Effect of Adsorption of Succinic Acid on the Formation of Amorphous Calcium Phosphate

Abstract

Adsorption of dissolved succinic acid on the formation of ACP and its stability were investigated in the synthetic process of ACP by the reaction of CaCl2-(NH4)2 HPO4-C4H6O4-NH4OH. The crystallization of ACP to HAp and amount of succinic acid adsorbed were affected by some conditions such as initial pH, temperature, aging time and concentration of succinic acid in the mother liquor. The largest amount of succinic acid was adsorbed to ACP when the ACP was produced at 0°C, initial pH 10 and concentration of succinic acid 6.0 mass% and aged at 25°C for 3h. From the result of infrared spectra of the ACP which adsorbed succinic acid, two peaks due to carboxylic acid were newly found at 1400cm-1 and 1550cm-1. These peaks were not found from the result for a mixture of ACP and succinic acid. The adsorbed succinic acid was decomposed at about 480°C and ACP was crystallized to Ca3(PO4)2 at above 600°C by heating.