Preparation of hydroxyapatite by aqueous precipitation from calcium carbonate and phosphoric acid

Abstract

Abstract Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) is the representative biological mineral which is hard to attain the solution equilibrium and difficult to produce by solution synthesis. HAp finds new application fields to remove harmful elements from polluted wastewater in industrial scales. The low-cost manufacturing process should be developed using abundant available CaCO3 materials. Calcium carbonate (CaCO3), as an economically feasible and abundant precursor, has been used in calcium source for the HAp synthesis. The synthesis was conducted by reacting CaCO3 with phosphoric acid (H3PO4) in aqueous solution with aid of citric acid and sodium hydroxide under moderate synthesis conditions. Compositionally pure HAp has been prepared. The process offered a relatively fast, convenient and economical route for the synthesis of HAp.