Investigation of the effect of process parameters on nano and micron sized hydroxyapatite production

Control over crystallization is one of the most important techniques in chemical engineering due to its potential to produce well-defined particles with unique structures in the nanometer and micrometer range. In this study, hydroxyapatite (Ca10(PO4)6(OH)2, HAP) crystals were produced via batch and continuous crystallizer (MSMPR ? Mixed Solution Mixed Product Removal) using calcium chloride (CaCl2) and potassium dihydrogen phosphate (KH2PO4) as starting materials. Carboxymethyl inulin (CMI) and latex (acrylic acid polystyrene copolymer) were used as an additive to produce hydroxyapatite (HAP) particles in batch crystallizer under controlled temperature, pH, and atmospheric conditions. The morphology and microstructure of the HAP nanoparticles were investigated by XRD, SEM, FTIR and particle size analyzer. CMI affects morphology, surface area, dimension and particle size distribution of the crystals. The reduction in size is greater in the direction of the c-axis. The SEM micrograph shows the formation of well-crystallized, agglomerated small particles of HAP. X-ray analyses have shown that the resulting particles have high thermal stability. When HAP was precipitated in the presence of latex, the polymer particles become incorporated into the growing crystals, giving polymer?inorganic hybrid materials. Micrometer and submicrometer-sized crystals with a rod like morphology were obtained, depending on the concentration of polymer.In work carried out with MSMPR crystallizer, we investigated the growth and nucleation rate of HAP crystals and the effect of CMI polymer on crystallization. The linear population density model has been used to describe our experimental data. It was observed that the concentration of CMI polymer affects the growth rate of HAP. At the high levels of CMI concentration, it was seen that crystal structure changed needle-shape to spherical-shape particles.