Mehmet Burçin Pişkin

A study on the structural behavior of reduced pyrite ash pellets by XRD and XRF analysis.

In Turkey, pyrite ash is created as waste from the roasting of pyrite ores in the production of sulfuric acid. These processes generate great amounts of pyrite ash waste that creates serious environmental pollution due to the release of acids and toxic substances. Pyrite ash waste can be used in the iron production industry as a raw material because of its high Fe2O3 concentration. The aim of this study was to investigate the reduction behaviour of pyrite ash pellets. The pyrite ashes were reduced to obtain the iron contained in pellets. Pyrite ashes samples were pelletized dried at 105 °C for 24 h and sintered at 1200 °C for 30 min. then reduced in a pressure of 4 atm. under argon gas. The mineralogical transformations that occurred during reduction were analysed by X-ray diffraction and X-ray fluorescence. The X-ray diffraction and X-ray fluorescence measurements of these samples showed that Fe3O 4 was successfully reduced to a metallic iron phase in a laboratory-scale electric arc furnace.

Effects of calcium hydroxide and calcium chloride addition to bentonite in iron ore pelletization

Pyrite ash is created as waste from the roasting of pyrite ores during the production of sulphuric acid. These processes generate great amounts of pyrite ash waste that is generally land filled. This creates serious environmental pollution due to the release of acids and toxic substances. Pyrite ash waste can be utilized in the iron production industry as a blast furnace feed to process this waste and prevent environmental pollution. The essential parameters affecting the pelletization process of pyrite ash were studied using bentonite as a binder. Experiments were then carried out using bentonite and a mixture of bentonite with calcium hydroxide and calcium chloride in order to make the bentonite more effective. The metallurgical properties of pyrite ash, bentonite, calcium hydroxide, calcium chloride, a mixture of these and sintered pellets were studied using X-ray analysis. The crushing strength tests were carried out to investigate the strength of pyrite ash waste pellets. The results of these analyses showed that pyrite ash can be agglomerated to pellets and used in the iron production industry as a blast furnace feed. The crushing strength of the pellets containing calcium hydroxide and calcium chloride in addition to bentonite was better than the strength of pellets prepared using only bentonite binder.

Thermal, spectral, and surface properties of LED light-polymerized bulk fill resin composites.

Abstract The aim of this study was to evaluate the thermal, spectral, and surface properties of four different bulk fill materials – SureFil SDR (SDR, Dentsplay DETREY), QuixFil (QF, Dentsplay DETREY), X-tra base (XB, Voco) X-tra fil (XF, Voco) – polymerized by light-emitting diode (LED). Resin matrix, filler type, size and amount, and photoinitiator types influence the degree of conversion. LED-cured bulk fill composites achieved sufficient polymerization. Scanning electron microscope (SEM) analysis revealed different patterns of surface roughness, depending on the composite material. Bulk fill materials showed surface characteristics similar to those of nanohybrid composites. Based on the thermal analysis results, glass transition (Tg) and initial degradation (Ti) temperatures changed depending on the bulk fill resin composites.

Nano Layers in the Bismuth Telluride Semiconductive Alloys that are Used in Nano Satellites

The level-to-level and island growth of nano-layers: copper, nickel and boron realizes spontaneously between the layers Te1-Te1 in the process of the directed crystallization of bismuth telluride (doped by easily diffusing impurities). This was proved by the electron-microscopic photos of the chipped surface (0001) Bi2Te3<B>, Bi2Te3<Cu> and Bi2Te3<Ni>. The wide set of island sizes 50-200 nm was revealed. The appearance nature of nano-layers, islands and their enlargement in the interlaminar space of the layered crystal of bismuth telluride is the same as on the open surfaces of the systems semiconductor-metal. The two-dimensional islands, which combining form the wetting layer of nano-thickness appear on the initial steps of the growth. It is established, that the copper layers, nano-sized by the height, are charged with extremal behavior of Hall thermoelectromotive force and other kinetic parameters Bi2Te3<Cu>. The temperature dependencies of coefficients of Hall, electroconductivity, mobility and other kinetic parameters revealed the oscillation character. These extremums can be connected with the consecution of the phase transfers, known as order-disorder transfers, connected with positional order. The anomal increase of the mobility of the charge carriers (more, than in 5 times) in the direction along axes of the (0001) Bi2Te3<Cu> layers at the temperature 105K is observed so it will be a great improvement that can be used in nano satellites.

The synthesis of silica-based aerogel from gold mine waste for thermal insulation

Energy consumption and increase in the greenhouse gases are very critical problem for all countries. In order to solve this problem, researches are focused on new thermal insulation materials that are the essential part of the energy-efficient buildings. Aerogels are called ‘the best thermal insulating materials’ due to their extremely low thermal conductivity. In this study, silica-based hydrophobic aerogel was synthesized by sol–gel method via ambient pressure drying. The silica source was obtained from the gold mine waste by alkali fusion method instead of using pure and expensive silica sources such as tetraethyl orthosilicate. The synthesized aerogels were used in the production of insulating plaster with different mass percentages (1, 5, 10, and 20%) and characterized by XRD, FT-IR, contact angle measurement, TG/DTA and N2 adsorption/desorption analysis. In addition, the thermal conductivity of the aerogel-based plaster was determined by using TCi thermal conductivity analysis. The results show that addition of aerogel to plaster was decreased the thermal conductivity and when the mass percentage was 20% the thermal conductivity decreases of 63% as compared to the natural plaster without aerogel.

Determination of lemon and carbonate effects on caffeine content of various teas and investigation of daily caffeine intakes / Çeşitli çayların içerdikleri kafein miktarlarına limon ve karbonatın etkisi ve günlük alım miktarlarının incelenmesi

Abstract Objective: Tea (Camellia sinensis), has been used for health field in thousands of years. Caffeine is one of the key component in tea and investigation of caffeine is a popular working subject among the researches. The novelty of this study is not only the determination of the caffeine contents of the teas, but also how addition of lemon and carbonate effects the caffeine contents. Another aim of the study is the investigation of the daily caffeine intakes from teas. Methods: Tea infusions were prepared and caffeine contents were extracted by using chloroform and determined by UV-Vis Spectrophotometer. For lemon and carbonate addition experiments, lemon was added before the caffeine analysis and carbonate was added at the beginning. Results: Maximum caffeine contents from highest to lowest were seen in black, earl grey and green in classic teas; fennel, mint and sage in herbal teas; lemon, apple and rosehip in fruit teas. With lemon addition caffeine contents were increased except green tea and with carbonate addition caffeine contents were decreased except black and fennel tea. Daily caffeine intakes are found between 32.10% (green tea with carbonate) - 77.20% (black tea with lemon), 1.85% (sage tea with carbonate) - 4.05% (fennel tea with lemon) and 2.10% (rosehip with carbonate) - 4.00% (lemon tea with lemon) in classic, herbal and fruit teas, respectively. Conclusion: The significance of this study indicates that herbal and fruit teas contain caffeine, which is assumed zero in literature. The caffeine amount of herbal teas (20.79±0.36-30.68±0.63 ppm) were found barely higher than the fruit teas (22.87±0.54-28.54±0.75 ppm) but daily maximum caffeine intakes were found less than 5%. The daily maximum caffeine intakes were found in the teas as 525.36±2.84-20.79±0.36 ppm, where lemon addition increased to 617.90±3.54-22.97±0.58 ppm and carbonate addition decreased to 488.54±2.05-16.84±0.28 ppm. Özet Amac: Çay (Camellia sinensis) binlerce yıldır sağlık alanında kullanılmaktadır. Kafein, cayın içerisindeki önemli bileşenlerden biri olup araştırmacılar arasında popüler bir calışma konusudur. Bu çalışmanın yenilikçi yönü sadece cayların icerdikleri kafein miktarlarının belirlenmesi değil aynı zamanda kafein içeriğine limon ve karbonatın nasıl etki ettiğinin incelenmesidir. Ayrıca bu çalışmanın diğer bir amacı da çaylardan alınan günlük kafein alım miktarlarının hesaplanmasıdır. Metod: Çaylar demlenip kafein miktarları kloroformla ekstrakte edilmiş ve UV/Vis spektrofotometresiyle belirlenmiştir. Limon ve karbonat eklemeli deneylerde limon, kafein analizinden önce, karbonat ise başlangıçta eklenmiştir. Bulgular: Maksimum kafein içeriği çoktan aza doğru klasik çaylardan siyah, bergamut ve yeşil çayda; bitki çaylarından rezene, nane ve ada çayında; meyve çaylarından limon, elma ve kuşburnu çayında belirlenmiştir. Limon eklenmesi yeşil çay hariç kafein miktarını arttırmış. Günlük kafein alımları %32.10 (karbonatlı yeşil çay) - %77.20 (limonlu siyah çay), %1.85 (karbonatlı ada çayı) - %4.05 (limonlu rezene çayı) ve %2.10 (karbonatlı kuşburnu çayı) - %4.00 (limonlu limon çayı) olarak sırasıyla, klasik, bitki ve meyve çaylarında bulunmuştur. Sonuç: Bu çalışmada, literatürde sıfır olarak kabul edilen kafein içeriğinin bitki ve meyve çaylarında bulunduğu gösterilmektedir. Bitki çaylarının kafein miktarları (20.79 ±0.36-30.68 ±0.63 ppm), meyve caylarına (22.87 ±0.54-28.54 ±0.75 ppm) kıyasla daha düşük olarak bulunmuş ama günlük maksimum alımlarının %5’ten duşuk olduğu belirlenmiştir. Günlük maksimum kafein alımları klasik çaylarda ve meyve çaylarında bulunmuş (525.36 ±2.84-20.79 ±0.36 ppm) olup limon eklenmesi tum cayların kafein miktarını yukseltirken (617.90 ±3.54- 22.97 ±0.58 ppm), karbonat eklenmesi tum çaylarda kafein miktarını azaltmıştır (488.54 ±2.05-16.84 ±0.28 ppm).

The use of boric acid (H3BO3) and boron oxide (B2O3) for co-precipitation synthesis of cobalt-boron catalysts: Catalytic activity in hydrogen generation

The use of boric acid (H3BO3) and boron oxide (B2O3) for the synthesis of cobalt-based catalysts by the co-precipitation technique was investigated and catalytic activities in hydrogen generation were evaluated. Different cobalt salts [cobalt (II) chloride (CoCl2 · 6H2O), cobalt sulfate (CoSO4 · 5H2O) and cobalt(II) nitrate (Co(NO3)2 · 7H2O)] were used with H3BO3 and B2O3 to prepare Co based catalysts. Crystalline, surface and chemical characteristics were clarified using X-ray diffraction (XRD); low temperature adsorption of nitrogen (BET), scanning electron microscopy (SEM), and inductively coupled plasma optical emission spectroscopy (ICP-OES). Three types of powder samples were obtained according to the different boron sources and cobalt salts, and it was found that an efficient Co based catalyst was obtained by co-precipitation of B2O3 and CoCl2 · 6H2O salt. Additionally, the effect of temperature, stabilizer ratio and NaBH4/catalyst ratio on parameters, characterizing the reaction of hydrogen generation was investigated. The zero order, first order and Langmuir-Hinshelwood kinetic models were used to identify the effect of Co based catalysts on the behavior of the catalytic system in hydrogen generation. Kinetic parameters of hydrogen generation for zero-order kinetic model were calculated for the following conditions: the rate of hydrogen generation is 0.93 L H2 g−1 catalyst min−1, the activation energy is 43.55 kJ mol−1 and the constant of Arrhenius equation is 11 min−1.

The Preparation of Silicon and Aluminum Alkali Extracts from Fused Turkish Coal Fly Ashes

Abstract Large quantities of solid waste generated from households, offices, shops, markets, restaurants, public institutions, industrial installations, water works and sewage facilities, construction and demolition sites, and agricultural activities. It causes environmental problems such as groundwater contamination, atmospheric and water pollution, etc. when it is disposed in landfills. Fly ash is the by-product of the coal combustion process for energy generation and remains a major problem in many parts of the world. The large amounts of fly ash are produced and the annual production of it has continued to increase. The disposal of fly ash may cause long-term adverse environmental effects. In this study, the silicon and aluminum in two different Turkish fly ashes (Afsin-Elbistan and Catalagzi) were activated by fusion with sodium hydroxide. The obtained leachates were analyzed for silicon and aluminum content by inductively coupled plasma optical emission spectrometry (ICP-OES). In addition, the mineralogical and chemical properties of these fly ashes are compared.

About some mechanisms of consolidation of layered highly effective crystals For thermoelements

The physical and mechanical properties of monocrystals Bi2Te3, alloyed by two kinds of impurity are investigated: being easy diffusionable and hard diffusionable. Easy diffusibility of the additive (nickel, iron, silver, copper) at the certain parities (ratio) inside quintet and in among slide space can consolidate or “to loosen” layers.