Master Degree / Yüksek Lisans Tezleri

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  • Master Thesis
    Characteristics of Limes Produced From Marbles and Limestiones
    (Izmir Institute of Technology, 2007) Toprak, Gülcan; Böke, Hasan; Böke, Hasan; 02.01. Department of Conservation and Restoration of Cultural Heritage; 02. Faculty of Architecture; 01. Izmir Institute of Technology
    In this study, characteristics of lime produced from some marbles and limestones were investigated in order to compare their effects on the lime mortars. For this purpose, limestones that contain low and high amounts of diatoms and marbles quarried from the city of Muğla and the Marmara island were selected as samples. The calcination temperatures of the stones were found to be around 800 C by TGA analysis. Considering their calcination temperatures, they were heated to 850 C in a laboratory furnace, then slaked and carbonated. Before and after these processes, mineralogical and chemical compositions, and microstructures of the products were investigated by XRD and SEM-EDS analysis. The hydraulic properties of carbonated limes were evaluated by determining weight loss at the temperatures between 200-600 C due to the loss of the structurally bound water of hydraulic products and weight loss at the temperatures over 600 C due to carbon dioxide released during the decomposition of calcium carbonates by TGA. The effects of limes on the properties of mortars were investigated by producing lime mortars and comparing their compressive strengths during one year carbonation in laboratory condition. Mortars were prepared with one part (in weight) of lime and three parts (in weight) of marble aggregates. The results of the study indicated that the lime produced from limestone containing high amounts of diatoms is highly hydraulic due to formation of calcium silicate whereas the others are non-hydraulic. The mortars prepared from lime containing high amounts of diatoms were found to be relatively high in compressive strength due to its hydraulicity. The results show that the production of hydaulic lime composed mainly of calcium silicate at a relatively low calcinations temperature (850 C) is possible. Considering this result, it can be concluded that hydraulic lime could be produced by the calcining of limestone containing diatoms in historic kilns.
  • Master Thesis
    Biodiesel Production From Safflower Using Heterogeneous Cao Based Catalysts
    (Izmir Institute of Technology, 2012) Yalman, Emir; Şeker, Erol; Şeker, Erol; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In this study, the activities of heterogeneous mixed oxide catalyst; calcium oxide on alumina was investigated in the transesterification of canola and safflower vegetable oils to produce biodiesel, i.e. methyl esters. The primary goal of this study is to understand the effect of calcination temperature and calcium oxide (CaO) loading on the conversion activity of calcium oxide on alumina in the transesterification of canola and safflower vegetable oils. The mixed oxide catalyst was prepared by a modified single step sol-gel method. Calcium oxide was chosen because of its well known basic property. This study shows that calcium oxide on alumina catalysts having high CaO dispersion, calcined at high temperature, gave high biodiesel yields even under the reaction conditions, such as low reaction temperature, 50 °C, 9 of methanol/Oil molar ratio, 6 wt. % of catalyst/oil, and also short biodiesel reaction time, such as 4 – 10 minutes in the transesterification of safflower and canola oils. Also, it was observed that 70% CaO/Al2O3 catalyst when calcined at 700 °C was the most active catalyst among all the catalysts prepared in this study. Moreover, the reusability of CaO/Al2O3 demonstrated that ~20 – 250 ppm of Ca was lost during the reaction and the amount of Ca cation leaching depended on the reaction time, CaO loading and the calcination temperature. Also, it was found that Ca cation loss occurred during the reaction did not hinder the activity of the catalysts, which was found by the reusing the catalysts for couple times. Besides, when the biodiesel yield was higher than 70%, the system was influenced by external mass transfer limitation.