Porous hydroxyapatite monoliths from gypsum waste

Abstract

Porous hydroxyapatite (HAp) monoliths were synthesized from gypsum mold waste with diammonium hydrogen phosphate solution by hydrothermal treatment at 50-190°C and their properties studied. Gypsum waste samples could be completely converted to HAp with 0.5 mol dm –3 (NH 4 ) 2 HPO 4 at 50°C in 15 days and 100°C in 2 days. This paper describes the effect of hydrothermal reaction conditions such as reaction temperature, time and concentration of (NH 4 ) 2 HPO 4 on the formation of new HAp monoliths and their porous properties.