Morphology Control And Application Of Calcium Carbonate Particles

Different morphology of calcium carbonate particles with different properties and application fields,so it is particularly important to control the morphology of calcium carbonate Based on the traditional polymer control agents,this paper has investigated the morphology control of calcium carbonate by selected the unconventional inorganic control agents and built the new calcium chloride ethanol solution reaction system.At the same time,some factors affecting the morphology and the mechanism of calcium carbonate were studied for finding the appropriate reaction conditions used to prepare the specific morphology of calcium carbonate.Further,the application performance of different morphology of calcium carbonate in different field was investigated.By a large number of experiments to obtain some results,the main research contents and results are as follows1.The effect of AlCl₃ on the crystal morphology of calcium carbonate was investigated.Al Cl₃ together with Ca Cl2 served as mixed calcium ion sources and sodium carbonate as carbonate ion sources,calcium carbonate crystals were prepared and the morphology was effected by double decomposition method in the solution with the complex net-shaped aluminum hydroxide gel produced by Al³⁺double hydrolysis.The obtained samples were characterized by Raman Spectrometer,X-Ray Diffraction（XRD）and Field Emission Scanning Electron Microscope（FESEM）.The result indicates that aluminum chloride had a significant effect on the reaction process and morphology.When the addition of aluminum chloride increased,the molar ratio of calcium and aluminum ions increased gradually,the morphology of calcium carbonate becomes sphere,flower and spindle.All phases are vaterite and the change of the system concentration has no effect on the crystal phases of products,but the average particle size increases slightly with the decrease of the concentration.The temperature is the main factor affecting the crystal phase,the aragonte was easily synthesized in high temperature and the vaterite was easily synthesized in low temperature.2.The new calcium chloride ethanol solution reaction system was built and the effects of the new reaction system on the crystal morphology of calcium carbonate was studied.The effect of different carbonate ions sources,different concentration conditions and reaction environment on the morphology of calcium carbonate was investigated by using the calcium chloride ethanol complex solution as special calcium ions source.The obtained samples were characterized by Transmission Electron Microscope（TEM）,X-Ray Diffraction（XRD）and Field Emission Scanning Electron Microscope（FESEM）.The result indicates that the spherical calcium carbonate particles with a multi-stage hollow structure were obtained by the reaction with ammonium carbonate and calcium chloride ethanol solution at the room temperature and low concentration.The rhombic calcium carbonate particles were obtained by the reaction with ammonium bicarbonate and calcium chloride solution and the special pumpkin-liked calcium carbonate particles were obtained by the reaction with sodium carbonate and calcium chloride solution.3.The application performance of three typical morphology of needle-rod,rhombic and spherical calcium carbonate particles on the starch adhesive and drug loading and sustained-release fields was investigated.The samples were characterized by Thermogravimetric Analysis（TGA）,X-Ray Diffraction（XRD）and Field Emission Scanning Electron Microscope（FESEM）and so on.The result indicates that the rhombic calcium carbonate particles possess the best application performance in the starch adhesive.When the amount of rhombic calcium carbonate was 3%（based on the adhesive mass）,both the shear strength in dry state and wet state reach the maximum with the value of 7.23 MPa and 3.83 MPa;In the aspirin loading and sustained-release field,the absorbance was measured by UV-Vis spectrophotometer and the standard curve and in vitro release curve were established.Then the spherical calcium carbonate particles possess the maximum loading with the value of 183 mg/g and the best sustained-release performance by calculated this absorbance and curves.