Preparation and Mechanism of Calcium Carbonate Whiskers from DoLOMITE Refined Solution

The preparation of calcium carbonate whiskers by gas-liquid contact method using low-grade dolomite refining solution and CO2 as raw materials has attracted widespread attention. The effects of reaction temperature, Mg2+ concentration and pH value on the morphology, particle size, aspect ratio and crystal form of CaCO3(Calcium carbonate? whiskers are investigated in detail. SEM (Scanning Electron Microscope) and XRD (X-ray powder diffraction) are combined to analyze the calcium carbonate whiskers. The results demonstrated that under the conditions such as 100 degrees C, Mg2+ concentration of 0.05 mol L-1 and pH value of 9.5, calcium carbonate whiskers with uniform distribution, aspect ratio of 15-20, and purity of 99.38% can be prepared. Through Material Studios simulation software and critical nucleation energy analysis, it is confirmed that the morphology of calcium carbonate whiskers emerged to be a long hexagonal prism. Mg2+ in the refined solution would adhere to the surface of calcium carbonate during carbonization, inhibit the formation of calcite phase, and promote the growth of face clusters connected by vertex angles between CaCO3 crystals. The initial pH condition determines the solubility of CO32- and the supersaturation of the solution, which in turn affected the formed calcium carbonate crystal form. The SEM image in the above figure shows that the calcium carbonate whisker is a long hexagonal prism octahedron structure, and the Morphology module of Materials Studio simulation software predicts that the growth of (111) (221) (112) crystal plane tends to be hexagonal prisms, and the growth morphology of (021), (012), (041) and (130) crystal plane is long rhombohedral columnar whiskers. This shows that the morphology of calcium carbonate whiskers is consistent with the predicted structure of Materials Studio simulation software, which makes it more reliable to judge the morphology of calcium carbonate whiskers by the diffraction peak intensity of each crystal plane of XRD pattern. image