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    Effect of selenium incorporation on the structure and in vitro bioactivity of 45S5 bioglass
    (Springer, 2020) Karakuzu-lkizler, Burcu; Terzioğlu, Pınar; Oduncu-Tekerek, Bilge Sema; Yucel, Sevil
    In vitro bioactivity, biodegradation, and biocompatibility behavior of a new bioactive glass systems were investigated with the incorporation of selenium oxide, for the replacement of sodium oxide in the traditional 45S5 bioglass composition. The apatite-forming ability of melt-derived bioactive glasses was evaluated by immersion studies in simulated body fluid while monitoring the concentration of silicon, calcium, phosphorus, sodium, and selenium in the medium. The weight loss of bioactive glasses and pH change in the tris-(hydroxymethyl)-amino methane buffer solution was determined to observe the biodegradation behavior of glass samples. The glasses were characterized by a Fourier transform infrared spectroscopy, scanning electron microscopy, inductively coupled plasma, and Vickers hardness measurements. The biocompatibility evaluation of the glasses was determined through in vitro osteogenesis assays by cell viability, alkaline phosphatase activity, and mineralized matrix formation. The incorporation of selenium enhanced the hydroxyapatite formation on the bioactive glass surface and microhardness of glasses. The hardness of glasses was found to decrease with immersion duration. The results indicate that selenium incorporated bioactive glasses can be used as bioactive material in bone tissue engineering applications.
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    Mesoporous silica aerogels for sunflower oil refining and investigation of their adsorption performance
    (Springer, 2025) Soylu, Tulay Merve; Ozel, Cem; Ikizler, Burcu Karakuzu; Ozarslan, Ali Can; Terzioglu, Pinar; Elalmis, Yeliz Basaran; Yucel, Sevil
    Involving a succession of oil refining stages for edible oil production, a notable constraint lies in the necessity to employ diverse adsorbents at various steps within these processes. This study investigates the synthesis of mesoporous silica aerogels from rice husk ash, comparing their efficacy in physical sunflower oil refining with earth clay (Bentonite) and commercial silica (Trisyl). Tetraethyl orthosilicate (TEOS) impact during aging was analyzed using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and N2 adsorption-desorption analyzer to examine alterations in the structure of silica aerogels. The surface areas of TEOS-doped silica aerogel (TSA) and non-TEOS-doped silica aerogel (NTSA) were 296.18 and 267.06 m(2)/g. Mesoporous silica aerogels were evaluated for their ability to reduce free fatty acids (FFA), peroxide value (PV), phosphorus, and color pigments in sunflower oil. TSA and NTSA demonstrated significant FFA removal, with TSA at 3 wt.% achieving the highest performance of 32.2%. TSA also effectively reduced PV and phosphorus compared to NTSA, Bentonite and Trisyl, exhibiting performance similar to Bentonite in the bleaching process. TEOS-doped silica aerogels have shown promise as adsorbents for impurity removal in sunflower oil and has emerged as the potential adsorbent that can comprehensively and effectively meet the requirements of many edible oil physical refining applications in a singular step. Mesoporous silica aerogel synthesis from rice husk ash with/without TEOS-doping. Mesoporous silica aerogels were compared to commercial adsorbents. For the first time mesoporous silica aerogels were used for oil adsorption with promising results. TEOS-doped silica aerogel was used to remove acids and peroxide in oil purification effectively. TEOS-doped silica aerogel performed effective color and phosphorus removal in oil purification.
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    Novel Adsorbents for Canola Oil Physical Refining: Mesoporous Calcium and Magnesium Silica Aerogel
    (Wiley-V C H Verlag Gmbh, 2025) Soylu, Tulay Merve; Karakuzu-Ikizler, Burcu; Terzioglu, Pinar; Yucel, Sevil
    The refining process of edible oil is essential for extending its shelf life by removing contaminants that negatively affect quality and consumer acceptance. This study evaluates the effectiveness of calcium silica aerogel, magnesium silica aerogel, a combination of both, bentonite, Trisyl, and various aerogel combinations in a single-stage physical refining process of crude canola oil. Calcium and magnesium silica aerogels were synthesized via the precipitation method from water glass and subsequently dried under ambient pressure using an air dryer. The synthesized aerogels were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, N2 adsorption-desorption analysis and bulk density measurements. The surface areas of the calcium and magnesium aerogels were found to be 45.67 m2/g and 616.46 m2/g, with densities of 0.15 g/cm3 and 0.18 g/cm3, respectively. The adsorption capacities of these adsorbents for free fatty acids, peroxides, and color pigments in crude canola oil were examined. The aerogels reduced free fatty acid levels by 14% to 47%, and their use in the refining process produced oil with a lighter color. Notably, the most effective peroxide removal, reaching 53.4%, was achieved with a 50:50 combination of aerogels. These findings demonstrate the potential of calcium and magnesium silica aerogels as effective adsorbents for removing impurities from edible oils.
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    Review on a novel biosilica source for production of advanced silica-based materials: Wheat husk
    (Wiley, 2019) Terzioğlu, Pınar; Yucel, Sevil; Kus, Cigdem
    The growing cognizance of environmental matters elucidates the increasing attention thought the evaluation of bio-based by-products and waste materials in various applications. The agricultural-based industry results in considerable amounts of residues containing silica. In the past decade, extensive research studies had been executed to evaluate agricultural waste materials such as rice husk and rice straw. The results of the studies point out the possibility of evaluating such wastes to produce silica-based materials. Wheat husk is such an abundantly available waste obtained from the wheat milling process. It is containing noncrystalline silica, and thus, it can also be evaluated to produce value added materials. This study presents a comprehensive overview of the researches carried out on the properties and utilization of wheat husk as a silica source. The summary and discussion presented in this review would provide knowledge on wheat husk that is convenient to be utilized for the low-cost and sustainable production of silica-based materials such as aerogel, metal silicates, zeolite, silica-based ceramics, and composites.
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    Role of magnesium and aluminum substitution on the structural properties and bioactivity of bioglasses synthesized from biogenic silica
    (Keai Publishing Ltd, 2020) Karakuzu-Ikizler, Burcu; Terzioğlu, Pınar; Basaran-Elalmis, Yeliz; Tekerek, Bilge Sema; Yucel, Sevil
    The objective of this study was to investigate the effect of magnesium (1 wt%) and aluminum (1 wt%) incorporation on the in vitro bioactivity and biodegradation behavior of 45S5 bioactive glasses synthesized from rice husk biogenic silica. The performance of biogenic silica-based samples was compared well with commercial silica-based counterparts. The in vitro biodegradation behavior of bioactive glasses was evaluated by the weight loss of samples and pH variation in the Tris buffer solution. Based on composition, bioglasses possessed different properties before and after simulated body fluid (SBF) immersion. The incorporation of magnesium (Mg) and aluminum (Al) enhanced the Vickers hardness of bioglasses. All the bioglasses showed the hydroxyapatite layer formation after SBF treatment as confirmed by the dissolution, FTIR, SEM and XRD analysis, however it was more prominent in the rice husk silica-based 45S5 bioglass. The biogenic silica seems to be a promising starting material for bioglass systems to be used in bone tissue engineering applications.
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    The effect of process variables on the properties of nanoporous silica aerogels: an approach to prepare silica aerogels from biosilica
    (Springer, 2017) Temel, Tulay Merve; Ikizler, Burcu Karakuzu; Terzioğlu, Pınar; Yucel, Sevil; Elalmis, Yeliz Basaran
    Silica aerogel, a nanoporous material, was produced by using rice husk ash via sol-gel method. The aim of the study is to examine effects of the acid type (acetic, hydrochloric, nitric, oxalic and sulfuric acid), dryer type (air, freeze, oven and vacuum) and the addition of tetraethyl orthosilicate on the structural and physical properties of aerogels produced from rice husk ash. In addition, this is the first study investigating the effect of vacuum oven drying on the structure of rice husk based silica aerogel. Specific surface area and pore size of obtained silica aerogels have been analyzed by the N-2 adsorption and desorption measurements at 77 K via Brunauer-Emmett-Teller (BET) and Barrett-Joiner-Halenda (BJH) methods, respectively. Surface functional groups were determined with fourier transform infrared spectroscopy (FTIR). Surface morphology was examined with scanning electron microscopy (SEM). Moreover, density was calculated by tapping method. The results showed that all of the variables had remarkable effects on the final properties of the silica aerogel. The BET specific surface area of the silica aerogels increased with the addition of tetraethyl orthosilicate, while the tapping density decreased. The BET specific surface area and pore size of silica aerogels varied between 140.7-322.5 m(2) g(-1), and 5.38-12.05 nm, respectively. Silica aerogel which was obtained by using oxalic acid, tetraethyl orthosilicate addition and air dryer had the highest BET specific surface area (322.5 m(2) g(-1)).