Mineralization kinetics of sparingly soluble calcium-salts: A constant composition and dual constant composition study

摘要

The mineralization mechanism of sparingly soluble Ca-salts is of considerable interest due to its widespread applicability to industry and medicine. In the present work the Constant Composition, CC, and Dual Constant Composition, DCC, methods have been used to investigate the mineralization of calcite, hydroxyapatite, HAP, and fluoroapatite, FAP. Calcite mineralization was investigated in the presence of polyacrylic acids, PAA and polyvinylsulfonate/polyacrylic acid copolymers, PVS/PAA (TCA = TCO$sb3$ = 1.985 mM, I.S. = 0.15 M, pH = 8.5, T = 25$spcirc$C). Particle size distribution as well as electrophoretic mobility measurements were performed to study the effect of the additives on the calcite surface. All of the additives inhibited calcite growth with PAA being more effective than PVS/PAA. This was probably due to the higher concentration of carboxylate groups in the former. The DCC method was utilized to study FAP/HAP simultaneous mineralization (pH = 6.5-7.4, I.S. = 0.15 M, TCA = 1.35-0.4 mM, TPO$sb4$ = 0.81-0.24 mM, TF = 0.25-1.0 ppm). The reaction solids were analyzed by wet chemical methods, $sp{19}$F MAS NMR, FEM/SEM and XRD. The influence of Zn$sp{2+}$ on these processes was also investigated.