Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Production of Nano Calcite in Large Scale(Izmir Institute of Technology, 2013) Alıcı, Sezen Duygu; Özdemir, EkremCalcium carbonate (CaCO3) has been used extensively as filling material in various industries in order to improve some mechanical properties of the composite materials and to reduce the product costs. There are mainly two methods for synthesizing CaCO3 crystals: chemical method and carbonization method. The carbonization method is the most appropriate method for nano calcite production. A systematic study was conducted on the synthesis of calcite in nano sizes, homogeneous size distribution, and different morphologies by employing the newly developed small penetration method. The effects of various parameters on the particle size and morphologies such as flow rates of raw materials, concentration, pipe diameter, volumes of stabilization tank and reaction chamber, length in the reaction chamber, stirring rate, and temperature were investigated. Calcite particles of about 100-150 nm were achieved to produce in homogeneous size distributions for the developed method at large scale.Master Thesis Nano calcite (CaCO3) production in semi-batch bubble reactor(Izmir Institute of Technology, 2013) Ülkeryıldız, Eda; Özdemir, EkremCalcium carbonate (CaCO3) has been widely used as filling material in many industries due to its low cost and enhancement in some of the physical properties of the composite materials. The main purpose of this study was to produce CaCO3 particles by carbonation method in nano size, homogeneous size distribution and different morphologies. A semi-batch bubble reactor was designed in order to introduce carbon dioxide (CO2) into the Ca(OH)2 solution or its slurry with a controlled fashion. Different parameters such as stirring rate, Ca(OH)2 concentration, CO2 flow rate, and pulse CO2 injection were examined. Also, jet flow was applied in the stirred tank reactor to prevent particles from aggregation. Conductivity and pH values of solutions were monitored during crystallization. Zeta potential values and average particle size were measured instantly by dynamic light scattering (DLS). Particles produced were separated by centrifugation, dried at 105 oC in an oven for 1 day, and characterized by the Scanning Electron Microscopy (SEM) for their morphology, and X-Ray diffraction (XRD) for their crystal structures. On the basis of XRD analysis, the main crystal form of precipitated particles was calcite. According to SEM images, elongated chain-like, cubical, and rectangular particles were achieved to be produced with particle size of about 200 nm to 400 nm.Master Thesis Effect of Reaction Conditions and Organic Additives on the Morphologies of Synthetic Calcium Carbonates(Izmir Institute of Technology, 2006) Altay, Esra; Shahwan, TalalIn this study, the effects of experimental conditions on the facile morphosynthesis of CaCO3 were investigated. The analyzed conditions included the pH, concentration, mixing and aging temperature, and aging time. After establishing the optimal conditions for calcite and aragonite formation, the effects of organic additives, i.e., PVP, PDDA, PEG, CTAB and EDTA, on the stability and morphology of both polymorphs were examined. Finally, the applicability of calcite as a filling material in polyester was tested. The results indicated that calcite was optimally synthesized at pH 9.0, 0.05 M initial reactant concentration, and 30oC mixing and aging temperatures while the aging time was 24h. The morphologies of produced calcites were dominated by rhombohedra and cubic with particle size range of 5-6 m. On the other hand, the precipitation of CaCO3 dominated with aragonite requires mixing and aging temperatures of 70-90 in addition to shorter aging times. Within such experimental condition, aragonites displayed needle-like and branch-like morphologies with ca. 95% aragonite fraction and aspect ratio of around 8. The applied additives demonstrated various effects on the morphology of precipitated CaCO3. These effects ranged from changing the particle morphology of calcite and aragonite up to suppression of aragonite formation. Finally the application of calcite as a filler in polyester polymer is discussed in light of a comparative determination of mechanical and thermal properties.