Preparation Of Spherical Calcium Carbonate And Its Application To Hydroxyapatite

Calcium carbonate is one of the common inorganic minerals in nature.It has been widely used in papermaking、coating、rubber、printing ink、medicine and other departments.Calcium carbonate with different morphology with different application fields,spherical calcium carbonate has high surface area,good permeability,so the study of functional calcium carbonate products with special morphology and size can have become a research hotspot in the field of materials.In this paper,by a precipitation method,PVP is used as a shape control additive for the preparation of spherical calcium carbonate,the reactant concentration,the concentration of PVP,reaction temperature,reaction mixing mode,stirring speed and other effects of synthesis conditions on the properties of the product,the conditions for synthesizing spherical calcium carbonate were optimized.As a probe,PVP was added 1 g/L,the reaction temperature is 40℃,the concentration of the reaction system was 0.4 mol/L,stirring speed at 500 rpm,and the rapid mixing method,the spherical calcium carbonate particle size is 1-2μm and the uniform size is dispersive.The method has good reproducibility and has certain guiding significance for industrial production.The concentration of polymer PVP plays an important role in the preparation of spherical calcium carbonate.The concentration is too high and too low,which is not conducive to the formation of uniform spherical calcium carbonate.As a morphology control agent,PVP has an important influence on the morphology and crystal shape of the prepared calcium carbonate,and has little influence on the particle size of the product.By PSS morphology control agent,to explore in the dosage of PSS was f%,the reaction temperature is 35 °C,the concentration of the reaction system was 0.4 mol/L,and the rapid mixing method,the spherical calcium carbonate particle size is 5 μm and the uniform size is dispersive.The study found that the different amount of reactant concentration and reaction temperature and the reaction products of PSS have great influence on particle size and morphology.The concentration of the reactants is bigger,the product size is smaller,the higher the temperature,the surface of spherical calcium carbonate is more rough,and the reaction time has little effect on the product morphology.Spherical calcium carbonate is prepared by PVP,which can be used as a template to prepare a spherical mesoporous hydroxyapatite,exploring the three key factors of hydrothermal synthesis for preparing hydroxyapatite,namely hydrothermal reaction time,reaction concentration,reaction pH,by experiment,determined to hydrothermal time at 24 h,the concentration of the reactant at 0.1 mol/L,under the conditions of the pH=12 reaction conditions,The prepared spherical mesoporous hydroxyapatite can maintain a stable morphology of calcium carbonate,and the remaining calcium carbonate is relatively small.The prepared mesoporous hydroxyapatite has a specific surface area and a well-developed mesoporous structure,it is about 51.56 m~2/g,with an average pore size of 11.32 nm and a pore volume is 11.27 cm~3/g.Selection of hydroxyapatite on the sodium salicylate load,the results show that the prepared hydroxyapatite can effectively load and release of sodium salicylate,hydroxyapatite particle size is smaller,the larger specific surface area,load quantity of sodium salicylate is also bigger.In the release,the HAP particle size is small,drug release process is slow,to achieve the release balance needed for longer periods of time,this is due to the smaller particle size,The smaller the pore size is,the greater the resistance of the release,the release ratedecreased gradually.