Preparation of calcium phosphate compounds from by-product of bone gelatin production

Abstract

A by-product from bone gelatin production was used as a starting material for synthesizing calcium phosphate compounds: dicalcium phosphate dihydrate (DCPD), dicalcium phosphate anhydrous (DCPA), monocalcium phosphate monohydrate (MCPM), beta-tricalcium phosphate (beta-TCP), and hydroxyapatite (HA). DCPD was prepared from the precipitation of the starting material solution at various pH values, 4.5-6.0. It was found that the optimum condition for preparing DCPD is to precipitate at pH 5.5. DCPA was also prepared by the same method as DCPD, except that the precipitation was performed at 80 ํC. MCPM was obtained from the evaporation of the synthesized DCPD solution. The preparations of beta-TCP and HA were based on the solid-state reaction of the mixtures of DCPD or DCPA and CaCO[subscript 3] with various Ca/P mole ratios. It was found that pure beta-TCP was obtained from the heat treatment of the DCPD+CaCO[subscript 3] mixture with Ca/P mole ratio = 1.46 at 1100 ํC and HA with high purity was obtained from the heat treatment at 1200 ํC of the DCPA+CaCO[subscript 3] mixture with Ca/P mole ratio = 1.67, or with Ca/P mole ratio = 1.63. The purity of HA obtained could be improved by washing the trace of Ca(OH)[subscript 2] with acetic acid.