| Strontium carbonate (SrCO3) is one of the basic chemical reagents, and it has been widely used in the producing of glass for color television tubes, ferrite magnets for small DC motors and fluorescence materials etc. Superfine SrCO3with high purity is one of basic material in modern manufacturing electronic units and has bright use potential. Ionic liquids (ILs) has been regarded as one of green solvents and been used in chemical reaction, separation process and nanomaterials preparation. The main goals of this article is to use ILs as template agents and reaction media to synthesis nanostructure SrCO3with different morphology and try to explain the mechanism of how ILs effect the nucleation kinetics when prepare nanostructure SrCO3in ILs. The performances of the different morphology nanostructure SrCO3have also been investigated. The main results are as follow.(1) By used the different ILs, we successfully prepared nano SrCO3with special morphology such as nanowhisker, nanospindle, nanorod, seaflower-like aggregate etc. and it is found that SrCO3synthesis in ILs with special task groups [HOEmim]NTf2gain smaller particle; different concentration of [C4mim]PF6can modulate suitable reaction environment, and it lead the auto assembling nano SrCO3with special morphology. When [C4mim]Cl was taken into account as reaction media, by recording the morphology of SrCO3in different time interval using SEM techniques, we propose the model of "nucleus-nanospindle-rodlike-flower bundles aggregate-seaflower aggregate" morphology evolution. The different morphology nano SrCO3shows good UV-Vis absorption phenomena, and the smaller particle, the stronger UV-Vis absorption it revealed.(2) In ILs-methanol bi-system, nano SrCO3with special morphology such as nanowhisker, nanospindle, ellipsoidal, sphere aggregate, nanosphere, rodlike aggregate, etc. have been obtained. The as-synthesized product show good uniformity and monodisperse, the diameter of nanosphere is about80nm. Methanol can enhance the solubility of Sr(OH)2in the system, and the morphology and uniformity of nano SrCO3obtained better than that obtained in ILs-water system. However, when the higher reaction temperature was presented the smaller diameter of the product it has. Different diameters of nano SrCO3show different initial decomposing temperature. The smaller grain and the rougher surface, the lower decomposing temperature it has. The experimental results indicate that nanosphere and nanowhisker showed the lowest decomposition temperature of938℃, and the irregular shape SrCO3showed the decomposition temperature as high as1000℃(3) In water-methanol system, nano SrCO3with dumbbell like, ellipsoidal and high length to diameter ratio of rodlike have been obtained. Nanometer SrCO3crystal prepared in pure methanol shows low crystallinity, low reaction temperature is beneficial to the formation of the porous structure. FTIR analysis show that the hydrogen bond was found in the product indicate the methanol’s absorption can low down the surface free energy of strontium carbonate crystal nucleus, thereby change the morphology of SrCO3, N2isothermal adsorption-desorption analysis showed that the dumbbell strontium carbonate surface area is14.9m2·-g-1, and its pore size distribution is range from12nm to32nm.(4)By using solvothermal method, nanostructure of SrCO3with morphology of flower-like aggregate, nanorod, hexahedral ellipsoids, nanosphere, hollow microsphere etc. has been obtained. Study results revealed that hydrophobic ionic liquids can affect SrCO3morphology by microemulsion while hydrophilic ionic liquids can change the crystal morphology by absorbing certain crystal plane. The higher the solvothermal temperature, the smaller grain size the product it has; by prolong the solvothermal time, the strontium carbonate crystal development more completely. By studying the fluorescence properties of SrCO3:1%Eu3+with different morphology synthesis in ILs, it is found that under325nm light excitation, the spectra of the luminous intensity central around614nm and it belongs to red light region, which is due to the electron transition of5D0-7F2. The order of the intensity of fluorescence prepared from three different morphology of strontium carbonate is:flowerlike aggregate> nanosphere> hollow microsphere.(5) By using the technology of scanning electron microscope (SEM) and atomic absorption spectrophotometer (AAS), we studied the effect of the present of [Cgmim] Br to the nucleation kinetics in Sr (OH)2-CO2-H2O carbonation system. With a starting concentration of cSr(OH)20=0.1mol·dm-3, the relationship between the heterogeneity nucleation rate J and time reveals that in the starting period of nucleation, nucleation took place rapidly, the Sr(OH)2in the system were mainly supplied the nucleation of SrCO3crystallization, and the nucleation speed decreased as the crystallization proceeding. Higher concentration [C8mim]Br resulted in lower carbonation speed. At20s after reaction, the present of72.7mmol [C8min]Br can reach a nucleation rate of84.9×1017number·m-3·s-1and a growth speed of0.63nm·s-1. High concentration [C8mim]Br can speed up the nucleation rate. The presented of [C8mim]Br can promote the heterogeneity nucleation. |
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