Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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  • Article
    Rice-Like, Hollow, and Rhombohedral Nano-Calcite Synthesis by Carbonization
    (Elsevier, 2026) Kilic, Sevgi; Toprak, Gorkem; Ozdemir, Ekrem
    Controlling the morphology and size of calcium carbonate (CaCO3) remains an essential challenge in the production of high-performance fillers and advanced functional materials. Here, we report a continuous carbonization strategy that enables the synthesis of monodisperse nano-calcite particles with tunable rice-like, hollow, and rhombohedral morphologies through precise control of CO2 dissolution into a flowing Ca(OH)2 solution under diffusion-limited conditions. A two-stage reactor was designed to decouple nucleation and growth by separating the gas-liquid interaction zone from a stabilization tank. pH and conductivity analyses revealed that crystallization is primarily governed by the CO2 dissolution kinetics rather than mixing intensity in the stabilization tank. SEM and XRD analyses demonstrate a distinct crystallization sequence such that initial formation of rice-like calcite, subsequent development of hollow nanoparticles through selective tip dissolution, and final transformation into rhombohedral calcite via dissolution-reprecipitation mechanism. The method provides a reproducible, template-free route for fabricating hollow CaCO3 nanoparticles, overcoming limitations of bubbletemplating and additive-mediated techniques. This scalable process provides a robust foundation for producing high-surface-area CaCO3 nanomaterials which have potential applications in thin films, ceramics, protective coatings, lightweight composites, thermal/acoustic insulation, adsorption, and catalysis, where tailored particle morphology and size can significantly enhance performance.
  • Article
    Citation - WoS: 48
    Citation - Scopus: 52
    Stability of Caco3 in Ca(oh)2 Solution
    (Elsevier Ltd., 2016) Kılıç, Sevgi; Toprak, Görkem; Özdemir, Ekrem
    The effect of calcium hydroxide (Ca(OH)2) on the stability of calcium carbonate (CaCO3) particles was investigated with respect to the surface potential and particle size. Both CaCO3 and Ca(OH)2 were dissolved in ultrapure water at concentrations up to 100 mM. The solubility limits were about 18 mM for Ca(OH)2 and about 0.13 mM for CaCO3 at 23 °C in water. Dissolution of commercial CaCO3 in 10 mM of Ca(OH)2 solution and dissolution of Ca(OH)2 in 10 mM of CaCO3 slurry were also studied at similar conditions. Conductivity, pH, zeta potential, and average particle sizes were measured for each solution. The morphological characteristics of the particles were analyzed by the SEM images. It was found that the zeta potential of CaCO3 particles was greater than + 30 mV when they were placed in the Ca(OH)2 solution compared to a zeta potential value of - 10 mV in water. It was concluded that the Ca(OH)2 solution is a stabilizer for the CaCO3 particles.
  • Article
    Citation - WoS: 20
    Citation - Scopus: 23
    Rice-Like Hollow Nano-Caco3 Synthesis
    (Elsevier Ltd., 2016) Ülkeryıldız, Eda; Kılıç, Sevgi; Özdemir, Ekrem
    We have shown that Ca(OH)2 solution is a natural stabilizer for CaCO3 particles. We designed a CO2 bubbling crystallization reactor to produce nano-CaCO3 particles in homogenous size distribution without aggregation. In the experimental set-up, the crystallization region was separated from the stabilization region. The produced nanoparticles were removed from the crystallization region into the stabilization region before aggregation or crystal growth. It was shown that rice-like hollow nano-CaCO3 particles in about 250 nm in size were produced with almost monodispersed size distribution. The particles started to dissolve through their edges as CO2 bubbles were injected, which opened-up the pores inside the particles. At the late stages of crystallization, the open pores were closed as a result of dissolution-recrystallization of the newly synthesized CaCO3 particles. These particles were stable in Ca(OH)2 solution and no aggregation was detected. The present methodology can be used in drug encapsulation into inorganic CaCO3 particles for cancer treatment with some modifications.