE previously reported, again elucidating the successful formation of HAP-ZE.