Master Degree / Yüksek Lisans Tezleri

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  • Master Thesis
    Kinetic Morphological, and Compositional Characterization of the Uptake of Aqueous Ba2+, Mn2+, and Cd2+ Ions by Calcite and Aragonite Over a Wide Range of Concentration
    (Izmir Institute of Technology, 2007) Tunusoğlu, Özge; Shahwan, Talal
    The large availability and widespread distribution of calcium carbonate, CaCO3, in Earth.s crust makes it among the most important minerals to investigate in terms of environmentally and geochemically important aqueous-metal partitioning interactions. In this study, the interactions of Ba2+, Mn2+, and Cd2+ with calcite and aragonite were investigated over a wide range of experimental conditions. The experiments were conducted to examine the effects of time, concentration, pH, temperature on the uptake process assess at low concentrations and the composition and morphology of the precipitated carbonates. The kinetic data corresponding to adsorption were adequately described by the pseudo-second order rate equation. At equilibrium, the extent of adsorption on both minerals followed the order Cd2+ > Mn2+ > Ba2+. Precipitation of metal carbonates proceeded at a slower rate and led to large removal of the ions under consideration. The mass fractions of the precipitated metal carbonates were determined using quantitative XRD. For this purpose, empirical equations were developed for binary carbonate mixtures. FTIR was used to follow the possible modifications in vibrational modes of calcite and aragonite, and the newly emerging vibrations of various carbonate phases. According to SEM results, BaCO3 crystals appeared to be 1-2 micrometers in size with an olivary-like shape and MnCO3 crystals assumed a cubic shape with 200-400 nm size. The particles of precipitated CdCO3 did not demonstrate a well defined shape and its texture appeared to be composed of aggregated sub-micron crystals that form micron sized particles with irregular appearance.
  • Master Thesis
    Aas, Xrpd, Sem/Eds, and Ftir Studies of the Effect of Calcite and Magnesite on the Uptake of Pb2+ and Zn2+ Ions by Natural Kaolinite and Clinoptilolite
    (Izmir Institute of Technology, 2005) Zünbül, Banu; Shahwan, Talal; Shahwan, Talal
    In this study, the effect of magnesite and calcite on the uptake of lead and zinc ions by mixtures of these carbonates with kaolinite and clinoptilolite was investigated at various loadings and mixture compositions. The concentration of both ions in the liquid phase was in measured using AAS, while XRPD, SEM/EDS, and FTIR techniques were used in characterizing the solid samples. Thestudy included the determination of kinetics and sorption isotherms of lead and zinc on pure kaolinite and clinoptilolite. Moreover, the sorption behavior of lead and zincat different concentrations and pH conditions was investigated on mixtures of calcite and magnesite with kaolinite and clinoptilolite at carbonate mass percentage compositions of 5, 10, 25, 60 in addition to pure calcite and magnesite. The morphologies of theformed precipitates, the plausible structural change in the lattice of calcite, magnesite, kaolinite, and clinoptilolite originating from sorption of lead and zinc ions was examined. According to obtained results, the sorption affinity of kaolinite and clinoptilolite towards lead is larger than their affinity towards zinc. Within the operating experimental conditions, the sorption capacity increased with increasing the amountsof calcite, and magnesite. The overall order of retention of lead and zinc was observed as magnesite . calcite> clinoptilolite> kaolinite under neutral and alkaline pH conditions and high loadings. When the initialconcentration of zinc and lead ions is raised to saturation conditions, rapid overgrowth of cerussite and hydrozincite was observed. Increasing the initial pH to 10,0 causedenhancement in the dissolution of calcite and magnesite, leading to the enhancingthe precipitation of hydrozincite, and an increased formation of hydrocerussite instead ofcerussite. The uptake of Zn2+ and Pb2+ions by calcite and magnesite have lead to modifying the geometry of the carbonate groups, the thing reflected as variation in their vibrational bands.