Person: ÇETİNER, BURCU NİLGÜN
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ÇETİNER
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BURCU NİLGÜN
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Publication Metadata only Investigation of Alkaline Leaching Parameters on Stibnite Concentrate(SPRINGER HEIDELBERG, 2020) ÇETİNER, BURCU NİLGÜN; Aktas, Serdar; Cetiner, Burcu NilgunAccording to critical statistical studies, antimony is one of the rarest elements in the world, and global resources could be exhausted by 2050. In light of these observations, its extraction will be costly due to poor-quality ore, deep mining, remote locations, and high energy consumption. In the present study, an alkaline leaching process was carried out on stibnite concentrate to evaluate the effect of reaction parameters on the percentage of antimony extraction. The leaching efficiencies of different sulfur and hydroxide sources were studied and compared to one another to create a better understanding of the reaction process. Kinetic models were investigated to identify the reaction pathway and calculate the activation energy. The activation energy of the stibnite dissolution was assessed as 19.13 kJ/mol using a two-dimensional diffusion-reaction model. The value of activation energy indicates the quantity of energy necessary for a reaction to proceed. As expected, potassium hydroxide leaching was significantly more successful than was sodium hydroxide; however, in terms of economics, the use of sodium hydroxide was found to be more cost-efficient. Interestingly, this finding indicated that caustic leaching is still the most effective method for stibnite extraction.Publication Open Access Comparison of the Antimony Cementation from Chloride Media Using Various Cementators(2022-04-01) ÇETİNER, BURCU NİLGÜN; AKTAŞ, SERDAR; Kucukoglu O., ÇETİNER B. N., Morcali M. H., AKTAŞ S.This study compares the cementation performance of metallic iron, metallic aluminum, and metallic tin in terms of the reaction conditions and parameters in synthetic antimony chloride solutions. The effects on the antimony recovery (%) caused by the cementators\" types, stirring speed, reaction time, and temperatures were explored thoroughly. The cementation kinetics of antimony were also explored for each cementator. The activation energies were determined to be 10.99, 9.09, and 13.58 kJ mol(-1) for Al, Fe, and Sn, respectively. The results reveal that the reaction is diffusion controlled, and comparable results were obtained for each cementator. At 25 degrees C, 40 mg of iron powder was found to reduce all antimony ions (i.e., approx. 99% recovery), but even when 100 mg of Al and Sn cementators were used, the antimony recovery did not reach 100%. This result shows that iron is the best candidate to cement antimony out of the solution.Publication Metadata only Production and Characterization of Alumina-Titania Biocomposite(AMER INST PHYSICS, 2015) ÇETİNER, BURCU NİLGÜN; Cetiner, B. N.; Erkmen, Z. E.; Oral, AY; Bahsi, ZB; Ozer, M; Sezer, M; Akoz, MEAlumina is a biomaterial of choice for more than 20 years due to its high hardness accompanied by low friction, wear and inertness to in vivo environment. It has been reported that titanium oxidized to the rutile phase is bioactive. This is a property discovered for certain ceramics such as Bioglass and sintered hydroxylapatite (HA). But the combination of alumina and titania forming tialite (Aluminium titanate-50 mol % Al2O3 and 50 mol % TiO2) is a new challenge. In this work we made firstly the beneficiation of the Seydisehir alumina by leaching it in the acidic solution the Aqua Regia followed by preparation of batches containing 2,5 wt %, 3,5 wt % and 4,5 wt % of MgO as the sintering aid, 1 wt % of SiO2 and the balance; the alumina and titania powder mixture (1:1 mole). After sintering these batches at 1600 degrees C for about 12 h, their mechanical properties (the compression and hardness testings) and phase ratios (the XRD analysis) were analyzed and compared with the control group containing the laboratory scale alumina instead of the Seydisehir alumina. Following the characterization (the SEM and the EDS analysis) of the substrate material, the comparison of two different materials was carried out.Publication Open Access The similar and dissimilar spot welding of 304 and 316l austenitic stainless steels(2017-11-01) ÇINAR, ÖZGÜR; ÇETİNER, BURCU NİLGÜN; GÜLLÜOĞLU, ARİF NİHAT; EKİCİ, BÜLENT; ÇINAR Ö., ÇETİNER B. N., TOPCU İ., GÜLLÜOĞLU A. N., EKİCİ B.Publication Open Access Metallic antimony recovery via cementation from antimony containing solutions and investigation of its conditions(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2021-05-20) ÇETİNER, BURCU NİLGÜN; Uysal, Abdullah; Cetiner, Burcu Nilgun; Aktas, SerdarBesides the most common uses of antimony metal and / or compounds, with the development of solar energy technologies, the need for antimony and its compounds increases and the rapid depletion of primary sources in the world increases the importance of antimony recovery from secondary sources. The recovery method proposed in this study aims to reduce the ionic antimony by oxidation of the more active metal and to produce metallic antimony in powder form as a result of reduction process. Oxide based antimony containing ore has been treated by acidic solutions. But as the recovery rate was too low, the parameters affecting the metallic precipitation of antimony from acidic synthetic antimony solutions which are a secondary source were examined in detail. The physical and chemical properties of antimony metal were determined after examining reaction time, temperature, initial antimony concentration, zinc powder amount and solution pH parameters during cementation process which could affect experimental working conditions. As a result of the experimental studies, using 25 mL of 1000 ppm Sb3(+) synthetic solution with the addition of 100 mg of metallic zinc and mixing speed of 60 rpm, recovery efficiency of up to 100% was achieved in a noticeably short time such as 5 minutes and metallic antimony of 99% purity was obtained. When 100% recovery was achieved with zinc of 100 mg in single-stage cementation, the same yield was achieved with the addition of 40% less zinc in two-stage cementation.Publication Open Access INVESTIGATION OF INDENTATION FRACTURE TOUGHNESS (K-IC) AND WEIBULL PARAMETERS OF 0.25Li(2)O.2SiO(2)-0.75BaO.2SiO(2) GLASS-CERAMIC(POLSKA AKAD NAUK, POLISH ACAD SCIENCES, INST METALL & MATER SCI PAS, 2017-12-01) ÇETİNER, BURCU NİLGÜN; Ertug, B.; Cetiner, B. Nilgun; Gokce, H.; Erkmen, Z. Engin; Ovecoglu, M. LutfiIn the present study, mechanical properties of 0.25Li(2)O.2SiO(2)-0.75BaO.2SiO(2) glass-ceramic were investigated. The transformations temperatures were determined by DTA instrument. The optimum nucleation temperature was found to be 540 degrees C. This suggested the crystallization temperatures as 675, 720 and 800 degrees C. After carrying out crystallization heat treatments, Vickers indentation test was applied. In order to determine the indentation fracture toughness (KIC), crack half-length, 'c' of the samples was measured. To calculate KIC, Young's modulus, E and the measured hardness, Hv were used. Using KIC and probability of fracture, 'P', ln ln[1/(1-P)]-ln KIC graph was drawn based on the Weibull distribution equation. Consequently, Weibull modulus,, m` and scale parameter, 'K-0' were determined and compared with each other.Publication Open Access Palladium recovery from spent Pd plating solutions using Lewatit TP 214 resin(2022-03-01) ÇETİNER, BURCU NİLGÜN; AKTAŞ, SERDAR; ÇETİNER B. N., Yegul E. U., Zeytuncu Gökoğlu B., AKTAŞ S.This study aims to explore the recovery of palladium (Pd(II)) ions using Lewatit TP 214 resins. Waste Pd(II) ions with ammonia complex procured from a precious metal plating were selected as the source solution. In the experimental studies, two stock solutions of 60 ppm Pd(II) with a pH value of 4.0 and 7.5 were prepared as initial solutions. The experiments were performed by altering four parameters: solution pH, time 15-180 min, temperature 25 degrees C-60 degrees C, and amount of resin 100-400 mg. It was proved that the recovery percentage increased with higher temperature and resin at lower pH values. The Pd(II) recovery percentage increased with a temperature rise, reaching 100% after 40 min at pH 4.0 and 60 degrees C. On the other hand, a bit lower efficiency (95%) was attained after 180 min at pH 7.5 and 60 degrees C. Using Lewatit TP 214, the computed activation energies for Pd(II) recovery are 17.73 and 15.62 kJ/mol at pH 4.0 and 7.5, respectively. Considering these activation energy values, a mixed mechanism dominated the recovery of Pd(II).