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The soft template regulation of calcium carbonate crystal growth studies

Author: YuanZongWei
Tutor: XieAnJian
School: Anhui University
Course: Inorganic Chemistry
Keywords: Soft-template Calcium Carbonate Biomineralization Crystal Growth
CLC: O782
Type: Master's thesis
Year: 2004
Downloads: 294
Quote: 4
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Abstract


Using templates is an important method to regulate and control the morphology and size of crystal. According to the characterization of templates and the ability of their domain limitation, template methods were divided into two parts, hard-template methods and soft-template methods. Soft-template methods mainly included many kinds ordered congeries that composed by amphiphathic molecules, such as liquid crystal, colloid, microemulsion, vesicle, LB films, self-assemble films, and so on, the self-assemble structure of macromolecules and biomacromolecules was also included. Soft-templates have particular characterizations. First, they have absolute advantage in simulating the progress of biomineralization since they were composed mainly by amphiphathic molecules; second, the shape of soft-templates were versatile; third, soft-templates were easy to construct and complex equipments were not needed. Though soft-templates were not always controlled the crystal morphology and size strictly, they draw people’s attention by their characterization mentioned above.In the dissertation, different soft-templates were used to regulate and control the growth progress of calcium carbonate under present conditions in our lab. Versatile morphologies and different polymorph of calcium carbonate were produced in our experiences, and the mechanisms of these results were investigated. The main information is followed.1. A new kind of Amino-Carboxyl-Chelating-Agent(ACCA), 1,2-bis(4-amino phenoxy)ethane-N,N-N’,N’-tetraacetic acid(4-BAPTA) was synthesized and characterized by Fourier transform infrared spectroscopy, 1H- nuclear magnetic resonance and elements analysis, and its property was also studied. Experimental result indicated that this compound has a strong chelating ability to Ca2+, and the fluorescence intensity of this compound was increased with the increase of Ca2+ concentration under suitable conditions. This compound was expected to be a new kind calcium fluorescent indicator.2. The aqueous solution of 4-BAPTA was used as an effective soft-template toregulate and control the crystallization of CaCO3. The important parameters, namely the pH of solution, the concentration of 4-BAPTA and the supersaturation of CaCCO3, were systematically studied. Spherical vaterite and calcite with various morphologies were produced in the presence of 4-BAPTA by simply constant precipitation method. The results indicate that the BAPTA has effect not only on the polymorph but also on their morphology and size of CaCO3 crystals.3. The mixed solution of 4-BAPTA and CTAB was used as an effective soft-template to regulate and control the crystallization of CaCO3.(1) The surface properties of mixed solution of 4-BAPTA and CTAB were investigated. The TEM and DLS showed that 4-BAPTA and CTAB have combined to form stably vesicles, and the mechanism of vesicle’ forming was also discussed.(2) Based on the investigation of properties of mixed system, the influence of mixed system to growth of calcium carbonate was investigated and explained. The results indicated that vaterite crystals have been induced by vesicle system.4. The magnesium ions, L-Cystine, Tyrosine, DL-Aspartic Acid, L-Lysine, and the mixed system of magnesium ions and amino acid were used as effective soft-templates to regulate and control the crystallization of CaCCb, respectively.(1) The effects of magnesium ions to growth of calcium carbonate were investigated under different molar rate of magnesium ions to calcium ions, and the mechanism of effect was also discussed. The result indicated that with the molar rate of magnesium ions to calcium ions increased, the ability of magnesium ions to induced aragonite was enhanced, and when the molar rate reached to 8.0, the products would be aragonite only.(2) L-Cystine, Tyrosine, DL-Aspartic Acid, L-Lysine were used as soft-templates to regulate and control the crystallization of CaCO3. The effects of different amino acid to the growth of CaCO3

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CLC: > Mathematical sciences and chemical > Crystallography > Crystal growth > Crystal growth process
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