The threonine effect on calcium phosphate preparation from a solution containing Ca/P=1.33 molar ratio

In this study, calcium phosphate materials were prepared by a modified precipitation method using high-speed dispersing equipment. A solution with a Ca/P molar ratio of 1.33 (octacalcium phosphate stoichiometry) was transferred into the reactor vessel with different concentrations of threonine at temperature 97 degrees C. A white precipitant was collected after the addition of condensed ammonium solution and the samples were subsequently calcined at 900 degrees C. From the XRD patterns and FT-IR spectra of the uncalcined samples, three phases of octacalcium phosphate (OCP), monetite (DCP) and hydroxyapatite (HA) were obtained. Calcined samples showed two phases of P-tricalcium phosphate (beta-TCP) and calcium pyrophosphate (CPP). SEM micrographs showed the different morphology of samples. The specific surface areas (ssa) were 45-53 m(2)/g for and 5-6 m(2)/g for calcined samples. From the obtained results, we found that threonine added in various amounts in the initial solution inhibits the formation of HA and consequently creates OCP and DCP. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.